guidelines for reducing flood losses · symposium on flood forecasting for the americas, held in...

Guidelines for Reducing Flood Losses

I S D RInternational Strategy

for Disaster Reduction

A contribution to the International Strategy for Disaster Reduction (ISDR)

United Nations

UN Department of Economic and Social Affairs (DESA)Division for Sustainable Developmentwww.un.org/esa/sustdev

UN Inter-Agency Secretariat of the International Strategy for Disaster Reduction (UN/ISDR)www.unisdr.org

National Oceanic and Atmosphere Administration (USA NOAA)www.noaa.gov


United Nations

Acknowledgements

Paul J. Pilon, Editor and Contributor

UN Department of Economic and Social Affairs (DESA)Manuel Dengo, Water, Natural Resources and Small Islands Branch,Division for Sustainable DevelopmentMarcia Brewster, Water, Natural Resources and Small Islands Branch,Division for Sustainable DevelopmentHenrike Peichert, Water, Natural Resources and Small Islands Branch,Division for Sustainable DevelopmentAslam Chaudhry, Water, Natural Resources and Small Islands Branch,Division for Sustainable DevelopmentMika Sainio, Division for Sustainable Development

Inter-Agency Secretariat of the International Strategy for Disaster Reduction (UN/ISDR)John Harding, Scientific & Technical CoordinationNicole Rencoret, Production CoordinationMario Barrantes, Graphic DesignStéphane Kluser, Graphic Design

UN Economic and Social Commission for Asia and the Pacific (UNESCAP)David Jezeph, Water and Mineral Resources Section, Environment and Natural Resources Development Division

United States of America, National Oceanic and Atmospheric Administration(USA NOAA)Curt Barrett

World Meteorological Organization (WMO)Wolfgang Grabs, Water Resources Division

ContributorsDennis A. DavisRobert A. HallidayRichard Paulson

Case StudiesUnited Nations Development Programme, Vietnam, Disaster Management UnitRANETZenaida Delica, Asian Disaster Preparedness Center

Cover photo: 1998 flood in Dhaka, Bangladesh. A. Rahim Pev.

i

Also available on-line at www.unisdr.org

A contribution to the International Strategy for Disaster Reduction

This publication was made possible thanks to the support of the United States of America, National Oceanic andAtmospheric Administration, (USA NOAA) and the Swiss Agency for Development and Cooperation (SDC).

ii


Foreword

Throughout the history of mankind, floods have brought untold wealth and prosperity tocivilizations, and yet at the same time, they have caused tremendous losses and resulted inuntold suffering for millions of people. Even today, floods lead all natural disasters in thenumber of people affected and in resultant economic losses, with these numbers rising atalarming rates.

In response to the devastation arising from water-related natural disaster, particularlyflooding, a series of three workshops and symposia were held, sponsored by the UnitedStates National Oceanic and Atmospheric Administration (NOAA) and the United NationsDepartment of Economic and Social Affairs. One objective of these events was to createcomprehensive guidelines that could be used by governments, international organizations,non-governmental organizations and civil society to help avert losses from flooding.

The first session was the Flood Forecasting and Disaster Response Workshop. It was held inTegucigalpa, Honduras, from 6-8 April 1999, following the devastation in the regionstemming from Hurricane Mitch. This workshop was followed by an internationalSymposium on Flood Forecasting for the Americas, held in Brasilia, from 15-19 November1999, and it was hosted by the National Institute of Meteorology of Brazil. A rough draft ofthese guidelines was prepared following this meeting. From 27-31 August 2001, anInternational Symposium on Water-related Disaster Reduction and Response was held inBangkok, Thailand, wherein the draft guidelines were reviewed and new materials weregathered. Materials and ideas from these three meetings have been incorporated into thispublication. It is hoped that these guidelines can be further improved and that additionalexperiences and concepts can be shared globally in an updated version.

This publication is based on the findings of those three sessions and is a contribution to theoverall efforts that are required to help society cope with the forces of nature. Focused effortsare required to reduce the risk of flooding on society. Flood forecasting and warningsystems, data collection systems, flood plain management practices and land-use planning, aswell as economic and social measures can be adopted within an integrated framework to leadto sustainable solutions. Concerted efforts are required to achieve these solutions, and suchefforts are necessary to stem the rising losses from water-related disasters. It is truly hopedthat these guidelines will assist in the planning and implementation of actions leading tomore healthy and resilient societies.

José Antonio OcampoUnder-Secretary-GeneralUnited Nations Department of Economic and Social Affairs

General David Johnson Assistant AdministratorWeather Services USA NOAA National Weather Service

iv


Executive Summary

Floods have the greatest damage potential ofall natural disasters worldwide and affect thegreatest number of people. On a globalbasis, there is evidence that the number ofpeople affected and economic damagesresulting from flooding are on the rise at analarming rate. Society must move from thecurrent paradigm of post-disaster response.Plans and efforts must be undertaken tobreak the current event-disaster cycle. Morethan ever, there is the need for decisionmakers to adopt holistic approaches forflood disaster management.

Extreme flooding events are not relegated tothe least developed nations, but can alsodevastate and ravage the most economicallyadvanced and industrialized nations. In thelast decade there has been catastrophicflooding in Bangladesh, China, India,Germany, Mozambique, Poland, the UnitedStates and elsewhere. When floods occur inless developed nations, they can effectivelywipe out decades of investments ininfrastructure, seriously cripple economicprosperity, and result in thousands of deathsand epidemics. The majority of the deathsassociated with such disasters can be foundwithin the most vulnerable members ofsociety, namely women and children. Thegreatest tragedy is that most of these deaths,associated post traumatic stresses, and socialand economic hardships can be eitheravoided or dramatically reduced throughpre-, during, and post-disaster investmentsin preparedness activities and associatedinfrastructure, flood plain policydevelopment, effective watershed land useplanning, flood forecasting and warningsystems, and response mechanisms.

It is recognized that comprehensiveassessments of risks from natural hazards suchas flooding, mud/land slides, and extremewind and rain are necessary for society tobetter understand the risks which they facedaily. Assessment of risk and the involvementof the community in the decision making,planning and implementation process can helplead to sustainable solutions. Solutions mustreflect the human dimension and must alsoconsider the impacts of changing land use onflooding, erosion, and landslides. Integratedwater management practices must beembraced. Societies have much to learn fromnew approaches such as better forecastingtechniques and applying experience gainedfrom flood events and mitigation effortsemployed elsewhere. Implementation will onlybe sustainable if solutions are suitable for thecommunity at risk over the long term. Asstorms will continue to occur, risk assessmentand planning followed by actions are neededto help reduce the overall risk to society, theeconomy and the environment.

These guidelines are oriented to the needs ofthe decision-maker and provide a descriptionof the range of mitigation options that need tobe considered when making efforts to reducelosses from flooding. The guidelines aredesigned to provide an introduction to thegeneral area and to introduce the reader tovarious measures to mitigate the impactsassociated with floods. A bibliography isprovided that cites detailed material availablefor the planning and implementation stages.These guidelines are not meant to addressfloods resulting from storm surge, ice ordebris jams, or the failure of human-madestructures.


1

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1. Socio-Economic Aspects of Water-Related Disaster Response . . . . . . . 131.1 Social Aspects of Disaster Reduction and Response . . . . . . . . . . . . . . . . . . . . . . . . . . 141.2 Economic Aspects of Disaster Reduction and Response . . . . . . . . . . . . . . . . . . . . . . 161.3 Response Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181.4 Public Awareness and Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2. Key Elements of Flood Disaster Management . . . . . . . . . . . . . . . . . . . . . . 232.1 Risk Management and Flood Plain Delineation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242.2 Supportive Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.3 Flood Plain Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312.4 Watershed Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372.5 Climate Variability and Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382.6 Development of Policies, Strategies and Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392.7 Emergency Preparedness and Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3. Integrated Flood Forecasting, Warning and Response System . . . . . . . 473.1 Defining an Integrated System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483.2 The Hydrometeorological Network for Forecasting . . . . . . . . . . . . . . . . . . . . . . . . . 543.3 Meteorological Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563.4 The Forecast Centre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4. Establishing an Integrated System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Annex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Case Study 1: Community Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Case Study 2: Regional Cooperation in Southern Africa . . . . . . . . . . . . . . . . . . . . . . . . . . 73Case Study 3: An Instructional Programme for the Local Level . . . . . . . . . . . . . . . . . . . 75Case Study 4: Access to Information - The RANET Project . . . . . . . . . . . . . . . . . . . . . . 77

Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

3

Introduction

4

There is an increasing trend worldwide inthe number of disasters and their totaleconomic impacts. This is very evident inthe analysis by Munich Re, a majorreinsurance company, of what it terms GreatNatural Catastrophes1 (see Figures 1 and 2).Flooding causes over one-third of the totalestimated costs and is responsible for two-thirds of people affected by natural disasters.Over 90% of people affected by naturaldisasters worldwide live in Asia, as thecountries in Asia with large populations areparticularly prone to recurrent flooding.

The number of disasters attributed toflooding is on the rise (see Figure 3), whilethe number of people killed2 due to floodingremains steady (see Figure 4). However, theoverall number of deaths due to all naturaldisasters is decreasing, and this has beenattributed to investing in early warning andpreparedness programmes. There is analarming increasing trend in the number ofpeople affected by natural disasters with anaverage of 147 million affected per year(1981-1990) rising to 211 million per year(1991-2000), with flooding alone accountingfor over two-thirds of those affected. Thismight well be a result of the increasinggrowth of urban populations, some portionsof which may be in flood-prone areas.

Figure 5 shows the number of people thathave been affected by natural disasters from1975 to 2000 by income and disaster type.More than 95% of all deaths as a result ofnatural disasters are in the least developednations, and these same nations have thegreatest number of people affected bynatural disasters. Typically, disasters impactthe elderly, women and children the most.

1 Munich Re in their 2001 annual review of natural catastrophes defines these as follows: "Natural catastrophes are classed as great if the ability of the region tohelp itself is distinctly overtaxed, making interregional or international assistance necessary. This is usually the case when thousands of people are killed,hundreds of thousands are made homeless or when a country suffers substantial economic losses, depending on the economic circumstances generallyprevailing in that country."

2It should be noted that deaths from storm surge caused by cyclones are not included in these figures on floods, but are classified as resulting from wind storms.For example, in Bangladesh over 300,000 people were killed in tropical cyclones in 1970 and over 138,000 people in 1991.

This is a trend that will continue unlessconcerted actions are taken to mitigate theimpacts from natural hazards.

Flooding is the single most destructive typeof natural disaster that strikes humans andtheir livelihoods around the world. In thelast decade, there has been catastrophicflooding experienced in China, India,Bangladesh, Germany, Poland,Mozambique, the USA, and elsewhere.Flooding is not restricted to the leastdeveloped nations, but also occurs indevastating fashion in the most developedand industrialized countries of the world.However, it is the citizens of the leastdeveloped nations that suffer the highest tollfrom the occurrence of flooding. If we lookat Hurricane Mitch as one specific example,it caused massive destruction and loss of lifein Central America, affecting the peoples ofHonduras, Nicaragua, El Salvador, andGuatemala. Honduras was hardest hit witheconomic losses estimated as beingapproximately US$ 3.64 billion(UNDP/ECLAC, 1998) or about 69% oftheir annual gross domestic product (GDP)in 1998 (IMF, 2002). In comparison,Hurricane Andrew resulted in estimateddamages of US$ 30 billion (seehttp://www.aoml.noaa.gov/hrd/Landsea/Usdmg). These damages represented less than0.5% of the GDP of the USA (IMF, 2002).When natural disasters such as floodingoccur in developing nations, they caneffectively wipe out decades of investmentsin infrastructure and the personal wealth ofmany of its people, not to mention thecountless loss of lives, physical injuries,sickness and psychological trauma thatresult from the disasters.

5


Figure 1

World economic losses from 1950-2002 for great natural catastrophes*

Source: Munich Re, 2002*Note: Far exeeding 100 deaths and/or $US 100 million in claims

Economic losses (in billion $US, 2001 values)of which insured losses (in billion $US, 2001 values)

Trend of economic lossesTrend of insured losses

>167

0

10

20

30

40

50

60

70

80

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Billion $US

Figure 2

Number of great natural catastrophes from 1950-2001

Source: Munich Re, 2002

OthersFlood

WindstormsEarthquakes

0

2

4

6

8

10

12

14

16

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

6

Figure 3

Number of disasters attributed to floods, 1975-2001

Source: EM-DAT, CRED, University of Louvain, Belgium

Number of disasters

1975

1980

1985

1990

1995

2000

0

20

40

60

80

100

120

140

160

Figure 4

Number of people killed in floods, 1975-2001

Source: EM-DAT, CRED, University of Louvain, Belgium

0

5 000

10 000

15 000

20 000

25 000

30 000

35 000

2000

1995

1990

1985

1980

1975

Number of people killed

7


In recent years, water topics have receivedgreat attention on the international agenda.The challenge for disaster and watermanagers is to bring their communitiestogether and have them raise their combinedprofile at world and national policy events soas to allow for a greater ability to influencepractices. The implementation of integratedwater resources management (IWRM) hasnot been fully achieved in either developingor developed countries; and water continuesto be managed in a compartmentalizedfashion. The challenge is to recognize theimportance of the impacts of natural water-related hazards within the framework ofsustainable development.

Communities, nations, and regions can nolonger afford to simply respond to andrecover from these disasters. An integratedapproach to flood disaster management willreduce the losses and break the cycle ofevent-disaster. A paradigm shift is requiredin perceptions, attitudes and practices in

order to move from the current model ofpost disaster response and recovery to one ofinvesting in the holistic disaster managementprocess. The long tried approach ofproviding aid after a disaster needs to bealtered to increasing investments in disastermitigation management approaches beforethe occurrence of the next extreme event.

Flood disaster management is an end-to-endprocess for recognizing and effectivelycombating the risk associated with floodsthrough a suite of planned actions. Theprocess involves a number of activities thatoccur throughout the cycle:

• Pre-disaster - preventative measures andpreparedness;

• During the flood - disaster relief,response and mitigative actions; and

• Post disaster - rehabilitation,reconstruction, economic recovery, andefforts to assess and fine-tunepreventative measures.

Figure 5World overview from 1975-2000 of number of people affected categorized by income class and disaster type

Source: ADRC, EM-DAT, CRED, University of Louvain, Belgium

DroughtEarthquake Volcano

Flood

Slide

Wind strormEpidemicOthers

0 500 1 000 1 500 2 000 2 500

2 237 777 288 (55.58%)

50 581 617 (1.26%)

82 328 879 (2.04%)

1 655 512 440 (41.12%)

High Income

Upper MiddleIncome

Lower MiddleIncome

Low Income

Million people

8

Hurricane Mitch Devastation

Hurricane Mitch, a category five hurricane, devastated Central America in 1998,causing widespread flood, storm surge, landslide and mudslide damages. HurricaneMitch had wind speeds in excess of 240 kilometres per hour (150 miles per hour), andrainfall over a four-day period that exceeded 1,500 mm (59 inches) for several areasnear the Pacific coast. Over 3.5 million people were affected, an estimated 9,214 werekilled and 12,845 were injured. Damages have been reported to have exceeded $US 4.5billion (UNDP/ECLAC, 1998) to $US 7 billion3, primarily in Honduras, Costa Ricaand Nicaragua. In Honduras the damages represented over 69% of GDP and about73% of the total external debt. Major infrastructure such as bridges and roads wereseverely damaged and will take many years to be replaced.

On 3 November, residents of Tegucigalapa,Honduras look at homes destroyed by amudslide on Cerro El Berrinche. Triggered bytorrential rains from the tropical depressionthat had been Hurricane Mitch, floods andearth slides devastated the region. Honduranofficials put the death toll at 5,000 people, andclimbing, with half a million left homeless.

3Source: Der Weltamanach,http://www.weltalmanach.de/archiv/00_338.html

Effective planning measures require anunderstanding of the factors that contributeto losses due to flooding. Typically, multipleactions must be taken to proactively managethe risk. A multiple mitigation approachwould consider measures such as:preventing or restricting new orinappropriate development or activities inthe flood plain; removal of certain structuresfrom the floodway; flood proofing ofstructures in the flood plain; introduction ofstructural measures such as levees, damsand constructed channels; controlling landuse practices within the basin; and applyingflood forecasting and warning systems

linked with response mechanisms. There isseldom a single approach to reduce andmanage risk, but rather an array of measuresthat run from the development andenforcement of policies to the constructionof works to the development of the forecasts,warnings, and response programme.Emphasis should be placed on arriving atsolutions that are practical, appropriate andsustainable for the community at risk.

Establishing a flood forecastingprogramme enhances all other floodmitigation measures. Forecasts provide thenecessary lead-time for a wide variety of

Pho

to: J

. Val

dés

9

Guidelines for Reducing Flood Lossesactions to be taken by the community.Actions can reduce loss of life andeconomic losses by evacuating families,personal effects, produce, livestock andmachinery, and by taking short-term effortsto increase the capacity of structuralmeasures such as sandbagging operationsand flood control operations at dams. Evenin what are considered areas with lowpossibilities of flooding, complacency canset in and investments in forecasting andother mitigation efforts may be curtailed.Long-term investments and policies areneeded so that the community will beprepared to respond to the relatively rareevent when, not if, it happens.

Social and economic aspects are also veryimportant and must be considered toeffectively mitigate the impacts resultingfrom floods. Disasters in developingcountries can literally wipe out theinvestments made in infrastructure of theprevious 50 years, emphasizing theimportance of sustainable practices in thedesign of the fabric of society and itseconomy. There is a need to build resilienceto floods within the society. This is, in part,achieved through the recognition that thelevel of risk to society is highly linked toindifference and poverty, with thisassociation being mutually reinforcing.Factors such as low income, inadequatehousing, issues of land tenure, and lack ofpublic services and social security force thepoor to take actions that expose them togreater on-going risk. There is a need forgovernments to include the impacts ofdisasters in their financial planning scenariosand economic growth rate projections. Thiswould trigger an awareness that inadequatemeasures lead to enormous economic andsocial shocks associated with disasters.Possibly through effective long-term fiscalplanning, governments would betterrecognize the linkages between investmentsin flood disaster management and long-termsocial and economic stability.

There are many types of water-relateddisasters besides floods. Heavy rains canalso produce mudslides, landslides, andreleases of pollution. On the other extreme,there is also the possibility of drought. Thenegative impacts of drought in somecountries can equal or even exceed the socio-economic damages of floods. Drought alsoreinforces the persistence of poverty,especially in rural areas that have a lowadaptive capacity by the local population andweak institutions managing flood anddrought-related disasters. The principles ofintegrated water resources management arebeing advocated to lead to sustainablepractices for the benefit of society and theenvironment. There is a need for multi-hazard management systems within theframework of integrated water resourcesmanagement. This report addresses only theflood aspects. From this holistic perspective,there is also a need to develop a similarapproach for drought - the silent killer ofthe rural poor. The treatment of drought isdifferent from flood, due to its slow onsetand the absence of precise or standardizeddefinitions.

This document is intended for the politicaldecision maker, such as a mayor or minister,who wants to take positive steps to reduceflood losses but does not know how toproceed. The information outlined in thisreport provides guidance on a variety ofmeasures. Some of these include identifyingand mapping of areas prone to land/mudslide and flooding, preventing developmentin such hazard prone areas, enforcingcontrols on land use, and in implementingflood forecasting and warnings andemergency response programmes. Theseactions can significantly reduce the loss oflife, socio-economic damages anddisruptions to the communities. Additionalbenefits are also realizable in that a floodforecasting and warning programme canalso provide much needed information onwater availability for integrated water

10

management leading to reduced waterconflict and optimal water usage. Thisreport stresses that one of the biggestchallenges facing the decision-maker is todevelop the appropriate linkages between theagencies involved at all levels andovercoming the rigidity of operationalmandates.

The report is divided into seven majorsections. The first section is the introductionto the report, while the second introducessocial and economic aspects within flooddisaster management, and highlightsresponse strategies at various governmentallevels. This section also addresses aspects ofpublic awareness and communicationswithin flood disaster management. The thirdmajor section provides an overview ofvarious mitigation measures and technicalaspects pertaining to flood management.These concepts span a brief introduction torisk management concepts, flood plaindelineation, and watershed management

practices. The need for development ofpolicies, plans, and programmes is alsoaddressed, as are climate variability andchange and how these might impact uponflood hazards. The fourth major sectionprovides an in-depth description of thecomponents for consideration within a floodforecasting, warning and response system.This section provides the reader with anoverview of what constitutes an integratedsystem, its individual components, and howthese should be brought together to providetimely and reliable forecasts and warningsduring critical periods. The fifth majorsection provides an overview of how todevelop an integrated flood forecast,warning and response system. Abibliography is provided to facilitate theinterested reader in obtaining a host ofrelated material for more detailed study. TheAnnex contains four case studies outliningpragmatic examples of implementingconcepts that are advocated within thisdocument.

11


Integrated Water Resources Management

Integrated water resources management (IWRM) is an alternative to the dominant sector-by-sector, top-down management style of the past. IWRM aims at: integratingmanagement of water resources at the basin or watershed scale; integrating both supply-side and demand-side approaches; taking an intersectoral approach to decision making;improving and integrating policy, regulatory and institutional frameworks; and promotingequitable access to water resources through participatory and transparent governance.

IWRM looks outside the narrow "water sector" for policies and activities to achievesustainable water resources development. Focus areas for IWRM are water resourcesassessments, socio-economic assessments, water resources planning, implementation ofaction plans, day-to-day water resources management (adjustments of the plans) and waterresources protection and conservation. Flood and water-related disaster management is across cutting issue that touches upon all of these aspects. Given the holistic approach,IWRM takes into consideration several aspects besides water governance. These include:

• Water supply and health, e.g., sanitation systems and water-borne diseases • Water and agriculture, e.g., water productivity and agricultural practices degrading

water sources• Water and biodiversity, e.g., wetland loss and the need of water for ecosystems• Water and energy, e.g., hydropower potential• Water-related disaster reduction and response, e.g., floods and droughts

Sources: USAID Water Team: Integrated Water Resources Management - A Framework for Action in Freshwater and Coastal Systems,April 2002 and Global Water Partnership, GWP: ToolBox Integrated Water Resources Management, Stockholm 2001.

13

Socio-Economic Aspectsof Water-Related Disaster Response

1

14

Disaster managers must recognize thatdifferent social groups have different needswhen a disaster occurs. Generally,marginalized groups have less social powerand fewer economic resources and physicalcapacity to anticipate, survive and recoverfrom the affects of massive floods. There isan intrinsic relationship between poverty andvulnerability. In addition, the elderly, thedisabled and children are particularlyvulnerable, and gender is especiallyimportant to flood risk reduction.

Poverty

Poverty is a key dimension of any initiativein flood disaster risk management. Povertyaffects people's capacity to protectthemselves and their assets, as well as theirability to live in areas having less exposure torisk. Annually, floods cause great loss of lifeand severely affect large populations. Thepoor are the most severely affected by allnatural disasters, as shown in Figure 5.From 1975 to 2000, people who belong tothe low-income category accounted forabout 50% of those killed in floods (seeFigure 6), with over 90% of all deaths from

natural disasters being attributed to water-related disasters.

Disaster vulnerability and poverty aremutually reinforcing. Factors such as lowincome, poor housing and public services,lack of social security and insurancecoverage force the poor to behave in waysthat expose them to greater risk. As theimpacts of natural disasters tend to falldisproportionately on the poor, specificpolicies are required to tackle the linkbetween poverty and disaster vulnerability.It is very important to link disastermanagement to poverty reduction. Thefailure to properly address livelihood issueshampers advancement on mitigating theimpacts that result from natural disasters.

Creating diverse income-generatingopportunities is an essential element ofsuccessful flood disaster risk management.While simple access to resources such asland is important, ignoring the full dynamicsof a successful local economy can bedisastrous. According to the World DisasterReport 2001, soft infrastructure, includingtraining and work-and-life support services

1.1 Social Aspects of Disaster Reduction and Response

Figure 6

Number of people killed in floods by income class, 1975-2001

Source: ADRC and EM-DAT, CRED, University of Louvain, Belgium

Low incomeLower middle income

Upper middle incomeHigh income

46 105 (26%)

40 930 (23%)2 589 (1%)

84 710 (50%)

Number of people killed in floods by income class, 1975-2001

15

Guidelines for Reducing Flood Losses(e.g., educational and health services,childcare for working mothers), acquires anequal if not greater importance than its hardequivalent of buildings, roads and bridges(IFRC, 2001).

Gender issues

The gender issue requires special attentionin defining the community structures fordisaster response. Women and children,being the most vulnerable groups of thesociety, tend to be most affected by naturaldisasters. There is a strong link between thewell-being of children and that of women.Improving the situation of women is the bestway to advance the survival and recovery ofchildren.

Gender inequalities with respect to humanrights, political and economic status, landownership, housing conditions, exposure toviolence, education and health, make womenmore vulnerable before, during and afterdisasters. Women often diedisproportionately in disasters, if they do notreceive timely warnings or other informationabout hazards and risks, or are preventedfrom acting on them. Their mobility indisasters may be restricted or otherwiseaffected due to cultural and social constraints.Gender-biased attitudes and stereotypes cancomplicate and extend the time for women'srecovery, for example, if women do not seekor do not receive timely care for physical andmental trauma experienced in disasters(United Nations, 2001).

The need to stimulate communityinvolvement and empowerment of women atall stages of disaster managementprogrammes is an integral part of reducingcommunity vulnerability to natural disasters.

However, women's abilities to mitigatehazards, to prevent disasters, and to copewith and recover from their effects have notsufficiently been taken into account nordeveloped (United Nations, 2001).

It is critical to understand the genderdimension in the development-disasterprocess in order to address root causes andtake risk reduction measures that areequitable and efficient. At the mostfundamental level, gender is a centralorganizing principle in the specific culturesand societies in which risk is constructed anddisasters unfold. Gender patterns alsomanifestly shape development patterns andsocial vulnerability to natural disasters(United Nations, 2001).

Pho

to: C

. Bla

ck a

nd D

. Rev

ol, I

FR

C

Mozambique Flood Catastrophe, 2000With clean water in short supply, many people are forcedto resort to using floodwater for cooking, and the risk ofdisease outbreak is high.

16

1.2 Economic Aspects of Disaster Reduction and Response

The number of major catastrophes and theirtotal damages has greatly increased over thelast decade (see Figures 1 and 2) - a trend thatis likely to continue unless concerted action istaken to mitigate the impacts from naturalhazards. The costs of weather-related disastersin 1998 reached a record high of more than$US 92 billion (Abramovitz, 1999). Moreover,natural disasters have a disproportionate impacton the GDP of developing as compared withdeveloped countries (see Figure 7).

Lack of capital or wealth accumulation overthe long run tends to undermine sustainabledevelopment. Recurrent floods andwindstorms, for example, not only destroynational wealth, but also hinder efforts toaccumulate physical and human capital.

Valuation of losses

It is important to assess disaster impacts to helpgovernments adjust their financial planningscenarios and economic growth rate projectionsto offset or reflect the social, economic andenvironmental impacts of shocks caused bydisasters. Such assessments also help to further

our understanding of the importance ofmitigation measures. It has recently beenestimated that for every $US 1 spent formitigation, there is an $US 8 reduction in losses(Abramovitz, 2001).

However, there seems to be a prevailing lack ofsupport from governments to provide resourcesto vulnerable communities. There are severalpotential explanations for this. First, it ispossible that economic decisions are sometimesmade in a manner that stresses short-term

benefits and costs. If, however, a long-termperspective is taken, the benefits of

preventing, minimizing or responding to water-related hazards are clear. Second, it is usuallydifficult to include environmental and socialimpacts to economic calculations, even if theimportance of those impacts is recognized.

There is still a need for standardization of theassessment of economic, social andenvironmental losses for comparative purposes,and for an approach that reflects the reality onthe community level. When assessing the losses,it should be taken into consideration thatcalculating the losses in US dollars might notaccurately reflect the different value andpurchasing power of local currencies.

Insurance

Risk sharing and risk transfer at national,community and household levels can also helpto reduce overall losses, improve resiliency andcontribute to expeditious recovery (UN/ISDR,2002). Insurance can be one tool to improve thesituation of individuals by compensation. Ithelps spread the risk of disaster across society.For example, in Mozambique insurancecompanies and banks are active participants inthe national disaster management system.Lending institutions can also play a differentrole by encouraging implementation ofmitigation measures. Mitigation efforts are a

Figure 7

Disaster losses, total and as share of GDP,in the richest and poorest nations, 1985-1999

Source: Adapted from Munich Re, 1999

Economic losses as percent of GDP Economic losses (billion US$)

Richest Nations Poorest Nations

Billion US$ Percent of GDP

0

2

4

6

8

10

12

14

16

0

100

200

300

400

500

600

700

17

Guidelines for Reducing Flood Lossesform of protecting against future potentiallosses. Lowering risk can help lower the ratesfor insurance, thereby making it moreaffordable for the people. Rates should reflectthe mitigation measures undertaken by thecommunity and individuals (e.g.,implementation of flood plain developmentpolicy and plans, flood proofing, forecastingand warning systems, and real-timemonitoring).

The amount of catastrophe insurancepurchased in the world insurance markets hasincreased enormously. For example, in 1997catastrophic excess of loss coverage (the mostcommon type of catastrophe reinsurance)purchased amounted to $US 52.9 billion. Thisindicates an increase of 34% in three years.Unfortunately, the benefits of this insurancewere reaped almost entirely by the developedworld. The United States, United Kingdomand Japan accounted for 55% of the total(MacKellar et al., 1999).

By contrast, developing Asia, whichrepresented half of all the damages caused bynatural catastrophes and two-thirds of all thecasualties from catastrophic events in 1997,"owned" only 8% of the insurance coverage forcatastrophes purchased in the world market.This coverage sufficed to absorb only 13% ofthe losses incurred. The remainder of thesecosts fell either to the government or victims,with some limited relief from international aidagencies (MacKellar et al., 1999).

The efficiency of risk-sharing and risk transferdepends upon the size of the risk pool andavailability of financial instruments andservices. In developed countries, governments,corporate entities and individuals engage inrisk-sharing, which increases the size of riskpool, thus improving insurability of propertiesand assets. In developing countries, the size ofthe risk pool is smaller, resulting in inadequateinsurance coverage and pay off. A relatedrequirement is the commercial application of

specific instruments and services for risksharing at different levels (UN/ISDR, 2002).

Insurance schemes need to be complementedby other low-cost risk sharing mechanisms inpoorer communities, such as kinshipnetworks, microfinance and public worksprogrammes to increase coping capacities.Additional tools and financial incentives arenecessary to promote proactive disaster riskreduction investment. It is also important thatall development projects include anassessment of vulnerabilities and risks fromdisasters (i.e., a risk management component).The policies and programmes meant forreducing risks from disasters should beincorporated into poverty reductionprogrammes (UN/ISDR, 2002).

Insurance can be used at the national,community and household levels, whilemicrofinance services are only provided at thecommunity and household levels. Publicworks programmes have their own specificcontext, and they can be undertaken toprovide relief to households and communitiesstruck by situations in which there are noincome-earning opportunities. There can be agreat deal of variation in their forms andapplications. It is also likely that in a givensituation a combination of these instrumentsmay be required (UN/ISDR, 2002).

At the national level, improvements in theregulatory frameworks for disaster reductionand response, including disaster-relatedinsurance, building codes and land useplanning, will help ensure that infrastructureis properly sited and built to minimizedamages as well as to reduce the costs ofrepair. This involves public insurance policy,market and regulatory incentives for risk andvulnerability reduction, protection againstfluctuations in insurance/reinsurance prices,augmentation of insurance coverage atreasonable cost, and backstop financialmechanisms (UN/ISDR, 2002).

18

1.3 Response Strategies

Confronting global warming requires theenhancement of international cooperation,and the linkage between disaster reductionand poverty alleviation necessitates theinvolvement of all stakeholders at the local,national, regional and interregional levels.The present era of globalization has helpedincrease awareness that water-relateddisasters can happen in any society. There isan increasing recognition of a number ofopportunities and approaches for buildingstrategic alliances and partnerships amonggovernment institutions, private sectororganizations, civil societies and otherstakeholders to pursue the goal of sustainableeconomic development and IWRM.

There is a growing realization that variousflood mitigation measures must be combinedin ways that are appropriate to effectivelyaddress local situations. A balance betweenstructural and non-structural measures tomanage floods and reduce losses is required,where the emphasis is shifting from largestructural solutions to innovative measures inflood proofing and improved building codesto non-structural flood measures such asland use regulation, flood plain management,compensation schemes, insurance schemesand the improved participation of localcommunities prone to flood hazards. Thevalue of community-based forecastingsystems is recognized in reducing loss of lifeand decreasing economic losses, as theymake use of local empirical knowledge aswell as increase local capacity for reducingcommunal vulnerability to floods.

The flood disaster management processshould also be coordinated with efforts madein closely related fields. For example, thedisaster mitigation process should considerhuman health impacts during flooding (e.g.cholera, e-coli, malaria), thereby moreeffectively addressing health issue that ariseduring flooding.

Community level

Community-based disaster management isessential for numerous reasons. First,communities are the ones who suffer the most.Second, community-based organizations actfaster in responding to disaster before thearrival of external help. Third, localmanagement leads to securing local supportand ownership.

Community involvement is also needed inplanning for disaster management, because inmany cases there is a missing link between thedisaster response actually needed and what isprovided. In general, after the disaster hasstruck, responses are provided and managedat different levels in the form of relocation andzoning strategies, infrastructure rehabilitation,and restructuring of early warning systems.The problem is that most of the floodmitigation strategies are top-down in nature.Communities have no role in either theplanning of disaster management, allocation ofresources or implementation of the plan.

Community-level organization, managementand empowerment are essential to mitigate theaffects of disasters. Community structuresneed to be formalized, and their role andcapacities in disaster managementstrengthened. The government and non-government institutions should work withcommunity structures. In general, communityorganizations serve as an important bridgeand instrument to link the ground-levelresponse to a higher level of decision-making.

It is important to coordinate civil societyaction with government mitigationprogrammes. Reduction in future losses willdepend on the ability of all levels to worktogether on preventative measures, to actjointly in the face of disasters, and to be ableto draw on contingency plans.

19

Guidelines for Reducing Flood LossesAn example of community level involvementis provided in Case Study 1 in the Annex. Itdescribes approaches taken in the Philippinesfor preparing a community for disasters.

National level

Most countries are now recognizing theimportance of dealing with floods in thecontext of IWRM and the need for abalanced approach to optimize the beneficialeffects while minimizing the disastrouseffects of floods. Two aspects have beenidentified as being necessary in floodmanagement at the national level. The firstis the need to introduce multi-hazardmanagement systems, includingcoordination and response mechanisms. Thesecond is the need for end-to-end disasterrisk management of water-related disasters.

A major constraint to successfully being ableto mitigate the effect of flooding is thefragmented institutional structures and lackof coordination and cooperation that canexist among national institutions. This canresult in a general lack of planning andcommitment to implement disastermitigation activities.

Countries need to establish a clear nationallead agency responsible for flood disastermanagement. Countries need to assess thelevel of additional inputs needed fromgovernmental and non-governmentalorganizations as well as from organizationsrepresenting the civil society. There has beenan encouraging trend of governmentcommitments to establish early warning andflood forecasting systems and to expandflood forecasting and management to covera larger portion of national populations.Countries that currently have little floodmanagement capacity recognize theimportance of improving effective systems toprotect the lives and property of theirpopulations. It is extremely important to

integrate the flood disaster managementprocess into social and economicdevelopment plans of the country.

Regional level

A special challenge is posed to floodmanagement and disaster reduction andresponse in shared river basins. Moreregional cooperation is needed. Countriesare encouraged to take full advantage ofregional capacity. The exchange of relevantdata and information related to hydrologicaldata, hydrological forecasts, weatherforecasts, reservoir operation as well asmajor changes in land use and water usemanagement are important steps toimproving flood disaster reduction andresponse of riparian countries in sharedriver basins. Consideration should also begiven to regional training programmes anddisaster assistance.

Regional collaboration is also a distinctpossibility to foster data exchange, todevelop common communication andforecast methodologies, and to exchangeexpertise. In this fashion the resources of agreater geographical area can be brought tobear as backup during extreme stormevents.

Smaller countries may give consideration tobilateral arrangements with larger partners,or to develop joint activities withneighbouring countries. The latter is adistinct advantage when transboundarybasins are involved or the goal is to increasejoint scientific and technical abilities.

One good example of regional cooperationin Asia and the Pacific is the TyphoonCommittee. It covers East and SoutheastAsia and the North Pacific and has existedfor 35 years. It was jointly established in1968 under ESCAP and WMO auspicesto coordinate efforts among countries of the

20

region in predicting and monitoringtyphoons and thus reducing losses. TheCommittee provides advice onimprovements to forecasting andcommunity preparedness and preventionactivities, promotes research and training,and facilitates identification of fundingsources.

1.4 Public Awareness and Communication

Communities should not be passiverecipients of information. There is a need toencourage people to help themselves, andcommunities must be provided with themechanisms and tools to do so.Communities need to be active in theinformation dissemination system. Theyrequire technology adapted to local needsand conditions. Local communities shouldalso be encouraged to document disastersand events at their level in any way possiblefor future research on flood mitigation andto increase local empirical knowledge offlooding.

There is a need to distinguish betweeninformation, education, and communication.For example, a forecast of water level by thetechnocrat may not be meaningful to thetarget groups. The forecaster and the peoplemust be educated so that the message isunderstood by the various users, e.g. what todo when water level is classified asdangerous. Next comes the means tocommunicate to the target groups. Besidesusing the mass media, effectivecommunication may include influentialpeople such as local politicians andtraditional leaders, whom the communityrespects.

Activities may also be targeted at children.Case Study 3 in the Annex describes atraining project to introduce disaster

awareness and preparedness to theelementary school system in Vietnam. Thisapproach also helps to foster a greaterawareness of natural disasters within familiesand their communities.

Flood warning systems andcommunication methods

The operation of a flood warning andresponse system is the most effective methodfor reducing the risk of loss of life andeconomic losses. This is particularly sowhere the unplanned occupation of flood-prone areas has taken place or where sectorsof the community are vulnerable to floodingunder extreme conditions. It is veryimportant to link indigenous knowledge ofbasin response to forecasted or observedweather conditions. In some cases localcommunities may be unaware of weatherevents occurring upstream of their locationthat might well result in their destruction.People in communities need to understandwhat a prediction means: how exactly thepredicted event would affect thempersonally. These predictions have to beapplicable to people having varyingeconomic status and reflect genderdifferences so that all elements of society canunderstand what response actions should betaken. Also, the flood warning and responsesystem should be promoted in such a waythat an "ownership" sense is created within

Another example of regional cooperation isprovided in Case Study 2, which iscontained in the Annex, on the SouthAfrican Development Community (SADC).The Case Study provides information on therecent developments on regional cooperationfollowing the devastating flooding thatoccurred in the region in 2000 and 2001.

21

Guidelines for Reducing Flood Lossesthe communities that operate the system tofoster its sustainability. Special considerationshould be given to language and culturalbarriers to increase the effectiveness of thesystem.

A number of low-cost solutions could beused at the village level to enable localpopulations to foresee a coming flood. TheAfrican Centre of MeteorologicalApplication for Development (ACMAD)takes advantage of the human resourcecapacity at the village level to reduce risk.Novel communication methods includingwind-up radios and translation of forecastproducts to the village level have helpedfarmers reduce the impact of climate-relatedhazards. Local authorities are using acombination of high technology (datadisplay and exchange using the Internet)and basic technology at the local level toinform communities about potential effectsof drought or flood. Regional capacitybuilding workshops help participantsproduce forecasts, enabling them to returnto their home countries and update localforecasts. Small resources for small projectsrely on large human resources at thecommunity level, thereby effectivelymagnifying the effectiveness of theinvestment. Case Study 4 on Access to

Information provides additional details onmaking information available to thecommunity level.

Public education

An effective public awareness programmecan contribute a great deal to reducingdisaster-related losses. When developingsuch a programme, it is important that theseriousness of the risk is accuratelyperceived and that information becommunicated with the appropriate level ofurgency. Also risk communication should beviewed as a continuous process, where thecontents of the message should becontinuously reviewed and improved.Finally, the messages should be kept assimple as possible. There should be adesignated lead agency for developing andissuing such messages.

Both formal and informal means of educationshould be used. Public education must bedirected towards all levels - political leaders,bureaucrats, and the most vulnerablecommunities. For example, politicians andbureaucrats should consider shifting fundingpriorities from emergency aid to preventivemeasures. Currently, it is difficult to obtainfunding for preventive measures.

23

Key Elementsof Flood Disaster Management

2

24

2.1 Risk Management and Flood Plain Delineation

A change to proactive management ofnatural disasters requires an identification ofthe risk, the development of strategies toreduce that risk, and the creation of policiesand programmes to put these strategies intoeffect. Risk management is a fundamentalactivity geared to the evaluation of schemesfor reducing but not necessarily eliminatingthe overall risk, as in may cases risk cannotbe entirely eliminated. Figure 8 provides aschematic of the steps associated with riskassessment and management. It includesassessing the potential for a hazard to occurand a vulnerability analysis to provide anunderstanding of the consequences shouldan event of a certain magnitude andfrequency occur. Based on this initial work,various mitigation measures can beevaluated to assess their ability for reducingrisk exposure. Based on a thorough riskassessment, disaster management plans andspecific mitigation measures can be

identified. Efforts would then be undertakento implement the selected mitigationmeasures.

For flooding events, there is a need tocalculate the probability or likelihood that anextreme event will occur and to establish andestimate the social, economic andenvironmental implications should the eventoccur under existing conditions. Maps of theflood-prone areas should be prepared anddetailed impacts outlined. A participatoryprocess should be invoked, leading to thedevelopment of an acceptable level of risk.Measures can be evaluated and implementedto meet this level. This overall process assiststhe community in better understanding thevarious actions that can increase or decreaserisk exposure, and can lead to greatercommunity participation in the developedsolutions to the flooding problem.

Figure 8

Framework for Flood Risk Assessment and Risk Management

Source: Adapted from WMO, 1999

Natural System ObservationsInventory

AccountingData

Thematic Event Maps

Establish FloodHazard PotentialStreamflow versus

Probability of Occurrence

Risk AssessmentRisk = function (Hazard, Vulnerability, Value)

Planning / Mitigation Measures

Reduce Risk Through Best PossibleManagement Practices

> Land use Planning (Flood Plain Mapping)> Structural Measures (Dams, Building Codes)> Flood Forecasting and Warning Systems

Assess VulnerabilityValue (Material, People)

InjuriesResiliency

Protection Goals / Risk Acceptance

Unacceptable Risk Acceptable Risk

Implementationand

Periodic Review

25


There may be a necessity to define severalzones within the flood-prone area, dependenton the velocity of the river and other physicalfactors. As an example, the flood-prone areamay be broken down into floodway and floodplain components. Figure 9 shows aschematic of the designated floodway andflood plain for a hypothetical community.

Delineation of the flood-prone area

In order to map and delineate an areaaffected by floodwaters, there is the need toselect a "design" event. Various approachesfor estimating the design event exist, basedin essence on "acceptable" risk, although atthe time of their adoption, the concept ofacceptable risk was not explicitly recognized.These approaches include using a historicalworst-case scenario that happened in thebasin or could plausibly have happened,which is referred to as storm transposition.Another approach is to theoreticallymaximize the meteorological factors thatcould happen in an area leading to the worstpossible storm producing the worst possibleflood. These are termed the Probable

Maximum Storm and Probable MaximumFlood, respectively. The third approach is touse a probability-based analysis whereinsystematic records and historical informationon past flooding are used to develop arelation of probability of occurrence versusmagnitude. It is becoming popular to adoptthe concept of acceptable risk rather thanadopting preset levels of protectionassociated with a specific probability ofoccurrence (e.g., the 100-year flood). Acommunity and its government may wish tomove to more extreme design levels whenfaced with the reality of future loss-of-lifeand extreme economic hardships when thefuture event occurs.

The frequency based approach is thepredominate method used in most floodplain delineation studies when the potentialfor loss of life is considered negligible interms of historical floods. The peak flooddischarge and corresponding water level areestablished for various frequencies ofoccurrence or return periods of events suchas once in 25 years (1:25), 1:50, and 1:100.Associated estimated damages are

Designation of floodplain and floodway components

Sour

ce: E

nvir

onm

ent C

anad

a

Figure 9

26

established for each probability. Manyjurisdictions have set their design level tothe "100 year flood". Statistically it is quitepossible to have more than one "100 yearflood" within a 100-year period, and a moreextreme event can also occur at any time. Areasonable length of streamflow record isrequired to ascertain with some accuracy theprobability of an event occurring.

When using a known historical flood todefine the flood-prone area, various effortsare required to delineate the flood plain. Thisapproach can at times rely on surveyinformation collected during or immediatelyafter the historical flood event. These datacan be used to verify hydraulic modelinformation to ensure accurate delineation ofthe flood plain. In cases using historicalfloods, care should be taken to adjuststreamflow and water levels to reflect thepresent levels and possibly projected levels ofdevelopment in the basin or other physicalchanges in the waterway. When a historicalstorm is transposed, hydrological models areused to transform rainfall to streamflow, andhydraulic models are, in turn, used todelineate the flood plain.

A shortcoming of using a known extremeflood event is the difficulty of assigning afrequency of return for evaluation of risk.However in data-short areas or when theevent can cause catastrophic results, it isprobably the preferred approach. It is alsouseful in establishing acceptable levels ofprotection.

These approaches tend to assume that eventsin the future are predictable based on theexperience of the past. If changes in land useare occurring, this may not be true, and thechanges should be reflected in the analyses.Similarly, the impacts of climate change orvariability are not typically being incorporatedin the analysis. If possible, such factorsshould also be taken into account in thedelineation of flood-prone areas.

Floodway and flood plain

The floodway is that portion of the flood-prone area that is required to pass the designflood event without a significant rise inwater levels compared to undevelopedconditions. "Significant" is normally definedas a rise in the range of 25 to 40 cm. Thefloodway is delineated using the floodfrequency or extreme event informationcombined with a hydraulic analysis.Normally the floodway can be characterizedas that part of the flood-prone area havinghigh velocities, high potential for erosion,and high exposure to significant flow ofdebris. Often the floodway encompasses thenormal river channel and some expandedhigh water area. No structures, other thancritical infrastructure such as bridges,should be allowed in the floodway. Insimple terms, the floodway is reserved forthe river, not for humans.

The flood plain is the residual area outside ofthe floodway where the water velocities areless and flood protection and flood-proofingmeasures can be considered. When both thefloodway and flood plain are identified, this ittermed a two-zone approach. A simplified orone-zone approach is, at times, used whenthere is no existing incompatible developmentin the floodway and no new incompatibledevelopment will be allowed in the future. Insuch cases, only one designation of zone isused, and the entire area is treated as a floodplain. Under such circumstances, care wouldbe taken to ensure that no new incompatibledevelopment occurs in the zone.

Figure 10 shows a section of a map for a one-zone application where the flood plain isdesignated in its entirety. The map showshomes, businesses, and institutions at risk at a1:2,000 scale. Land contour information at 1-metre resolution is provided. Implications onexisting and future land use (e.g., residential,parkland, industrial) would be set throughpolicy and would be reflected in local zoning.

27


Implications on existing investments wouldalso be set by policy, which could consideroptions such as relocation of incompatibleuses, adoption of flood-proofing measures, orchanges in designation of vacant or unusedlands.

Areas beyond the defined flood plain may besubject to flooding by even rarer events,which are events that exceed the design event.Efforts should be made to ensure that"critical facilities" are flood proofed againstthese rarer events. Critical facilities includehazardous materials production, storage andwaste facilities; essential utilities such as waterand wastewater facilities and power plants;essential services such as hospitals, schoolsand airports; and emergency services such asfire stations or major computer centres. Forexample, if the 100-year flood is used todefine the flood plain for zoning purposes,then critical facilities could be flood proofedto higher standards as if they were in the 500-year flood plain.

Vulnerability analysis

A vulnerability analysis considers thepopulation and structures at risk within theflood-prone area. The analysis evaluates thepotential costs of flooding in terms ofdamages to buildings, crops, roads, bridgesand critical infrastructure, such as utilities.Normally the analysis is carried out forvarious probabilities of floods, and anelevation-damage curve is developed.

A vulnerability analysis, because it identifiesthe population at greatest risk, can also beused to identify the emergency responsesthat may be required, including the need fortemporary shelters and evacuationrequirements.

The analysis is also valuable for making adecision on the level of flood protection. Thedecision is based on knowledge of the degreeof cost effectiveness of various options.However it should be a public process that

Sour

ce: E

nvir

onm

ent C

anad

a

Section of map showing designated flood plain areaFigure 10

28

establishes the "acceptable level of risk" thatleads to the return period appropriate for thedelineation of flood-prone areas. The analysismay also generate information useful indetermining the benefits of flow forecasting.

Flood risk mapping

Mapping defines the area at risk and shouldbe the basis for all flood damage reductionprogrammes and subsequent actions. Themaps often have a legal connotation in termsof zoning and other structural and non-structural measures undertaken, so theyneed to be accurate and credible.

The mapping is normally based on afrequency of flood event determined bypublic consultation and reflected in policy,which may be based on a vulnerabilityanalysis that is site specific. If regional ornational flood reduction programmes are inplace, there are advantages to a commonmapping standard. If the historical flood isused, then some attempt should be made toassign a return period to the event forcommunication and design purposes.

Maps become the common element in termsof identification of flood-prone areas,identifying the risk to individuals andlending institutions, preparation ofemergency response plans, and design offlood protection and flood proofing

measures. Perhaps their greatest value is asan educational and communications tool,and they should be readily available to thepublic as well as to emergency responseagencies at all levels of government.

Through modern computational systems,inundation maps can be generated in real-time and be part of the hydrological forecastsystem. These can greatly assist incommunication to residents in areas ofpotential risk, and in planning responseactions and assistance.

Protecting flood-prone lands

Policies and programmes to keep futureflood damages from rising are based on thedelineation and mapping of flood-proneareas. Generally the resulting programmeswill mean some form of control over newdevelopment in the flood-prone areacombined with measures to reduce damagesto existing development. Such programmesare needed to curb the rising social andeconomic losses that results from floods.

Alternate use of flood-prone land should beconsidered where possible. It is better tohave the land zoned and used for purposessuch as parks, nature areas or ecologicalreserves than to try and ensure that futuredevelopment is flood proofed. Zoning andflood proofing measures can be used tocontrol development and reduce future flooddamages, but the effectiveness of suchmeasures is highly reliant on enforcementand maintenance. Local authorities aresubject to developmental pressures andstandards have a tendency to "slip" as thememory of a flood event fades.

Climatological forecasting

Climatological or seasonal forecasting hasnow advanced to the point of being a usefultool in reducing the risk of flooding.Extreme events are correlated to major

Pho

to: I

nter

natio

nal A

ssocia

tion

for C

hrist

ian

Actio

n, I

taly

29

Guidelines for Reducing Flood Losseschanges in atmospheric and oceancirculation patterns, and once suchpatterns have been identified, thepotential for a lesser or greater degree ofstorm activity can be forecast. Thisinformation can then be used to increasethe degree of readiness of emergencyresponse and forecasting agencies.

In certain cases the climatic forecasts canalso be used to increase the availability ofstorage in reservoirs, to influence watermanagement decisions and to create anawareness of the potential for flooding.All of these measures can reduce theseverity of flooding, if it occurs.

When the probability of the extremeflooding event is greater than normal,then activities such as the stockpiling ofsandbags, emergency food and watersupplies, and the evacuation of highvalue stored crops or goods from flood-prone areas can be undertaken. It is agood time to create awareness in thepublic as to the potential for flooding,highlight the actions that the public andothers should take, and to carry outemergency response exercises to test thedegree of readiness. In some casesemergency measures such as temporaryraising of flood protection works may bewarranted.

China, Yangtze River, 1998

The photograph depicts Chinese soldiers and civilians struggling tomaintain weakened levees during the summer floods of 1998.

It has become almost an annual occurrence: China'smighty Yangtze River swells under torrential rains, thensurges downstream, flooding dozens of communities andleaving thousands homeless. During the summer of1998, more than 2,000 people were killed, and thefloods, which began in early June when seasonal rainsarrived earlier and were heavier than usual, left 14million homeless. For the fifth time that summer, theYangtze hurled a massive flood crest toward the tens ofmillions of people who make their homes along its centraland lower stretches. Earlier that week, a fourth floodcrest was thwarted by millions of weary soldiers andcivilians drafted into the flood-fighting campaign. Moreimportantly, weakened levees that have withstood an earlyconstant assault by the river remained largely intact.

Pho

to: X

inhu

a N

ews A

genc

y

30

2.2 Supportive Technologies

A number of tools are available to array anddisplay information for the use of technicalexperts, to explain programmes of flooddamage reduction to the decision-makers,and to communicate real time forecasts andwarnings to the public. In general the toolsshould be interactive in the sense that theinformation can be easily updated, andflexible enough to develop scenarios, and toprovide visual and quantitative informationregarding the state of conditions during theforecasted event.

Geographic information systems

Geographic Information Systems (GIS)provide a computer-based information andmanipulation system useful in support offlow forecasting and emergency response.Information from a variety of sources andscales can be combined as a series of layers,provided that the information can beidentified in terms of the commondenominator of location. For example,information on vegetative cover can becombined with soils and land slopeinformation to estimate infiltration rates forforecasting purposes. Similarly layers ofutility, land use, flood plain delineation, andstructures information can help in thedevelopment and updating of emergencyresponse plans.

A good representation of the basintopography is an important asset in floodforecasting, emergency action andmitigation. A digital elevation model(DEM) or digital terrain model (DTM) forthe basin should be developed as part of anyGIS. Technologies exist that enable theconstruction of a "seamless best available"DEM. In other words the DEM isconstructed from whatever topographicinformation is available. Parts of the basinor certain features may be very accurate

while others may be quite basic. The DEMcan be improved with time.

The development of inexpensive globalposition indicators has made GISinformation easier to obtain. For example,data network sites, buildings or physicalfeatures can now be easily located withprecision and at low cost. Land use,vegetative cover or soils information is alsoeasier to assemble.

Mapping

Maps of areas at risk from natural disastersare valuable information and communicationtools. They can be used for a wide variety ofpurposes ranging from flood plaindelineation, zoning and land use planning topresentation of information at publicmeetings.

Zoning maps, however, are static and mayrequire updating with time as changes occur.For static information, such as the delineationof the flood-prone area, frequent updating isnot required, and maps are a useful referencetool for a wide variety of users.

Visualization techniques

GIS and other computer-based informationsystems allow for a wide range ofpresentational material to be easily generatedand tailored to the target audience. Three-dimensional displays, zoom and scan, androtational techniques can be combined withother informational material such aspictures, overheads or slides. As anexample, a GIS flood inundation map canbe generated based on hydraulic modelderived information. The map can beconveyed to residents in the flood plain andis useful for depicting the probable impactof the approaching flood.

31

Guidelines for Reducing Flood LossesThis tailoring of technical information intodisplays that are more readily understood isvaluable for explaining programmes todecision-makers, informed experts, and thepublic at large. Highly visual information isparticularly valuable for public meetings oropen houses, but must be tailored carefullyfor the audience. In particular, the

2.3 Flood Plain Management

Management of activities within the flood-prone area can significantly reduce flooddamages to existing development and preventthe amount of damages from rising in thefuture. The most desirable approach is toprohibit new development in the flood plainand to flood proof existing structures, or toreplace the existing development byalternative usage of the land. However,where the amount of present development issubstantial or the flood plain is essential forthe production of food or other key economicactivities, alternate strategies such as floodproofing and protection can be considered.

A. Structural Measures

Construction of dams/diversions/storm channels/levees

Construction of protective works such asflood storage reservoirs, diversion of waterto side channel storage or other watersheds,construction of storm channels to carrywater around the area to be protected, andlevees along the floodway provide tools toreduce flood damages. Such works can beconstructed to various levels of protection,usually based on: 1) minimum standardsfor flood protection; 2) the optimum levelof costs and benefits based on an economicanalysis; or 3) to meet established levels ofacceptable risk.

Protective works should be consideredwhen major infrastructure has already beendeveloped and costs to protect existinginvestments are far less than those relatedto reconstruction, lost economic activity,disaster assistance, or relocation of existingstructures and activities. For example, floodprotection measures for the city ofWinnipeg, Canada, were completed in thelate 1960s at a cost of $US 92 million. Arough estimate of damages prevented infive large floods since then is approximately$US 2.0 billion.

Protective works have a tendency toincrease the level of development in flood-prone areas, as the assumption is made thatit is now safe to build and invest in areasthat are protected. However, it must berecognized that at some point in the futurethe design event will likely be exceeded andcatastrophic damages will result. Leveesand storage dams are particularlydangerous when design thresholds areexceeded in that unexpected failure canresult in a rapid rise in water level andmake evacuation and emergency protectionextremely difficult. Diversions or stormchannels are less prone to catastrophicfailure and the level of protection cantemporarily be increased by emergencymeasures if the lead-time of the floodwarning is sufficient.

information must be credible and easilyunderstood.

The above techniques, combined with theflood forecast, provide a very effectivemeans of delineating areas at risk and forcommunicating this to the decision-makers,emergency response teams, and the public.

32

Flood control storage may be onecomponent of a multi-purpose reservoirdevelopment. Over time the operation ofthe reservoir could be altered to enhanceother beneficial uses of storage to thedetriment of flood control. A commitmentto "designated flood storage" and toreservoir operation procedures to achievethat storage is needed.

Inspection, rehabilitation andmaintenance

Structural works require a periodic andsystematic inspection, rehabilitation andmaintenance programme to ensure that thedesign capabilities are maintained. Forexample, levees may be subject to weakeningdue to erosion during a past flood event, bythe actions of burrowing animals, or theconstruction of utility lines through thelevee. Of particular importance is aninspection programme and responsibilityassigned for rehabilitation and maintenance.

Structures such as dams should be subjectto a dam safety programme, usually at thenational level, to ensure that the specializedexpertise required is available for theinspection of all structures. Dam safetyprogrammes are carried out in manycountries and standards or guidelines arereadily available.

Flood proofing of new and existingstructures

Any new construction permitted in theflood plain should be flood proofed toreduce future damages. Building codescan be developed that minimize flooddamages by ensuring that beneficial uses ofbuildings are located above the designflood elevation. For example, buildingscan be raised above the design flood levelby placement of fill; stilts or piles used toelevate the structure; and building utilitiescan be located above the flood level (see

Figure 11). Ground floors can bedesigned in a way that little flood damageoccurs through use of masonry materialsand specifying that contents must beremovable.

If any new development is allowed withinthe flood-prone area, then the impact ofthat development must be taken intoaccount to ensure that flood levels do notrise significantly due to the additionalconstriction to flow. Hydraulic analysescan be undertaken to ascertain the impactsof potential activities and to keep the riseto within acceptable limits.

Flood proofing of existing structures isdifficult and expensive. One successfulstrategy is to link flood disaster assistanceavailable after a flood event to methods ofreconstruction that minimize future flooddamages. This approach often requiresadditional funding over and above apayment for damages, but can be cost-shared between various levels ofgovernment and the owner. This strategyis particularly useful when flooding isfrequent and future disaster assistance canbe expected as part of disaster policies.

Flood proofing of existing structures caninclude raising of structures to preventdamage, relocation of utilities, changedbuilding use, installation of protectivewalls and waterproof closures, and use ofmaterials that are not damaged by waterand can be easily cleaned after the floodevent. Relocation of existing buildings andstructures to an area that is not flood-prone is also an option.

Buyout and relocation programmes for aparticularly vulnerable development shouldform a component of flood proofinginitiatives. In many cases it may be moreeconomical to buy out and relocate theexisting use than to protect it.

33


A number of critical services such aswater lines, power pylons and telephoneservices often cross the flood plain.These utilities can be protected againstthe ravages of flooding at relatively lowcost through additional depth of burial,a higher design standard for exposedcomponents, and raising of componentsabove design flood levels.

Water supply and treatment plants areparticularly vulnerable. They are oftenlocated on the flood plain yet are criticalfor the protection of human healthduring and after a flood event. Suchstructures need to be protected againstextreme events and designed to preventcross-contamination from floodwaters orsewers.

Bridges and roads

Bridges generally constrict the flow of water,and they can act as artificial dams if debrisjams on the structure. In all cases, theirhydraulic characteristics must be considered atthe design stage to prevent an unacceptablerise of water levels upstream of the structure.

Bridges are important in terms ofmaintaining access for evacuation anddelivery of medical and other emergencyservices. Key transportation corridorsshould have high design standards that willwithstand extreme flooding events.However not all bridges require a high levelof protection, and the design criteria can beto a lesser standard that takes intoconsideration the possibility of overtopping.

Figure 11

Flood proofed dwelling

Pho

to: E

nvir

onm

ent C

anad

a

34

Bridges are expensive, and difficult toreplace quickly after a flood event. Analternative strategy is to design the approachroads to be the weak link in the chain so thatextreme events wash out the road but do notdamage the bridge. Approaches can bequickly repaired after a flood event andtransportation corridors restored.

Road design, either parallel to the river orleading to bridges, must be given carefulconsideration. There is a temptation to raiseroads that have been overtopped by floodevents without giving adequateconsideration to the number and size ofopenings necessary to pass local drainage ortributary inflow. In such cases the road canartificially raise water levels upstream andcause additional flood damage. Roads canalso act as levees when they are parallel tothe river. This is a two-edged sword: whileflood protection is provided, the water levelupstream can increase, resulting inadditional flood damages there. Hydraulicstudies must be undertaken before roads areraised to fully establish the impacts of theseactivities.

Enforcement of standardsand codes

The enforcement of standards and codes forflood-prone areas is as important as their

initial development. There is a tendency tobend the rules as the memory of a floodevent and its catastrophic consequencesgradually fade away with time.

Enforcement procedures and penalties needto be built into the process, and emergencyresponse drills undertaken to ensure thatflood prevention measures such aswaterproof closures still work. An auditprocedure should be performed by higherorders of government with participation ofall interested parties to ensure broad nationalstandards are being met and that codes andrules are being suitably followed andenforced.

Governments should consider introducingrequirements such as surveyor certificates toverify that design elevations have been met,or inspector reports that flood-proofingmeasures have been implemented. Lendingand insurance institutions could usefully beinvolved in this process, as they have avested interest in ensuring that theirinvestments are protected.

B. Non-structural Measures

Non-structural measures are particularlyapplicable to flood-prone areas that are notyet developed. As such, they are acomplement to structural approaches inareas where additional development mayoccur, and they also represent anindependent approach where some controlover flood plain development can beexercised at low cost. Non-structuralapproaches do not mean "no use", but rather"wise use".

Land-use planning

Land-use planning at the local or municipallevel can be a useful tool in reducing futureflood damages. Consideration should begiven to ensuring that there are conforminguses in flood-prone areas as part of master

Pho

to: D

. Ray

ner,

Geo

Res

ourc

es

In the days and weeks following Hurricane Mitch, people struggledto find even the basic needs such as clean, safe water.

35

Guidelines for Reducing Flood Lossesplans. The land along a river is highlydesirable for parks and recreational uses, aswell as for ecological reserves. Supportiveinfrastructure such as washrooms, picnicfacilities and changing rooms can be floodproofed. Private development of conforminguses such as golf courses can also beconsidered. The important point here is tointegrate the land-use planning for flood-prone lands into the broader plans for theurban and surrounding area.

Zoning of flood-prone lands

The best way to reduce future flood damagesis to prevent development from occurring onflood-prone lands. Zoning of such lands isan effective approach, but generally should becoupled with the broader land-use planningmentioned above so that the land has adefined use.

Zoning can be used to reduce damages fromflooding and be flexible enough to recognizethat other forms of land use are compatible.An example is agricultural use of lands inflood-prone areas where water velocities arelow enough not to cause serious erosion.Flood-prone lands can continue to be usedfor agricultural purposes, particularly incountries where the amount of agriculturalland is limited and self-sufficiency in foodsupply is a national goal. It is important,however, to ensure that the supportinginfrastructure such as buildings and housesare located away from the flood-prone area orare flood proofed. It is also important thatlivestock, machinery or stored crops can beevacuated quickly from the area in the eventof a flood. This underscores the importanceof a flood forecast, warning and responsesystem.

Zoning of flood-prone lands as ecologicalreserves or protected wetlands can often helpto meet broader environmental or biodiversitygoals. In addition, such lands often play animportant role in sustaining the fishery, and

they can also act as temporary storage andinfiltration areas. Riparian buffer strips alsoreduce the movement of agriculturalchemicals and nutrients into the aquaticsystem.

Redevelopment of flood-prone areas

A major flood disaster is sometimes anopportunity to correct the planning errors ofthe past. Removal of flood-pronedevelopment and conversion of the land to aconforming use is an option to consider. Itmay be less expensive in the long run tophysically relocate flood-prone development,buy it out as part of a disaster assistanceprogramme, or include its purchase in longterm planning. The success of the latterapproach can be enhanced by measures suchas prohibiting improvements not required forhealth and safety, placing caveats on the landtitle, and by obtaining rights of first refusalon resale.

Compensation and incentives

Compensation as part of disaster assistanceshould always have as a goal the reductionof future flood damages. Rather thansimply paying for damages, the fundsshould be focused on flood proofing,buyout, relocation and public education onthe risks and consequences of living onflood-prone lands.

Pho

to: M

ing

Pres

s

36

In a similar manner, incentives can bedeveloped that encourage flood proofing orrelocation, and these can be financedthrough cost-shared programmes. Here thecost of flood proofing can be shared inproportion to the benefits to the variouslevels of government of not having tocompensate for future flood damages.Property owners should also be expected topay a reasonable share in view of theenhanced value of a flood-proofed structureand the reduced inconvenience after a flood.

Land exchange programmes can be used asan incentive to relocate from flood-pronelands. In such cases a public entity makesalternate land available and disasterassistance is generally used to pay forrelocation or replacement of structures,depending on the costs and benefits.

Incentives can also take the form ofpenalties. For example, if an individual isaware of the risk of flooding through suchprogrammes as flood plain delineation, orcaveats on land titles, and still decides tobuild on flood-prone land, then that personshould bear the consequences of his/heractions and not be eligible for disasterassistance. However this is difficult toenforce and is reliant on strong political willat the time of announcing disaster assistance.

Insurance

Flood disaster insurance forms part of thesuite of responses to reducing flood lossesin the United States of America. When aprospective homebuyer seeks to purchase aproperty in a designated flood-prone areawith funds obtained through a federally-insured or regulated institution, the lender

is required to notify the borrower of theneed for flood insurance. The lossescovered by flood insurance are paid fromthe accumulated premiums of policyholdersrather than disaster assistance funds.There are some weaknesses in thisapproach, as not all homeowners in flood-prone areas purchase insurance, and thereis the necessity for public funding if lossesexceed the accumulated premiums. Floodinsurance schemes have been utilized inother countries, including parts ofGermany, with varying degrees of success.

For insurance schemes to be successful,there needs to be a clear definition of therisk, as premiums should reflect the degreeof risk at a given location. It is alsodesirable for governments to promote or,when possible, mandate universal insurancecoverage and guarantee funding whenpayouts exceed premiums. Such schemesshould be designed to be self-sustainingover the long term. An additionalproblem concerns the information base,which is seldom sufficient to define thedegree of risk adequately. It is alsodifficult to effectively make insurancemandatory. Often those most at risk due toflooding are the least able to pay, or theyrefuse to pay because of high premiums.

The United States has an advantage froman insurance perspective in that 20,000communities are at risk from flooding; withsuch a large number of flood-pronecommunities, the financial risk can bespread more easily than in smallercountries. Insurance is an option thatneeds to be considered, but is probably notfeasible in many developing countries atthis time.

37


2.4 Watershed Management

The water storage effect of vegetation, soil,shallow groundwater, wetlands and drainagehas a direct impact on the flood level indownstream areas. Each of these storagemedia retain certain quantities of water forvarious periods of time and can influencethe timing of tributary flows and hence theircontribution to a flood event. The storageeffect can be likened to a sponge and isdependent on the antecedent conditions andthe magnitude of the flood.

Impacts of land-use changes

The impacts of land-use changes on floodevents can be both positive and negative, sopredictions are hard to make for a specificwatershed. Generally the removal of forestand other natural cover, and the conversionof land to agricultural uses, compacts thesoil and reduces infiltration rates, leading tohigher flood peaks. Deforestation isbelieved to have been a significant cause ofthe catastrophic flooding in the YangtzeRiver basin in China and in CentralAmerica from Hurricane Mitch, both in1998. Deforestation and other land-usepractices can also lead to greater incidencesof landslides and mud flows.

Natural water storage is also generallyreduced due to the gradual loss of organicmaterial and soil erosion, once an area isconverted to agriculture. Additionally,natural vegetation may transpire moisture tothe atmosphere at a greater rate thanreplacement crops, thereby affecting both

the amount of storage available in the soiland the amount of local rainfall.

Drainage of wetlands and marshescontributes directly to changes in the timingof runoff, the amount of natural storage inthe basin, and the vulnerability of thechannel to the erosive forces of water. Evenroad construction can contribute directly toincreased runoff rates through improveddrainage as well as the effect of reducedinfiltration through the road surface.

By far the greatest impact of land-usechange is associated with urbanization itself.The paving of surfaces significantly reducesinfiltration, natural storage is reduced byimproved drainage, and streams are oftenconstricted by development or crossings. Acity will frequently have significant floodingproblems that are local in nature, but willalso be impacted upon by major flood eventson larger streams or lakes that are not withinthe urban zone.

A general rule is that the impacts of land-use change will be greater for smaller basinsthan for larger ones. Increases in flood peakand runoff volume in the range of 15-25%for medium-sized basins (>5000 squarekilometers) have been estimated intemperate climates. However, more detailedstudies are required before makingpredictions for specific basins and theirconditions. Scaling small basin results up tolarger basins and vice versa remains a majorscientific challenge.

38

2.5 Climate Variability and Change

There is growing concern about the impact ofchanging concentrations of greenhouse gaseson our current climate system and theramifications these changes might have onwater availability. It is believed that furtheralterations of atmospheric chemistry could leadto increased abnormalities in climaticparameters such as temperature, precipitationand evapotranspiration and might well lead tomore dramatic impacts on streamflow patternsand extreme conditions. Some analyses ofstreamflow over the last 30 to 60 years haveshown evidence of increasing and decreasingtrends in the low flows, with markedgeographic patterns to these trends. Thus far,there has been less evidence of trends in annualflood data for natural pristine basins. However,based on scenarios of projected futureatmospheric conditions, it is anticipated thatthere might be more pronounced alterations tothe streamflow regimes in various regions ofthe world. If these projections are correct,more severe or extreme conditions may prevail.

Climate impacts on extreme events

A number of studies on the potential impacts ofclimate change on flooding have been carried outas part of the work of the IntergovernmentalPanel on Climate Change (IPCC). Thesestudies indicate potential future increases in floodpeaks of approximately 15% in temperate zonesdue to increased storm activity and overallincreases in depth of precipitation.

At this point in time, it is not possible to predictpotential increases in flood peaks due to climatechange for specific basins with the degree ofcertainty necessary for their incorporation intothe design and planning process. However, thefreeboard on levees and other works canprobably accommodate the potentialmodifications in extremes due to climate changethrough modified operating procedures ofcontrol structures.

Sea level rise and storm surge

Coastal communities must also deal with theimplications of sea level rise, tsunamis, andocean storm surge in preparing for floodingevents.

Sea level rise due to climate change will resultin decreased river slopes in reaches abovewhere the river enters the ocean, therebyreducing the capacity of the channel to passflood flows. This increases the elevation offloods in coastal cities. While the rate of sea-level rise is slow, most protective works orflood plain delineation exercises are sufficientlylong term in scope to warrant consideration ofthe predicted rise.

Some studies have indicated that there ispotential for increased frequency of stormsurges, which result from high winds andincreased barometric pressure. Tsunamis canalso be devastating natural disasters and mustbe considered in a manner similar to flooding.Forecasting and emergency responses to theseevents must be based on the same principles ofacceptable risk and advance planning.

ENSO events

The El Niño Southern Oscillation (ENSO),related to changes in sea-surface temperaturesin the Pacific Ocean, can profoundly changethe weather patterns in Central and SouthAmerica. The number of hurricanes that canbe expected in a given season is also related.Climate predictions of above or below normalstorm activity during El Niño and La Niñaevents can assist with the regulation ofreservoirs and other water managementactivities that can reduce the magnitude ofpeak storm runoff. Flood forecasting andemergency response activities should also beperiodically tested to ensure they meetappropriate levels of readiness.

39


2.6 Development of Policies, Strategies and Plans

The development of policies, strategies andplans to combat the risks associated withnatural disasters should be based on acomprehensive risk assessment. Thisrequires an integrated approach whereby awide range of mitigation measures should beconsidered. For example, mitigationactivities such as hazardous land mapping(i.e., flood plain mapping plus landslide-and mudslide-prone areas) should bedesigned so that considerations of otherdisaster types lead to sounder overall land-use plans. In essence, there would be verylittle purpose in moving people and goodsfrom one risk zone to another, especially ifthe other hazard is equally or more apt tooccur under the prevailing conditions suchas torrential rain. Within this overallprocess, full consideration needs to be givento the social, environmental and economicimpacts of policy and programmedevelopment. This chapter providesguidance on aspects of flood hazards thatneed to be considered within the overallplanning process. The aspects containedherein are meant to complement othermaterials in this guide, such as thedevelopment of a flow forecasting andwarning system, which are important toolswithin the range of options to be considered.

Basin wide planning

Reduction of flood losses must beconsidered, using the basin as the basicplanning unit. It is absolutely essential tohave knowledge of water uses, diversions,storage, and management practices in allparts of the basin, as well as the antecedent,present, and forecasted meteorological andhydrological conditions.

Transboundary basins represent a specialchallenge in that international collaborationis required. In such cases consideration

should be given to expanding existingbilateral or regional arrangements forexchange of data and information and to thenegotiation of treaties or agreements.Agreements can also include the option ofprojects of mutual advantage funded by allthe countries involved, includingconstruction of flood storage or other floodpreventative measures at the mostadvantageous locations in the basin as awhole.

Multijurisdictional issues

Basin-wide planning for reduction of floodlosses can involve government at the local,provincial/state and national levels. As suchit is desirable to have the nationalgovernment develop strategies and policiesthat ensure a consistent framework whereverthey are applied. This can extend to matterssuch as installation and maintenance of datanetworks, design standards for protectiveworks, flood proofing standards, costsharing arrangements, and incentive andinsurance programmes.

In general the national level of governmentshould take the lead in bringing the partiestogether, but should delegate planning of thedetails and delivery of the emergencyresponse programmes to the local level.Generally the national and provincial/stategovernments will play some direct role inoperation of forecasting centres, and theywill need to provide for emergency responsethat exceeds the capability of the local level.There should also be a role of higher ordersof government in auditing enforcement ofpolicy measures by local levels.

Inter-agency collaboration

Reduction of flood losses will involve anumber of government agencies and often

40

the private sector if, for example, reservoirsare operated by energy utilities.Development of common objectives anddefinition of a clear role for each of theplayers can be a major challenge. From aland-use planning perspective, landdevelopers must also be directly involved inthe solutions.

Normally some form of inter-agency bodywill need to be established, and theleadership role assigned to the agency withthe greatest involvement or to a strongcentral agency. There is probably no idealmodel for such a structure, as circumstancesare quite different in every country.

An independent agency is an attractiveoption, but in general it is probably better totry and build on the strengths of existingagencies so that supportive resources can bemarshalled quickly in case of extreme events.However, within this diverse model, it isimperative that one agency be given theoverall lead, and that that agency be heldaccountable for the overall process.

International collaboration

There are a number of United Nationsspecialized agencies and programmes thatcan be of assistance to a country establishinga programme aimed at reducing the lossesthat result from flooding. Some of these aredescribed herein and could be contacted byinterested parties.

The UN Department of Economic andSocial Affairs (UNDESA) has been activelyinvolved in providing advice to governmentson water resource management duringextreme hydrological events in a wide rangeof environmental and climatic settings fromthe drought-prone upland plateaus of centralAfrica through large river basins and aquifersystems in Asia to vulnerable groundwaterlenses on Pacific atolls. If one principallesson is to be learnt, it is that managing

water resources under conditions of climaticvariability and extreme events involves nospecial approach; it is simply sound waterresource management. To this extent,climate change should involve relatively fewsurprises, and should not be an excuse forpoor management. It is only possible toundertake sound management practices,however, if the appropriate and accuratehydro-meteorological data are available toresource managers on a regular basis. Oneof the critical issues in this area is thebreakdown in hydro-meteorological datacollection systems and analysis. As fundingfor water resource organizations declines,monitoring networks and the capacity tocollect, store and analyze data break down.Ironically, it is only in times of drought orsevere flooding that the political will to fundthese activities is revived, by which time it isoften too late.

Water resources assessment is a core issuethat the UN system is addressing throughits technical cooperation activities and theWorld Water Assessment Programme.UNDESA's technical cooperation withdeveloping countries and economies intransition uses state of the art technologiesand software for the assessment of waterresources availability as a basis for short-term and long-term planning horizons.National capacity has been developed toperform and continue these assessments incountries such as Bahrain, Burkina Faso,Cape Verde, China, Jordan, Madagascar,Mali, Mauritania, Niger, Senegal, andYemen. This is of particular importance inwater-scarce countries, where water hasbecome a limiting factor for economic andsocial development.

UNDESA has been collaborating withgovernmental organizations to enhancenational capacity to address the problems ofwater quality assessment and overall watermanagement. Guidelines andrecommendations concerning water quality

41

Guidelines for Reducing Flood Lossesprotection and management are alsoprepared for national and regionalorganizations, dealing with monitoring andprotection of environment.

The United Nations DevelopmentProgramme (UNDP) has a programme forstrengthening national capacities related toflood mitigation, prevention andpreparedness in developing countries.UNDP works in flood reduction andrecovery through practical application at theregional and country levels. UNDP hasdevoted special attention to reducing socialand economic vulnerability and loss of lives,and to protecting livelihoods and broad-based development gains.

The World Meteorological Organization(WMO), a specialized agency of the UN,was established in 1950 to facilitateworldwide cooperation in meteorology,hydrology and climatology for the benefit ofhumanity. WMO promotes the followingtypes of activities: the establishment of thenetworks of stations for acquiringmeteorological, hydrological and relatedgeophysical observations and thestandardization of observationalmethodologies; establishment andmaintenance of systems for processing andexchanging data and information; activitiesin operational hydrology, such as floodforecast and warning systems; multi-agencyand interdisciplinary programmes on waterresources, climate change, natural disasters,and other environmental issues; andresearch and training.

The International Strategy for DisasterReduction (ISDR) was launched by theGeneral Assembly of the United Nations inJanuary 2000, to provide a globalframework for action with the objective ofreducing human, social, economic andenvironmental losses due to natural hazardsand related technological and environmentalphenomena. The ISDR aims at building

disaster-resilient communities by promotingawareness of the importance of disasterreduction as an integral component ofsustainable development. The GeneralAssembly established two mechanisms forthe implementation of the ISDR: the Inter-Agency Secretariat and the Inter-AgencyTask Force on Disaster Reduction(IATF/DR).

The ISDR Secretariat serves as a focal pointwithin the United Nations system for co-ordination of strategies and programmes fordisaster reduction and to ensure synergybetween disaster reduction activities andthose in the socio-economic andhumanitarian fields. The ISDR Secretariatalso serves as an international clearinghousefor the management and the disseminationof information, in particular on currentknowledge and status of disaster reductionthrough the publication of its Global Reviewof Disaster Reduction Initiatives. It developsactivities such as advocacy campaigns topromote wider understanding of naturalhazards, as well as risk assessment andmanagement to motivate a worldwidecommitment to disaster reduction. TheISDR Secretariat has a facilitating role,bringing agencies, organizations anddifferent disciplines together, and providinga common platform and understanding ofthe scope of disaster risk reduction. In thisregard, one main function of the Secretariatis to support the Inter-Agency Task Forcefor the development of policies on naturaldisaster.

In particular, the ISDR Secretariat supportsactivities, such as the development ofguidelines, related to reducing the risk fromwater-related hazards. This requires, on theone hand, support for the development ofcapacities to monitor the magnitude,duration, timing and location of hazards,such as floods and droughts, as well aslandslides, storms, earthquakes, and volcaniceruptions. All of these latter hazards also

42

have impacts on freshwater resources andinfrastructure. On the other hand, this alsorequires promoting the assessment andreduction of the vulnerability to suchextremes. This requires decision-making onissues such as development and planningcontrol, legislation and land-use,environmental management and financialtools (e.g., insurance).

The ISDR, with its focus on disaster andrisk reduction, draws its relevance fromprevious practices in the disastermanagement fields, where traditionally the

focus has been on preparedness forresponse. Political authorities, professionalsfrom many different fields, commercialinterests, public organizations, educationalinstitutions and local community leaders areincreasingly recognizing the essential publicvalue of sustained efforts to reduce thesocial, economic and environmental costs ofdisasters. There is now increased emphasisplaced on risk, and a growing acceptancethat disaster, development andenvironmental problems are inextricablylinked.

2.7 Emergency Preparedness and Response

The most critical element in the suite ofactivities associated with flood-loss reductionis emergency preparedness and responseactivity. The response to a natural disasterwarning must be immediate, comprehensive,and demonstrate very clear lines ofcommand. There must also be a mechanismin place to quickly draw upon externalresources available at higher levels ofgovernment, or even internationally, whenthe local level of response will not besufficient. Many countries have systems inplace where a provincial/state wide ornational disaster can be declared to bring inthe resources needed. The keys to effectiveemergency response are advance planning,ability to mobilize sufficient resourcesquickly, and periodic exercises to identifyweaknesses and problems.

Collaboration and coordination

Emergency planning and preparedness isfirst a local responsibility, but one thatrequires collaboration and coordination with

others in a growing circle of like-mindedand expert groups that can be drawn uponas events unfold. In particular, there mustbe strong and reliable communicationlinkages to storm warning and forecastcenters so that the emergency responseactions taken are appropriate to themagnitude of the probable event.

The network of linkages from the local levelupward must be established in advance and,more importantly, key players mustperiodically meet to exchange informationand become comfortable working together.Information sharing should be bi-directional, both upward and downward,between the levels of government. Practicedrills are important.

Emergency response must include inputfrom the community and political levels butcannot become a collective responsibility.There must be clear lines of authority, evenif the lead agency changes dependent on themagnitude of the event.

43

Guidelines for Reducing Flood LossesThe community and individuals must have agood understanding of what is expected ofthem. A good example would beevacuation. Information that definesevacuation routes, identifies emergencyshelters, and specifies actions to be takenbefore leaving, such as removing mobileequipment and removing personal goodsand furniture, must be available in advance.

Preparedness and response plans

Detailed response plans need to be preparedin advance and reviewed with all of the keyagencies and players. There is no one"common" response plan as the linkages willbe different in each case. The response to atoxic chemical spill is very different from theresponse to a major fire or flood.

Not only must the plan be in writing andavailable to those that will be responding,but also it must be continually reviewed andupdated. Some of the key pieces ofinformation are: which agency andindividuals have the specific responsibility;whom to contact for expert advice; andwhere to go for information on backupcommunication systems. This informationis constantly changing and needs to beverified periodically and tested in exercises.Multiple contact points need to beestablished as the emergency may occur on aweekend, holiday, or after regular businesshours.

Mechanisms for coordination must beincluded in the plan, including the structureof response committees, where they willmeet and sources of resource informationavailable to them. Often this takes the formof something equivalent to a "war room"where maps, plans, other material andsupport staff are available immediately.

Inventory of resources

A key component of any emergencypreparedness plan is an inventory ofresources that can be accessed. In the caseof flooding this could include items such asemergency vehicles, buses and trucks,earthmoving equipment, pumps, plastic,plywood, emergency generators, supplies ofgravel and sand, sandbags, and mobilecommunications equipment. The inventoryshould also include access to expertise suchas surveyors, levee or slope stability experts,forecasting specialists, the media andcommunity leaders.

Emergency shelters should be designated inadvance, their individual capacity definedand plans made for obtaining sufficientsupplies of water, food, medicine andmedical/social assistance.

If local resources are not sufficient, then theavailability circle must be expanded toinclude adjacent communities, theprovincial/state and national governmentlevels.

Triggering emergency action

Advance warning is the key to effectiveresponse. It is possible to set up a series ofwarnings in advance of an actual extremestorm event that can be used as alerts. Thiscould start with long-term climatologicforecasts or more immediate hurricaneforecasts that identify potential danger. Forspecific basins an alert could be issued basedon antecedent precipitation and rainfallintensity data in advance of an actual floodforecast. A more detailed forecast wouldthen be issued when all of the data andinformation required to make a floodforecast became available.

44

The emergency response to such alerts isvery site-specific and should be included inthe plan. If, for example, emergency actionssuch as temporary levees are necessary, thenthe work could begin based on an alertrather than the specific forecast. The samemay hold for emergency evacuation.

The response to an extreme flood forecastshould be immediate, and with no uncertaintyas to what actions and activities should betaken. The public expects governments to actquickly and in a professional manner undersuch circumstances. Community leadersshould be visible, informed and active rightfrom the start.

Training and response exercises

Emergency response teams need to be welltrained in advance and their skills constantlyupgraded. Once the disaster strikes, it is toolate to train or try to find missing expertise.Trained staff should know theirresponsibilities, have immediate access toresponse plans and other criticalinformation, and already have built aworking relationship with colleagues inother organizations.

The only meaningful way to test responseplans is to carry out periodic emergencyexercises. These exercises are meant tosimulate real emergency situations and testall aspects of the plan. Costs are significant,but have real payback in an actualemergency. Often critical gaps are identifiedand appropriate backup strategies developedas part of the exercise.

Advance preparation

Assuming that there is advance warning of amajor storm event, a number of steps can be

taken to increase readiness. Such stepsinclude: construction of temporary floodprotection works; placing emergency responseteams on high alert; distribution of criticalmaterials such as stockpiled sandbags totargeted locations; and preparation ofemergency shelters and hospitals prepared foroccupation.

The population at risk can be informed ofwhat is expected of them in the actuality of anextreme event. As the event becomes morecertain, actions such as evacuation of people,goods and machinery can begin. Even if theevent is not as extreme as predicted, thesepreparations help test emergency responseplans and inform the public as to the nature ofnatural hazards.

Media and public information sessions helpset the stage as well. The media are keyplayers in the link between public officials andthe public. It helps if they are familiar withthe terminology used in warnings andforecasts and know whom to contact for moredetailed information during an actual floodevent.

After the flood event

The emergency response does not end withthe event, but continues through cleanup andresettlement stages. People will want to knowwhat assistance will be made available, who isresponsible, and how to go about seeking thatassistance.

Senior levels of government should developclearly defined response policies andprogrammes in advance. In the absence ofsuch policies, the response is often ad hoc,politically and emotionally motivated, and setsprecedents that are not wise in the longer run.Often the response is incomplete in that the

45

Guidelines for Reducing Flood Lossesobvious and immediate requirements areaddressed, but fundamental changes inthinking and sustainable strategies areignored.

After a major flood it is beneficial to conductan assessment of the causes and effects of theflood and to make recommendations thatwould improve preparedness for the nextevent and reduce future flood losses. Such anassessment can also lead to improvements inflood plain management policies.

The long-term economic and socialimplications of flooding become evident in thepost-disaster period. Governments need todemonstrate leadership and sometimes takebold steps to restore employment, addresssocial issues and move the economy in a newdirection. In that sense, natural disasters canbe a positive motivator for change.

47

Integrated Flood Forecasting,Warning and Response System

3

48

3.1 Defining an Integrated System

Establishing a viable flood forecasting andwarning system for communities at riskrequires the combination of data, forecasttools, and trained forecasters. A flood-forecast system must provide sufficient leadtime for communities to respond.Increasing lead time increases the potentialto lower the level of damages and loss of life.Forecasts must be sufficiently accurate topromote confidence so that communities willrespond when warned. If forecasts areinaccurate, then credibility of theprogramme will be questioned and noresponse actions will occur.

Flood-warning systems must be reliable anddesigned to operate during the most severefloods. The greatest benefits for an effectiveflood-warning programme occur whenflooding is severe, widespread, and/orsudden, and when communities andorganizations are prepared to mitigateimpacts.

The implementation of an end-to-end floodforecast, warning and response systemconsists of many components. Thesecomponents must be linked for successfuloperation. The interaction of components ofthe integrated flood forecast system orprogramme could be represented as a chain

composed of many links. Each link must bepresent and functional if benefits are to beachieved. Figure 12 shows a schematicrepresentation of the system as links in achain.

The essential links or components of theintegrated flood forecasting, warning andresponse system consist of a Data Source,Communications, Forecasts, DecisionSupport, Notification (often referred to asdissemination), Coordination, and Actions(or responses). A flood forecast and warningprogramme should be designed to mitigatefloods, and, as such, it is an asset to overallwater management. To achieve this, it isimportant that all of the components of thesystem be functional. If any component isdysfunctional, then this weak link couldbreak the chain, resulting in an ineffectivewarning and response process. For example,if critical rainfall or streamflow data areunavailable or if the data are not relayed to aforecast centre for use in forecasting, thenthe critical lead time required to makedecisions, coordinate activities, warncitizens, and take actions is not possible. Ifa perfect flood forecast is generated but doesnot reach the population at risk, then thewarning system is useless. Equally, shouldthe population at risk receive the warning

Figure 12Integrated flood forecasting, warning and response system within IWRM

GIS T oo lsMa th ema tic a l Mode ls

Data Communication Forecast DecisionSupport Notification Coordination Actions

Sense WaterAvailability

Get Datawhere

Needed

FutureWater

Availability

Water Mgmt.&

Flood ControlDecisions

AppropriateIndividuals& Groups

Tasks fromResponse

PlansOrganisationsCivil society

RelocationSand baggingOther responses

Flood and Water Resources Management: a Critical Chain of Events and Actions

49

Guidelines for Reducing Flood Lossesbut not know what actions should be taken,then the system again would not haveaccomplished its purpose.

In the overall design of the integratedsystem, there are many factors that shouldbe considered. The remainder of thischapter reviews some of these factors.

Basin characteristics

The physical characteristics of the basin,such as surface area, topography, geology,and land surface cover, will help todetermine the nature of potential floodingand the basin's susceptibility to relatedhazards such as landslides and mudflows.

The hydrological response of the basin canbe impacted upon by changes in land useassociated with urbanization, forestry,agriculture, drainage, or channelmodifications. A record of such changesover time is useful in establishing thedynamic relationship between rainfall andrunoff. The following also contribute to anunderstanding of flood hazards: records ofclimate norms and trends for parameters,such as precipitation and evapotranspiration;and information on the usual effects ofENSO events and extreme events, fromsynoptic to mesoscale.

Population centres often are adjacent torivers, and flood plains can be richagricultural resources. Identification ofpopulations and economic activities at riskshould be carried out early in the process, asthis will shape the eventual forecast output.

Flood history

Flood history, also known as paleohydrology,can be inferred from study of sedimentdeposits, tree ring analysis, and examinationof a number of other biological indicators.Such analyses will not lead to adetermination of flood volumes, but may

help put a recent flood into context. Often,such records are of value in defining theflood history in a river basin, particularlywhen combined with stream gauge recordsthat exist for contemporary periods. Othermore recent historical information can bedrawn from newspapers, journals and oralhistories. Usually there is a perception levelassociated with flooding at a given location;large events are noted, smaller events arenot.

The flood history will identify the portionsof a basin subject to flooding, whetherflooding is urban or rural or both, seasonalcharacteristics of flooding, and the feasiblewarning time. The type of flooding andassociated hazards may be significantlydifferent on tributaries compared to themain stem of the river. Knowledge of thefactors contributing to or causing theflooding such as meteorological andantecedent conditions should be establishedfor each flood event.

Lake flooding as well as flooding fromocean surge and tsunamis may poseproblems quite different from river flooding.These guidelines are oriented to riverflooding, but many principles containedherein are also applicable to varying degreesto other water-related disasters.

Environmental factors

Floods can induce major changes in rivermorphology, mobilize nutrients andcontaminants in the soil, release othercontaminants from storage depots, anddischarge effluents to the river.Deforestation, fires and erosion of materialscombined with saturated soils can lead tolandslides, mudflows and other threats tohuman settlements. Sometimes floods areaccompanied by strong winds that also canpose threats to human life and property. Ananalysis of potential environmental risks willhelp determine flood forecasting and

warning needs. This can help to shapefuture approaches to flood plainmanagement and regulation, and can assistin the design and establishment of responseactions.

Economic factors

A flood forecasting, warning and responsesystem comprises an important element ofintegrated water resources management.The benefits of river forecasts for powergeneration, navigation or irrigatedagriculture make implementation of such asystem more cost effective and sustainable.Even then, maintaining a system in a state ofreadiness between floods may be difficult.

An examination of past damages and thepotential for future damages will helpdetermine priority areas for floodforecasting, warning and response.Rigorous analysis would call for statisticalanalysis of flood peaks and the calculation ofthe present value of costs and benefits offlood forecasting and warning. In mostcases, however, the benefits of floodforecasting, warning and response arevirtually self-evident. The real questions arethe affordability of various options and thedesire of society to invoke a more pro-activestance to reducing flood losses.

Communities at risk

While flood losses in rural districts can bedevastating to those areas, the mostsignificant losses are usually in urbancommunities because of the concentration ofpeople and related socio-economicinvestments. The basin characteristics andflood history of individual communities,combined with damage estimates fromprevious floods, will give some indication ofthe type of flood forecasting and warningsystem that may be most suitable foreffective warnings. Once the system isdefined, consideration should be given as tohow it could benefit rural areas as well.

System identification

Depending on the nature of the basin andthe type of event causing the flooding,potential warning times could vary fromhours to several days to weeks.Communities subject to flash floodingrequire warnings of meteorologicalconditions that, when combined withantecedent basin conditions, could lead toflooding. This represents a special case offlood forecasting and warning. Thechallenge in such cases is rapid depiction ofcritical flood thresholds and theirsubsequent communication and emergencyresponse. An analysis of historical rainfallrecords, including storm transposition andthe resulting streamflow would help toidentify areas of concern.

When warning times are longer than a fewhours, full-fledged forecast systems shouldbe contemplated. The degree of desiredautomation and sophistication must beconsidered in light of current needs andcapabilities. Automation needs can beconsidered in sub-systems: data acquisitionand transmission; data processing; forecast

Pho

to: J

. Lau

rie,

Las

Veg

as R

eview

Jou

rnal

Las Vegas, July 1999, flash flood meets desert

50

Guidelines for Reducing Flood Lossespreparation; and forecast distribution.Different levels of automation may berequired as the overall system develops andexpands, and as financial resources becomeavailable. Systems may vary from thoseusing largely manual observations, graphsand tables to highly automated multi-modelsystems running on computer workstations.

Benefit-Cost analysis

An analysis of the cost of floods and thepotential benefits may help determine thetype of forecast and warning system andresponse mechanisms that would be mostcost effective. Costs resulting from floodingcan be estimated for various magnitudes ofevents for various centres. Damage statisticsfrom previous floods are also valuable inestablishing the costs associated with suchevents. Judgement is needed to estimate thebenefit of flood forecasting and warning inreducing damages and loss of life.Governments and financial institutionsrequire such information on costs andbenefits to help understand whereexpenditures will reap the largest rewards.Studies and analyses have shown thatdamage reduction due to forecastimprovements can range from a fewpercentage points to as much as 35% ofaverage annual flood damages.

A standard set of flood damage categoriesrelevant to the basin should be developed.When loss of life is a threat, this tooshould be identified, even though it isdifficult or impossible to quantify ineconomic terms. Other damage categoriescould include residential buildings;commercial, institutional and industrialbuildings; agricultural lands; andinfrastructure. Additional costs includetemporary relocation and flood-fightingcosts. Floods can have an effect on thepopulation and economy of an entirecountry, and business losses should also beincluded in the analysis. Developingstandard damage categories allows

damages to be more accurately estimatedfor various levels of flooding.

A rigorous cost-benefit analysis wouldrequire determining a flood frequencydistribution so that the present value offuture benefits can be determined. In theabsence of sufficient data or analysis, a morerudimentary presentation of costs andbenefits may be sufficient to determine thesize of the investment that is justified forflood forecasting, warning and response.

Evaluating existing capabilities

Most countries have basic networks ofmeteorological and hydrometric stations thatare necessary for flood forecasting andwarning. It is likely that the operators of theexisting networks may be in many differentagencies. In many cases, the networks maynot have been designed to acquire dataduring extreme events, or they may notprovide data in real-time or to commonstandards. Also, networks may not providedata for key urban centres where forecastsare required or for areas where the majorinputs to the flooding are occurring.Identifying the existing network, itsoperators, and the existing approaches andcapabilities are necessary steps in theevolution of a flood forecast system.

Another important element is anexamination of existing communicationscapability. Given that important data areavailable at a remote site, how can these databe reliably transmitted to a flood-forecastingcentre? Will telephone or radio links -manual or automated - function during aflood emergency?

Some agencies may have developedhydrological mathematical rainfall-runoffmodels and flow routing models for theirown purposes. These models may be usefulas flood forecasting models. An inventoryof existing models will also help definecurrent capability within individual agencies.

51

52

Identification of key users andcollaborators

Establishment of a successful floodforecasting, warning and response systemdepends on a thorough analysis of existingcapabilities, identification of key users forthe system, and a good understanding of theinteragency arrangements needed in aneffective system. Considering these factorswill lead to forecasts that meet user needsand that are more likely to be acted uponduring an emergency. The ultimate goal ofsuch a system is to ensure the safety andsecurity of the public and to protect propertyand the environment. To achieve this result,however, means that the public must receiveand understand forecasts, and the myriad ofagencies having responsibility for emergencyaction and response also must receive theforecasts, have response strategies in place,and act upon the forecasts accordingly.

Key users typically include: civil agencies atthe national, provincial/state, and local level;military organizations; corporations,especially those which operate structures;volunteer emergency response organizations;and the media. A user analysis, and close

ties and interaction with these groups shouldbe considered to help establish overall floodforecast needs and response measures. Therole of the media in informing the publiccannot be underestimated. It is critical thatthe media receive timely and authoritativeforecasts and warnings. Mediacommunications should encourage theappropriate public response and should notlead to counterproductive speculation.

Many of the world's river basins have atransboundary component. In some casestransboundary basins are covered by treaty,international agreements, or otherinstitutional arrangements. Sucharrangements may or may not include riveror flood forecasting. Shared basins imply ashared responsibility; an analysis of userneeds should include users in othercountries.

Often the mandate and capabilities ofgovernmental organizations are not entirelyclear. An institutional analysis of eachagency's mandate, needs, capabilities andlegal responsibility during a floodemergency will help shape an emergencypreparedness and response plan. Overall,one agency should be assigned the leadresponsibility (and accountability) for anend-to-end system, with the system itselfpotentially being operated by a number oforganizations.

In the evaluation of the existing system,agencies that operate data collectionnetworks or models, or that can contributeto a forecast system in other ways, will havebeen identified. In some cases the potentialrole of a specific agency in a flood forecastsystem may be relatively clear, while in othercases that role may have to be identified andnegotiated.P

hoto

: V. T

hanh

, IF

RC

Vietnam Mekong Delta floods, 2000Roads and infrastructures were badly damaged by the floods in An Giangprovince, making relief distributions a challenge.

53

Guidelines for Reducing Flood LossesA fundamental question is that of hydrologicaland meteorological coordination. In manycountries one or more agencies operatemeteorological forecast and climate networks,while hydrological networks may be theresponsibility of entirely different agencies ordepartments. Coordination among thesebodies is essential because development of aflood forecasting system may require theaddition of new sensors or telemetry equipmentfunded by one agency being installed at a siteoperated by another one. A successful forecastsystem will depend upon cooperation amongmeteorological and hydrological agencies andcould involve financial transactions amongthem.

Similarly there may be a number of agencieswith responsibility for operation of structuresfor water management and flood control.These could include hydroelectric generationfacilities, irrigation headworks, water supplyreservoirs, and so forth. Individual structuresmay have an established operating plan, but anintegrated plan for operations during extremeevents is needed to provide optimal floodcontrol benefits and to avoid structural failure.Interagency co-ordination and cooperation isrequired to ensure the integrity of the entirewater management system during extremeevents. A flood forecasting and warningsystem provides the information necessary toimprove decision support for the operation ofstructures.

Some agencies may have arrangements fortechnical support or financial assistance withinternational organizations or with othercountries. These may prove beneficial indeveloping or improving a forecast systemthrough training and in general strengtheningof much needed organizational infrastructure.

A logical agency to lead a country'sflood forecasting and warning effort mayemerge from this analysis. Theidentified agency will require technicalsupport and leadership from severalagencies. More importantly, there is aneed for long-term political support forthe endeavour. Flood forecasting andwarning will have to compete with othernational priorities, and resources andfinancial support can atrophy,particularly in the absence of flooding.

There is a need to establish a flood-forecasting centre having a legalmandate to issue authoritative forecastsand warnings on the river basin or at theprovincial/state or national level. Theseforecasts must be understood byagencies having the responsibility foremergency response and by the generalpublic. Such agencies, civil organizationsand the general public must be aware oftheir roles, have response mechanisms inplace, and know what actions to takeunder various circumstances.

Determination of specificforecast system requirements

Analysis of the basin characteristics, floodhistory, flood damages, and the existingdatabases will give some indication of thetype of forecast system that is achievableand affordable. It is likely that the systemwill be based on enhancing existingnetworks and agency capabilities.Establishing a new system implies phaseddevelopment from the existing system tothe new one. Establishing a long-termplan with specific milestones is critical tofuture success.

54

3.2 The Hydrometeorological Network for Forecasting

The hydrometeorological network is the keyrequirement for most flood forecasting. Inparticular, precipitation and streamflow dataare needed. If snowmelt is a factor inflooding, then measurements of snow waterequivalent, extent of snow cover, and airtemperature are also important. In manycases agencies other than the forecast agencyhave useful data. Rather than duplicatenetworks, it is preferable to developcooperative arrangements. In some respects,it is preferable that the network serves manypurposes as this may result in its broaderfinancial support.

In most cases data network operationalperformance is the weakest link within theintegrated system. Operational datanetworks must be examined. Are the rainfalland stream gauge (hydrometric) datanetworks satisfactory in sampling rainfall(intensity and spatial distribution) andstreamflow response for the river basin? Arestream gauges operating properly, and arethey providing accurate conditions of waterlevel and streamflow? Are datacommunicated reliably between the gaugesites and the forecast centre? How often areobservations taken, and how long does ittake for observations to be transmitted to theforecast centre? Are data available to userswho need the information for decisionmaking? Are the data archived for futureuse? Are the data collected to knownstandards, is the equipment properlymaintained and calibrated, and are the dataquality controlled?

Network design

It is not possible to manage water or forecastfloods without data. Various types andsources of data are needed to monitor the

environment, conduct a water balance orprovide input to hydrological models thatestimate streamflow from rainfall. Operatinga real-time hydrometeorological network isessential, as data provide the foundation forestablishing the potential for flooding. In-situ observations of meteorological andhydrological parameters are required asinputs to the hydrological prediction system.

An analysis of the existing network should beundertaken. Tables and maps should beavailable providing details on monitoringlocations, parameters, sensors, recorders,telemetry equipment and other related data.In addition, monitoring sites in adjacentbasins should be inventoried. In low reliefbasins, data from those sites could be veryuseful. Analysis should be performed toidentify sub-basins that are hydrologically ormeteorologically similar.

Based on forecast needs, the adequacy ofnetworks can be determined and requiredmodifications can be noted. These couldinclude new stream gauges, rain gauges andpossibly other sensors in the headwaters, oradditional telemetry equipment. In somecases, network sites may not be well suitedfor obtaining flow measurements or otherdata under extreme conditions. Costlystructural alterations may be needed.Interagency agreements may be needed formaintenance and operation of the network.

A key variable to be established is the timestep needed to adequately forecast a flood fora given location. If the time step is, say, sixhours then data must be collected every threehours or even more frequently. In manycases, supplementing a manual observernetwork with some automated gauges mayprovide an adequate operational network.

55

Guidelines for Reducing Flood LossesData acquisition

Generally the design and operation of datanetworks have a large influence on forecastsystem accuracy and in the ability of thesystem to provide the necessary lead-time toissue warnings so that response actions canbe taken. It should be underscored that thedesign of reliable real-time operationalobserving networks is critical to the successof a forecast, warning and responseprogramme. In order to be effective duringextreme conditions, sensor installations mayhave to be "hardened" to withstand extremesin wind, rain or flood stage.

The advent of remotely sensed data hassignificantly improved the ability ofoperational hydrology to infer watershedconditions in data-sparse regions. Theapplication of radar-derived precipitationestimates serves as the principle tool inforecasting floods and flash floods in manycountries. The use of geostationary andpolar orbiting satellites to derive largevolumes of meteorological and hydrologicalproducts is rapidly advancing. Remotelysensed data can now be used to provideestimates of precipitation, snowpack extent,vegetation type, land use,evapotranspiration, soil moisture and floodinundation. This information is becomingincreasingly useful in data-sparse regions ofthe world where water availability and floodforecasts are needed.

Many countries use the GlobalTelecommunications System (GTS) of theWorld Meteorological Organization(WMO) for the transfer of real-timemeteorological data. More recently, somehydrological data from a number of projectswere added to the system. Even with theseadvances in remotely sensed data and theiruse, inadequacy of data remains the biggestweakness in establishing a viable floodforecast programme for a river basin or for acountry.

Data communications

For data to be useful to the forecast centre,point data observed at remote locations mustbe converted to digital formats. This mayrequire changing the sensor itself or simplyadding another component to an existingsystem. The format for the digital datamust be specified. Remotely sensed imagesused in forecasts are usually already in aspecified digital format. If the sensor outputis film, arrangements must be made to makethe conversion to a specified digital formatwithin the required time.

Once data have been observed or collectedat sites throughout the river basin orcountry, the data must be transmitted tolocations where they can be stored, accessed,and used. The value of data increases withthe speed of transmission and processing,from their initial observation to where theyare used. Meteorological and hydrologicaldata are needed almost instantaneously sothat the hydrological forecast system canproduce up-to-date and reliable forecasts.More importantly, this allows the system toprovide the critical warning times needed forusers to take actions. This is especially truefor issuing warnings of flash flood eventsand of potentially hazardous mudslideconditions.

There are many types of communicationtechnologies that can be applied to transmitdata from sites in remote locations to theforecast centres. The most common form ofdata communication is by telephone.However, telephone lines frequently failduring severe flood events. More reliablebut potentially more expensive forms of datacommunications are satellite, line of siteradio, cellular radio and meteor bursts.These also have their strengths andweaknesses. An evaluation should beperformed to establish the most suitable,reliable and cost-effective form ofcommunication for the local situation.

Data may be transmitted by dedicated satellitelinks, radio links, by commercial telephonelinks or other shared services. In some casesthe data link could simply be a voicetelephone communication. The forecastcentre may be required to poll sitesindividually, interrogate a third-party system,or use the Internet to obtain data. Datatransmission links must be identified, andtheir reliability and speed should bedetermined. If image products are to play arole in the real time forecasts, bandwidth ofthe transmission system and speed of theprocessing system should be examined.

In many cases, national, provincial/state, localgovernments and the private sector operatereal-time data networks to support theirindividual needs. In most cases, these data arenot shared, and each organization is limited toits own data. Coordination and data sharingcan significantly increase the amount of dataavailable for all organizations. Theseadditional data, possibly complemented withnew sites, will help increase forecast accuracyat the least cost.

Network operation

Often times the current operator of a site willnot have had a need for, or experience with, realtime data acquisition. Intensive staff trainingmay be required to ensure that data areavailable when needed and are of a suitablequality.

Long-term maintenance is a major requirementin operational forecasting. The forecastnetwork may be in operation only seasonally orless frequently. Keeping the network in a stateof readiness though necessitates major changesin operating philosophy. The development ofwater management operational forecasts by theforecast centre, as well as flood forecasts,enhances the usefulness of the data network andcommunications systems, as well as maintaininga state of readiness.

Funding of alterations to existing networks andfor future maintenance presents a majorchallenge. Negotiations among operating orfunding agencies may require abandoningentrenched positions if success is to be achieved.

3.3 Meteorological Support

Given the importance of meteorological dataand forecasts to the production of floodforecasts, it is very important that there beclose collaboration between nationalmeteorological and hydrological services.This collaboration could take several formsand should focus on increasing the accuracyand utility of knowledge of existingconditions and forecasted states. Twoimportant products are optimal quantitativeprecipitation estimates - where, when andhow much precipitation has actually fallen -and quantitative precipitation forecasts -where, when, and how much precipitationwill actually fall. Other parameters ofinterest include wind speed and direction,surface temperature, and relative humidity.

Quantitative Precipitation Estimation(QPE)

Optimal estimates of existing precipitationconditions provide the hydrologist with themost accurate estimates of what are termed"antecedent conditions". These are extremelyimportant for hydrological process modelling.Much work has been done to increase theaccuracy of the estimates through increasingthe density of in-situ stations, implementingground-based surface radar, in processing ofsatellite based data, and in merging varioussources of data.

56

57

Guidelines for Reducing Flood LossesQuantitative PrecipitationForecasting (QPF)

The ultimate goal of flood forecasting is toprovide accurate forecasts of hydrologicalconditions. Currently, deterministicquantitative precipitation forecasts and otherforecasted meteorological parameters can beapplied as input to hydrological models inorder to derive hydrological forecasts usingnumerical modelling methods.

It is typical that the hydrological forecasterreceives single "best effort" meteorologicalproducts such as QPF, wind speeds anddirection, temperature, and pressure. Theseproducts are based on numerical weatherprediction model output and are modifiedusing expert forecaster judgement. Forecastmodels are typically run once or twice dailydepending on the operational practices ofthe national meteorological service. Theuseful forecast horizon of such products istypically about five days, with accuracydecreasing rapidly towards that of long-termclimatology. The usefulness of QPFproducts derived from such modelling isusually constrained to one to two days dueto poor performance beyond these limits.

When very short forecast horizons on theorder of six hours or less could provebeneficial, extrapolative and trend-basedmeteorological techniques are used. Theuse of these techniques is referred to as"nowcasting", resulting in short-range QPF.These shorter time horizons associated withnowcasting are particularly useful for flash-flood forecasting. Beyond this horizon,numerical weather prediction modelscombined with expert judgement providemore accurate estimates of futuremeteorological conditions such as QPF.

Work is currently proceeding on thecoupling of mesoscale numerical weather

prediction models with high-resolutionhydrological process models. Questions stillexist on how to best incorporate expertjudgement into this process in order toprovide a single "best effort" estimate of futurehydrological conditions.

One forecast methodology that can be appliedto both meteorological and hydrologicalforecasting is the "Ensemble Technique",wherein multiple forecast scenarios aregenerated by the execution of several modelruns, each with slightly varied initial states.The magnitude and degree of the uncertaintyassociated with the forecast ensemble provide aprobabilistic view of the potential futuremeteorological and hydrological states.Although more study and further developmentare needed before this becomes more broadlyused in operational practice, the techniqueholds much promise.

Once a flood forecasting centre has been inoperation for a period of time and closecollaboration exists with meteorologicalcounterparts, weaknesses in bothmeteorological and hydrological forecastproducts may become evident. Sometimes theweaknesses can be overcome by improving thedatabase used for the forecast. In other cases,there will be a need to improve understandingof the underlying hydrological processesinvolved in the production of hydrologicalforecasts.

Other parameters of interest

Estimation of other parameters is importantfor flood forecasting and for assessingantecedent basin conditions. These includeantecedent temperature, humidity, andevapotranspiration, all of which are veryimportant in assessing soil moisture conditionsand water deficits prior to the onset ofprecipitation.

58

3.4 The Forecast Centre

The flood forecast centre must be identifiableto agencies and to the public as theauthoritative source of flood forecasts andwarnings. The forecasts produced by thecentre must be to the highest achievabletechnical standard and be released to thepublic unfiltered by agency or politicalinterests. The long-term stability of the centreis dependent on the credibility and utility of itsforecasts.

Administratively the centre can be part of oneagency or it could be a new entity supportedby several agencies. The forecast centre couldbe self-contained or, more likely, will dependon other agencies for support.

Establishment of the centre

Analysis of existing conditions and needs willdetermine whether a forecast centre will beestablished by strengthening an existingfacility or by creating a completely newenterprise. The decision should be based onpolitical, administrative and technicalleadership of candidate agencies, as well as theability of the selected agency to work withothers.

A project initiation team drawn from severalnational agencies or consultants, with supportfrom international organizations and workingto agreed-upon terms of reference, couldexamine the issues identified in theseGuidelines and make recommendationsconcerning the development of a ForecastCentre. Their report should identify technicalissues, personnel needed, administrative issues,costs, and timelines.

Interagency agreements will be needed forprovision of data, operation of structures,weather forecasts, technical and administrativesupport, and other tasks. Depending on thebasin, it is possible that such agreements

might already exist. They may include clearlyarticulated roles and responsibilities, clearspecifications of work, performance measures,and provisions for financial arrangements.International agreements for provision of data,use of satellite technology, and other supportactivities may also be required.

The Centre needs financing over both theshort and longer term. Short-term financingwill be capital intensive as funding may benecessary for network improvements,construction, the acquisition of computers andsoftware, and many other items. These couldbest be funded by special nationalappropriations or international support.There may also be a local market forspecialized forecast products, which could bepaid for by users.

Long-term financing will be needed to operatethe Centre, pay staff, upgrade computersystems, and make improvements in theforecast methodologies. This operation willrequire on-going national support even wherespecific improvements are fundedinternationally. If the mandate of the Centrewere expanded to include river forecasts foroperational water management purposes,financial support could be made available fromagencies using the river forecasts. Thepossibilities include revenue from sale of waterlicenses, other water use charges, or feesassessed to discourage development within theflood plain.

To operate effectively the Centre will need keypersonnel. Aside from technical skills, theCentre will need people capable of workingcollaboratively with other agencies and whocan communicate effectively. A significanttraining programme will be needed at theonset of the Centre, and the costs of on-goingtraining should be built into the budget. Inthe early stages, forecast procedures may have

59

Guidelines for Reducing Flood Lossesto be tailored to the ability of existing staff, anda training and development plan should beestablished to upgrade skills and techniques toimprove the accuracy and utility of the forecast.

There will be an early need to gather basicdata, calibrate and verify models, and establishworking arrangements with other agencies.Visiting experts, or placing key staff in otherForecast Centres for training, could aid thisprocess.

One approach in the early stages ofdevelopment would be to concentrate efforts ona key basin or one of its sub-basins. Such apilot project could help verify the suitability ofmodels selected and the capabilities of staff.This would give funding agencies a level ofcomfort. In the very earliest stages ofdevelopment, the Centre could simply analyzeweather forecasts and provide warnings ofpotential high flow conditions.

Data processing

Although data may have been pre-processedelsewhere, the Forecast Centre will require in-house data processing capability. Althoughsome work could be done manually, computersystems should have uninterruptible powersupplies. At the very least, emergency powersystems should be available.

If Geographic Information Systems and imageproducts are expected to be used for real-timeforecasts, computer memory and speed mustbe taken into account. Overall computingsystem architecture and design should beplanned for as part of the future developmentof the Centre.

Data processing needs will also depend uponthe selected forecast models and their dataprocessing requirements. In the absence ofother requirements, data should be digitallyavailable and easily converted to formats usedby commercially-available spreadsheetprogrammes.

Arrangements must also be made toelectronically archive data so that they areavailable for use in subsequent years. Somedata will have to be brought forwardfrequently for use, while other data will only beused on occasion.

Forecast Centre operation

It is necessary to establish basic operatingprocedures and assign staff responsibilitiesearly in the operation of the Centre. Part ofthis is the assignment of responsibilities for on-going maintenance of systems.

Capable staff are the key to producing goodforecasts and maintaining the Centre'scredibility. Capable staff will also be attractedto positions elsewhere so some staff turnovercan be expected. A systematic plan for stafftraining and development and the assignmentof challenging work will help reduce turnoverrates. Some contingency planning will beneeded to ensure that the Centre will continueto operate when key staff members leave.Efforts should be made to develop anoperations manual in order to reduce theCentre's vulnerability to loss of staff or otherunanticipated events. The manual shouldcover all aspects of the Centre's operation andmaintenance, and it should include lists of keycontacts beyond the Centre.

Once the Centre has completed its firstsignificant flood forecast season, an end-to-endreview of all aspects of the forecast should beconducted to identify what went well andwhere improvement might be necessary. Thereview should include interviews with personsfrom other agencies and forecast users. Theresults of such a review should be used tomodify procedures. Periodic audits of forecastprocedures and Centre operations should becarried out, perhaps involving staff from otherForecast Centres.

60

Forecast models

There are a large number of public domainand proprietary models available for use inflood forecasting. Sometimes the model canbe simply a statistical rainfall-runoff relationwith a routing equation, while other modelscan be much more complex. Hydrologicalmodels can be classified as lumped, semi-distributed or distributed, and as being singleevent or continuous. Probabilistic models thattake data uncertainties into account are alsoavailable. Model selection will depend onavailable data, basin characteristics, and theneeds of the local user community.

A lumped model treats the watershed as asingle unit for inputting data and calculatingrunoff. The calculations are statistically basedand relate to the underlying hydrologicalprocesses as a spatially averaged process.Models based on scaling unit hydrographswould fall into this category. Some lumpedmodels allow the watershed to be subdividedor for some parameters to be physicallyestimated and modelled. When subdivisionsof a basin are combined to produce a forecast,this modelling approach is termed semi-distributed. Depending on forecast needs andthe characteristics of the watershed, a lumpedmodel may be all that is required.

A distributed model simulates the keyhydrological processes that occur in awatershed using distributed data inputs andprocesses. For forecasting purposes thesecommonly include precipitation, interception,infiltration, interflow, and baseflow. Overlandflow and channel routing may be incorporatedinto the model or calculated in a hydraulicmodel. Distributed models require muchmore data and knowledge of watershedprocesses than lumped models. When themodel is first established, precipitation andland cover characteristics may be the onlydistributed features.

Hydraulic models used in channel routingcalculate the travel time of the flood wave and

its attenuation. These models use thestandard equations of unsteady, non-uniformflow with various simplifications dependingon the channel characteristics, available dataand accuracy requirements. Storage-flowrelations are often incorporated intohydrological models. One-dimensionalunsteady flow hydraulic models can be usedto route flows through multiple channels orin situations where overland flow is a seriousconcern.

Probabilistic forecasts are typically derivedusing hydrological process models whereinstatistical distributions are used to describethe uncertainty of input data and basinconditions such as precipitation data, soilmoisture and snow pack conditions. A largenumber of model projections are producedthat can be statistically analyzed to allow fora better understanding of the uncertainty ofthe forecasted future water conditions. Thisapproach is rapidly gaining popularity, as itprovides the decision-maker with theprobability of an extreme event to occur, notjust that it might occur.

Simplified probabilistic methodologies thatprovide a range of possible forecasts haveexisted for some time. This is achieved bythe forecaster making assumptionsconcerning future precipitation to determinerunoff under normal, lower, or upper decileconditions. More modern approaches,which tend to be in the pilot testing stage,attempt to better quantify the uncertaintyassociated with the forecasted meteorologicalconditions and to directly link thisuncertainty to the uncertainty of the floodestimate.

Sophistication of hydrologicalforecasting

Essentially, the prevailing geomorphologicalconditions of the river basin and theinteraction of communities at risk with theriver system dictate the level of sophisticationof the modelling solution. The performance

Guidelines for Reducing Flood Lossesof existing models or forecast procedures shouldbe evaluated. Whether the forecast processinvolves use of simple graphs or tables or arobust integrated modelling system, evaluationof forecast accuracy versus lead-time should bedetermined. Does the system perform well whenadequate data are available? Are modelparameters up-to-date? Do model parametersreflect land use changes that have occurredwithin the basin? Can the model or itsparameters be easily modified to reflect pendingland-use changes within the basin? Does themodelling system reflect flood control structuresand their operations within the basin? Are thereimportant hydrological processes occurring inthe basin that are not reflected in the existingforecast model? Does the forecast systemperform well for flooding but is inadequate tomeet routine or low flow forecast requirements?Is there a need to convert hydrological forecaststo water level (stage) using a hydraulic model?In general, is the existing modelling systemappropriate and sufficient to meet userrequirements?

Hydrological forecasting knowledge

Highly trained hydrologists produce reliablehydrological forecasts. Forecasters use real-timedata, knowledge of hydrology, knowledge of thehydrological modelling system and experiencein producing forecasts and warnings. Indetermining the operational readiness orhydrological forecast capability of a forecastcentre, the education, knowledge and skills ofthe forecasters are as important as the tools theyuse. Is the number of forecasters availablesufficient to handle the flooding situation? Dothe forecasters have sufficient education inhydrology and meteorology to appropriatelyapply the tools? Are they properly trained, anddo they understand the limitations of themodelling system being used? Do theforecasters know the users, how to contactthem, and what information they require forflood response actions? An assessment of theadequacy of the operational forecaster capabilityis important in determining how to improveflood forecast operations.

Forecasts

In order to produce a flood forecast forthe communities and locations at risk,there must be a hydrological modellingcapability that uses meteorological andhydrological data. Hydrological modelsuse real-time precipitation and streamflowdata. The models translate observedconditions into future stream conditions.Hydrological models or procedures varyin complexity, accuracy and ease of use.Simple hydrological models consist oftables, graphs or empirically derivedrelationships. More sophisticatedhydrological modelling systems use in-situdata, remotely sensed data, and multiplehydrological models that are integrated toproduce very accurate hydrologicalforecasts. Due to advances in GeographicInformation Systems and the availabilityof geo-referenced data, parameters ofsome hydrological models can now beestimated without having to relyexclusively on historical hydrological datafor model calibration. The evolution ofpersonal computer technology has pavedthe way for quite complex modellingsystems to be run on them. These systemsare easier to use, are easier to maintain,and are more affordable.

Current hydrological forecast systems arequite affordable and powerful. Thedegree of success associated with thesesystems is dependent on the amount oftraining received by the hydrologistsusing them. These systems are capable ofproducing a broad range of forecasts ofstream conditions that will occur in a fewhours to seasonal probabilistic outlookstargeted to months in advance for largerrivers. Model system selection dependson the amount of data available,complexity of hydrological processes tobe modelled, accuracy and reliabilityrequired, lead-time required, type andfrequency of floods that occur, and userrequirements.

61

62

Hydraulic models are often used to translatehydrological model-derived streamflow towater-level conditions. Hydraulic models arealso valuable in forecasting the streamflowconditions of large rivers where sufficientlead-time is accorded through translation ofupstream water levels to downstreamcommunities at risk. Such models can beinterfaced with geographical informationsystems to provide dynamic water levelconditions on maps of communities. Thesetypes of forecast products can be invaluable tocommunities and emergency organizations, asthey provide very precise information aboutareas that will be inundated and when.

Decision support

Hydrometeorological data and accurateforecasts are of no value if the forecasts donot reach users and if decisions are not madeas to the appropriate actions required.Hydrological forecasts and hydraulicconditions must be disseminated so thatdecisions can be made and actions taken toreduce the impact of the pending event.Decision support refers to everything fromforecasts reaching decision makers such as amayor of a flood-prone community to theoperator of a flood-control structure. Fordecision support to be effective, advancedplanning must define prescribed actionslinked to forecasted values.

Decision support systems vary from rules orprocedures that must be followed underprescribed conditions to mathematicaloptimization programmes. Such approachesdefine actions to be taken based on tradeoffsamong various options for water allocation.

Forecast output

Typically, calculations used in preparing aforecast are based on units of discharge,although some simplified systems correlateupstream with downstream water levels.

However, decision makers and the public aremost often concerned with water levels andvelocities at specific points, usually urbancentres. Forecasted flows can be converted towater levels and velocities using stage-discharge and stage-velocity relations,hydraulic models, or other techniques.Decision makers and emergency workersshould be consulted on their specific forecastrequirements.

In many cases, forecast water levels are givenaccording to a local vertical datum. This maybe convenient for some purposes but mayintroduce potential for confusion. With theadvent of global positioning systems, it ispossible to provide a geodetic datum at anylocation and this should be done.

The forecast water levels released to thepublic could be in several formats: tabular,hydrographs, or inundation maps. It is veryuseful to provide comparisons with theprevious year or with previous major floods.Inundation maps linked to databases canprovide information on individual propertiesand can be most useful for public awarenessand emergency services.

The forecast should be formally released andmade available to key agencies as well as themedia. The forecast should also be placed onInternet websites for easy access.

The points for which the forecast appliesshould be communicated very clearly. Forexample, the name of a city in the basinshould be identified, or in the case of verylarge cities, well-known points within the cityshould be specified.

Uncertainty in the forecast should berepresented accurately, but in non-technicallanguage. Phrases such as "if presentconditions continue…" are useful as are thosethat require simple statistical knowledge suchas "there is an 80% chance that…"

63

Guidelines for Reducing Flood LossesDissemination of forecastsand warnings

Forecast and warning dissemination isextremely important. Frequently, the lack ofability to disseminate warnings to thepopulation at risk is the weakest link in theintegrated system. Forecasts and warningsmust reach users without delay and withsufficient lead-time to permit response actionsto take place. Dissemination of forecasts andwarnings can be achieved through a variety ofcommunication methods. An inventory of thevarious communications media used by theforecast system will reveal the competency ofthe dissemination process. How are warningstransmitted to the public, to the flood controlagencies, to the emergency services and civilprotection organizations? Are communicationsystems reliable? What types ofcommunication modes are used (such assatellite, radio, meteor bursts, telephone orinternet)? How are communications linesmaintained? Are there backup modes ofcommunication? In what format arewarnings transmitted? Do users understandthe content of the warnings? These are a fewof the questions that need to be answered inassessing the performance of disseminationsystems.

Users

Who are the users? Understanding theneeds of users is fundamental to achieving asuccessful flood forecast, warning andresponse programme. What kinds of dataand information do they need? Where arethey? How do you reach them during theday or late at night or during a nationalholiday? How do they make decisions?

Establishing a user group association or aninventory of users is important for a wellfunctioning and effective forecasting system.The sophistication and needs of users canvary considerably. For example, thehydropower industry needs high-resolution

data, detailed hydrological forecasts for short-term as well as for longer time horizons.Emergency services groups and mediaorganizations need clearly stated warninginformation that defines the hazard and spellsout what steps the public must take tominimize their risk.

Notification and action

The entire process of establishing a floodforecast is of no value unless data andforecasts reach users. An effective fail-safeforecast dissemination system must beestablished to allow forecasts and warnings toreach users, wherever they are. Notifyingusers is often problematic because manycountries do not have communication systemsthat reach rural villages and othercommunities at risk. Internet is an effectiveworldwide communication system, but theuser must have access and be vigilant in orderto receive the warning. There are manyexamples of effective dissemination systemsbased on high-speed telecommunications thatuse satellite, microwave, radio, or meteorburst technology.

An effective flood-warning programme mustalso be linked to the media to reachpopulations inhabiting the areas at risk. Inmany cases, the media can provide aneffective means of re-broadcasting warningsand assist in response-orientedcommunications.

The payoff from a successful end-to-endflood forecast and response programme iswhen actions are taken to reduce the impactof the impending flood. Actions can be assimple as moving contents from the first floorof a person's house to the second floor,evacuating the flood plain, blocking roadsthat will be flooded, or closing floodgates of alevee system that protects a city. If nomitigation actions result from flood forecastsand warnings, society is simply paying moneyfor ineffective results.

65

Establishing an Integrated System

4

66

There are a number of steps that should befollowed in establishing an integrated floodforecast, warning and response system.These steps are very important and havebeen introduced in greater detail earlier inthese Guidelines. The intent of this sectionis to provide a brief overview of these steps.In doing so, there will be some reiteration ofpreviously introduced concepts and material.

The first step for a community, country orregion is to conduct an assessment of theexisting flood forecast programme. Each ofthe links or components of the forecastsystem should be evaluated as to itseffectiveness.

After the existing system has been assessed,a new and improved system can bedesigned. The new system design shouldstrengthen the weak links of the existingforecast system, meet the needs of the users,and provide sufficient accuracy and leadtime to reduce flood losses to the maximumpossible extent. Like any other project, thenew forecast system will be subject to costconstraints and must therefore concentrateon those improvements that will yield thegreatest benefits in terms of reducing humanand economic losses.

Frequently financial institutions supportingflood forecast modernization projects willrequire an economic analysis or feasibilitystudy to determine the benefits versus thecosts of the project and subsequentprogrammes. Usually there are significanteconomic gains that can be realized byinvesting in an integrated flood forecastsystem. For example the U.S. NationalOceanic and Atmospheric AdministrationNational Weather Service (NOAA/NWS) isproposing investing $US 60 million in theAdvanced Hydrologic Prediction Services(AHPS) project. The economic analysisdemonstrated benefits of $US 360 millionper year from reducing flood losses and

from providing forecasts to the watermanagement sector of the economy.

The following are steps required forestablishing an improved integrated system.Each of these components should beconsidered in the overall design withemphasis on strengthening the weakest linkswithin the existing system.

• Design improved meteorologicalobserving network

• Design improved hydrological network(precipitation and stream gauges)

• Automate the meteorological andhydrological networks

• Establish real-time communicationsystem to move data reliably from field tothe forecast office

• Establish operational networkmaintenance plan

• Determine feasibility of existing and newground-based radar for estimatingquantitative precipitation products

• Determine feasibility of usinggeostationary and polar orbiting satelliteproducts

• Integrate in-situ precipitation data withsatellite and radar precipitation estimates

• Establish hydrometeorological databaseand management system

• Select hydrological and hydraulic modelsappropriate for river basin conditions andneeds of the users

• Establish real-time linkages betweendatabases and modelling system

67

Guidelines for Reducing Flood Losses• Link numerical weather prediction

model products to the hydrologicalforecast system (QuantitativePrecipitation Forecasts and ClimateForecasts)

• Determine the training needs for newhydrological forecast methods versuscurrent forecaster knowledge

• Establish training programmes andmaterials

• Design real-time communications systemto disseminate routine forecasts andwarnings to target audiences (e.g.,communities, media, mayors,government officials)

• Establish user group networks andprotocols to interact with forecasters andsystem outputs to ensure forecastproducts are appropriately designed forthe users

• Establish an "Operations Concept" thatdefines how the hydrological forecastcentre will operate in routine operationsas well as during major flood episodes inthe improved system

• Establish response strategies withcommunities, emergency services, andcivil protectorate organizations

Once the design of the improved integratedsystem has been completed, this design mustthen be incorporated into a project proposalwith associated costs and time lines forapproval by the various governmentalentities involved, as well as by donor andfinancial institutions. Once approved, adetailed implementation plan must bedeveloped. It should show how the variouscomponents of the new system would becompleted and integrated into a sustainableforecast programme.

The science and technology required toproduce a fully integrated flood forecast andresponse system are available today. Thereare many systems now operating that haveachieved a high degree of integration andsustainability. Cooperation amongst levels ofgovernment, ministries, civil society andprivate industry is absolutely necessary toachieve an integrated programme.Interaction between meteorological andhydrological organizations is essential forestablishing a viable flood forecasting,warning and response programme.

68

Bibliography

General

Abramovitz, J. (1999), "Unnatural Disasters", World Watch, 1999 July/August. Worldwatch Institute, Washington,D.C.

Abramovitz, J. (2001), "Averting Natural Disasters" in: Brown, L., Flavin, C., and French, Hillary (eds.), State of theWorld 2001, Worldwatch Institute 2001, W.W. Norton & Company, pp. 123-142.

Affeltranger, B. (2001), "Public Participation in the design of local strategies for flood mitigation and control", IHP,Technical Documents in Hydrology No. 48, UNESCO, Paris.

Andjelkovic, Ivan (2001), "Guidelines on non-structural measures in urban flood management", IHP, TechnicalDocuments in Hydrology No. 50, UNESCO, Paris.

Arnold, Margaret and Kreimer, Alcira (eds.) (2000), "Managing Disaster Risk in Emerging Economies", DisasterRisk Management Series No. 2, World Bank, Washington, D.C.

Barrett, Curtis (1999), "Development of Global Integrated Water Management Systems", Journal of Management inEngineering, American Society of Civil Engineers, Vol. 15,No. 4, July/August.

Centre for Research on the Epidemiology of Disasters (CRED) (2002), "EM-DAT: The OFDA/CREDInternational Disaster Database - www.cred.be/emdat", Université Catholique de Louvain, Brussels.

Economic Commission for Europe (ECE) (ed.) (2000),"Guidelines on Sustainable Flood Prevention",September 2000, Geneva, submitted at the Meeting of the Parties to the Convention on the Protection and Use ofTransboundary Watercourses and International Lakes, Second meeting, The Hague, Netherlands, 23-25 March,2000.

Enarson, Elaine and Morrow, Betty Hearn (eds.) (1998), The Gendered Terrain of Disaster: Through Women'sEyes, Greenwood Publishing (forthcoming).

Enarson, Elaine (2000),"Gender and Natural Disasters", Working Paper I, International Labour Organization(ILO)/Recovery and Reconstruction Department, Geneva, September.

Enarson, Elaine (2001), "Gender Equality, Environmental Management, and Natural Disaster Mitigation", Reportfrom the On-Line Conference conducted by the United Nations, Department for Economic and Social Affairs,Division for the Advancement of Women, New York, November.

Freeman, Paul K.; Martin, Leslie A.; Mechler, Reinhard and Warner, Koko (eds.) (2002), "Catastrophesand Development. Integrating Natural Catastrophes into Development Planning", Disaster Risk ManagementWorking Paper Series No. 4, World Bank, Washington, D.C., April.

Gilbert, Roy and Kreimer, Alcira (1999), "Learning from World Bank's Experience of Natural Disasters RelatedAssistance", World Bank Paper Series No. 2, Disaster Management Facility, World Bank, Washington, D.C.

Hydrology Subcommittee of the Federal Interagency Advisory Committee (1985), "Guidelines onCommunity Flood Warning and Response Systems", USA, United States Geological Survey, Office of Water DataCoordination, Reston, Virginia.

Inter-Agency Secretariat of the International Strategy for Disaster Reduction (UN/ISDR) (2002),“Living with Risk - A global review of disaster reduction initiatives”, UN/ISDR, Geneva.

International Commission for the Protection of the Rhine (2002), "Non Structural Flood Plain ManagementMeasures and their effectiveness".

International Federation of Red Cross and Red Crescent Societies (1999), "Vulnerability and capacityassessment: International Federation Guide", IFRC Geneva, (English, French, Spanish, Arabic).

International Federation of the Red Cross and Red Crescent Societies (2001), "World Disasters Report2001", IFRC Geneva.

International Federation of the Red Cross and Red Crescent Societies (2002), "World Disasters Report2002", IFRC Geneva.

International Monetary Fund (IMF) (2002), "The World Economic Outlook (WEO) Database", IMF,Washington D.C.

McKellar, L., Freeman, P.K. and Ermolieva, T. (1999), "Estimating Natural Catastrophic Risk Exposure andthe Benefits of Risk Transfer in Developing Countries", In: Proceedings of the EuroConference on Global Changeand Catastrophic Risk Management: Flood Risks in Europe. IIASA, Laxenburg, Austria, 6-9 June.

Munich Re (2001), "Topics, Annual Review: Natural Catastrophes 2000", Munich Re, Munich.Parker, D.J. (ed.) (2000), "Floods Vol. I & Vol. II ", Routledge Hazards and Disasters Series, Routledge, London.United Nations Development Programme and United Nations Economic Commission for Latin

America and the Caribbean (UNDP/ECLAC) (1998), "A Preliminary Assessment of Damages Causedby Hurricane Mitch".

United Nations Economic and Social Commission for Asia and the Pacific (1999), "RegionalCooperation in the Twenty-First Century on Flood Control and Management in Asia and the Pacific", UnitedNations: New York.

69

Guidelines for Reducing Flood LossesUnited Nations Department of Economic and Social Affairs (2002), "Natural Disasters and Sustainable

Development: Understanding the links between Development, Environment and Natural Disasters", BackgroundPaper No. 5, submitted by the United Nations International Strategy for Disaster Reduction, for the Commissionon Sustainable Development, Second Preparatory Session, 28 January - 8 February 2002, New York.

United Nations, Department of Economic and Social Affairs, Division for the Advancement ofWomen (DAW) and Inter-Agency Secretariat of the International Strategy for DisasterReduction (UN/ISDR) (2001), " Environmental Management and the Mitigation of Natural Disasters: aGender Perspective", Report of the Expert Group Meeting, Ankara, Turkey, 6 - 9 November 2001.

U.S. Department of Commerce (2002), "Hurricane Reconstruction Program-Central America and the DominicanRepublic, FINAL REPORT", Washington, D.C.

World Bank (2001), "Managing Economic Crisis and Natural Disasters", in World Development Report 2000/2001,(Chap. 9), World Bank, Washington, D.C.

World Meteorological Organization (WMO) (1999), "Comprehensive Risk Assessment for Natural Hazards",WMO/TD No. 955, Geneva.

Regional and country experiences

Asian Disaster Preparedness Center (ed.) (2002), Asian Disaster Management News, Drought Management,Vol. 8, No. 3, July-September.

Asian Disaster Preparedness Center (ed.) (2002), Asian Disaster Management News, Flood Preparedness, Vol. 8,No. 2, April-June.

Asian Disaster Preparedness Center (ed.) (2002), Asian Disaster Management News, Information Sharing andNetworking in Disaster Management, Vol. 8, No. 1, January-March.

Asian Disaster Preparedness Center (ed.) (2001), Asian Disaster Management News, Linking Local Governanceand Community-Based Disaster Management, Vol. 7 No. 4, October-December.

Asian Disaster Preparedness Center (ed.) (2001), Asian Disaster Management News, Reducing the Impact ofDisasters on Tourism, Vol. 7, No. 2-3, April-September.

Asian Disaster Preparedness Center (ed.) (2000), Asian Disaster Management News, Networking in DisasterManagement, Vol. 6, No. 3-4, July-December.

Asian Disaster Preparedness Center (ed.) (2000), Asian Disaster Management News, Public Health in Disasters,Vol. 6, No. 2, April-June.

Asian Disaster Preparedness Center (ed.) (2000), Asian Disaster Management News, Reconstruction afterDisaster Vol. 6, No. 1, January-March.

Asian Disaster Preparedness Center (ed.) (1999), Asian Disaster Management News, Role of Local Governmentin Disaster Management Vol. 5, No. 1, February.

Asian Disaster Preparedness Center (ed.) (1998), Asian Disaster Management News, Extreme Climate EventsVol. 4, No. 1, October.

Asian Disaster Preparedness Center (ed.) (1997), Asian Disaster Management News, Gender and Disasters, Vol.3, No. 3, November.

Asian Disaster Preparedness Center (ed.) (1997), Asian Disaster Management News, Community BasedApproaches in Disaster Management, Vol. 3, No. 2, June.

Asian Disaster Preparedness Center (ed.) (1997), Asian Disaster Management News, Networking, Vol. 3, No. 1,February.

Asian Disaster Reduction Center (ADRC) (2001), "Information Technology For Disaster Management",International Paper No.1, August.

Asian Disaster Reduction Center (ADRC) (2002), "Report of Regional Workshop on Networking andCollaboration among Non-Governmental Organizations of Asian Countries in Disaster Reduction and Response",20-22 February, 2002, Kobe, Japan.

Asian Disaster Reduction Center (ADRC) (2001), Annual Report No. 4. Asian Disaster Reduction Center (ADRC) (2001), "Survey Report of Disaster Prevention and Management

Frameworks in Northeast Asian Regional Government" (China, Japan, Russia, Republic of Korea, Mongolia),February.

Asian Disaster Reduction Center (ADRC) (2001), "Community-Based Flood Mitigation Project: The Case ofBandung City/Indonesia", Project Report, No. 1.

Bureau of Transport and Regional Economics, Commonwealth of Australia (2002), "Benefits of FloodMitigation in Australia", Report 106, Canberra.

Department of Land and Water Conservation, Government of New South Wales/Australia (2001),"The NSW Floodplain Management Manual: the management of flood liable land", Sydney.

International Commission for the Protection of the Rhine (2002), "Non Structural Flood PlainManagement: Measures and their Effectiveness", Koblenz.

Mekong River Commission Secretariat (2001), "Mekong River Commission Strategy on Flood Management andMitigation", Phnom Penh, November.

Neto, Frederico (2001), "Alternative approaches to flood mitigation: a case study of Bangladesh", in: NaturalResources Forum 25, No. 4, November, pp.285-297, United Nations.

70

On-line libraries on natural disasters

Asian Disaster Preparedness Center, Bangkok/Thailandhttp://www.adpc.ait.ac.th/infores/doc.htmlThe Center also publishes a quarterly newsletter, Asian Disaster Management News. This newsletter,designed to serve as a communication channel for the disaster management community in the Asian and Pacificregions, is disseminated in print to more than 2,000 people. The newsletter can be accessed through the Center'sWebsite.

Asian Disaster Reduction Center, Japanhttp://www.adrc.or.jp/adrc_events.asp

Disaster & Social Crisis Research Networkhttp://www.apu.ac.uk/geography/d&scrn/

Gender and Disasters Networkhttp://www.anglia.ac.uk/geography/gdn/resources/bibliographies.html

International Federation of Red Cross and Red Crescent Societieshttp://www.ifrc.org/publicat/

Natural Hazards Research and Applications Information Center, University of Colorado,Boulder/USAhttp://www.colorado.edu/hazards/litbase/litindex.htm

Pacific Disaster Centre, Hawaiihttp://www.pdc.org/pdc/pub/frmain07.html

Pan American Health Organization/Regional Office of the World Health Organizationhttp://www.paho.org/english/PED/catalog.htmhttp://www.paho.org/english/ped/about-vdl.htm

Reliefwebhttp://www.reliefweb.int/w/rwb.nsf/vLND

South Pacific Regional Environment Programme (SPREP)http://www.sidsnet.org/pacific/sprep/publicat_.htm

United Nations International Strategy for Disaster Reductionhttp://www.unisdr.org/unisdr/isdrpub.htm

World Bank, Disaster Management Unithttp://www.worldbank.org/dmf/

World Bank, ProVentionConsortiumhttp://www.proventionconsortium.org/publications.htm

Periodical publications (journals, newsletters)

The Australian Journal of Emergency Management, The Australian Emergency Management Institute (Rob Fleming),[email protected]

Disasters: Preparedness and Mitigation in the Americas, Publication of the Pan American Health Organization (PAHO),Washington, D.C. [email protected]; http://www.paho.org/english/ped/pedhome.htm

Hazards International: Newsletter for Safety, Health & Environment Worldwide, Coventry, UK;[email protected]

International Civil Defense Journal, Geneva, Switzerland; [email protected] Journal of Mass Emergencies and Disaster, Articles index: http://www.usc.edu/sppd/ijmed/;

http://www.usc.edu/schools/sppd/ijmed/articles.htmlISDR Highlights, Inter-Agency Secretariat of the International Strategy for Disaster Reduction (UN/ISDR), Geneva,

http://www.unisdr.org, [email protected] Informs, Asia/Africa/LAC, Inter-Agency Secretariat of the International Strategy for Disaster Reduction

(UN/ISDR), Geneva, http://www.unisdr.org, http://www.unisdrafrica.org, http://www.eird.orgJournal of Contingencies and Crisis Management, Leiden University, The Netherlands

[email protected] Hazards: Journal of the International Society for the Prevention and Mitigation of Natural Hazards, Kluwer

Academic Publishers

71


Annex

Case Study 1: Community Education

Practical experiences in preparing a community for a disaster in thePhilippines

As a hazard strikes a community, the degree of preparedness of the local population and thelocal authorities sometimes spells the difference between the occurrence of a disastrous eventor one that the community can cope with. In areas where a hazard regularly "visits", thepopulation build methods for coping with it, even though it may be in an unorganized way.The demand for survival forces people to "invent" ways to withstand a disaster. On the otherhand, local authorities who already know the cycle of disaster management often lack theskills and/or resources to undertake activities to operationalize the measures for riskreduction. Such is the case in the Philippines, which has comprehensive legislation toaddress disaster events. The provisions of this law mandate the national, regional,provincial, city/municipal, and village officials to organize "Disaster CoordinatingCouncils/Committees" (DCCs) with delineated functions and to conduct a series of activitiesto operationalize these functions.

Lack of or limited resources at all governmental levels are cited as the usual reason for thelack of support to the formation of these village structures. However, this situation can beimproved if the local authorities encourage the participation of the local population. Thequality of participation that seems to be most suited to the formation of an involvedcommunity is one that is not forced or coerced.

The village of Talba, in Central Luzon, Philippines, with a population of 779 families or4,674 people, was situated along a river through which lava from Mt. Pinatubo had flowed.The possibility of an overflow of the river in the near future was a real danger. A non-governmental organization (NGO) focusing on disaster management was requested by ahealth-service NGO working in Talba to assist in the training and setting-up of a disastermanagement group in the community. The NGO established a community-based group,known as Barangay Disaster Response Organization. The participation of a Barangaycouncilman in this affair facilitated the interface between the Barangay DisasterCoordinating Committee and the people's organization, by making the members of the lattergroup also members of the committees of the former group. The Barangay DisasterResponse Organization, however, maintained its identity by holding regular meetings withother organizations and stakeholders in the village.

Among the first activities of the community's disaster mitigation plan were the sandbaggingof the area along the river's route and the construction of an "uplifted" walking path for theresidents, which was also made of sandbags. The sandbags along the shoreline wereintended to slowdown the flooding of the area in case a rampaging lava flow was to strike thevillage. In 1995, a lava overflow destroyed the village of Talba. In that event, thegovernment communication system was disrupted and failed to give the proper warning tothe residents. It was the parallel warning system developed by the community people that

72

warned them on time to evacuate the area and avoid any loss of life. Resources of thecommunity, such as privately owned small boats, jeeps and a truck, were used to move thevillage's population to safety.

In the Talba experience, the local authorities were "open" to the engagement of the people'sorganization and agreed to a cooperative approach. The involvement of a Barangaycouncilman in the people's organization enhanced this cooperation. This also points to thewillingness of some local authorities to share their responsibilities with the local populace.This kind of cooperation enhances their relationship. Allowing the people's organization tomaintain its identity, instead of co-opting it or forcing its integration with the governmentstructure increased the "goodwill" and facilitated mutual support between the two sectors. Atrained and organized village community can undertake lifesaving measures thatcomplement the goals of the local authorities. They can initiate activities that can besustained even after the occurrence of disasters. Therefore, in areas where active civilorganizations or groups can be engaged to complement a local government's limitations,their participation has been proven to ensure the community's welfare in the face of disaster.

73


Case Study 2: Regional Cooperation in Southern Africa

Policy commitment to flood risk reduction

The Southern African Development Community (SADC) is comprised of 14 member stateswith a population of approximately 200 million: Angola, Botswana, Democratic Republic ofthe Congo, Lesotho, Malawi, Mauritius, Mozambique, Namibia, Seychelles, South Africa,Swaziland, Tanzania, Zambia and Zimbabwe.

Since the devastating floods that affected much of the region in 2000-2001, particularly inMozambique, a process of intense regional cooperation has been started at the highestpolitical level. This process is focusing mainly on improved technical collaboration includinganticipating, mitigating andresponding to sudden-onset naturalhazards, such as cyclone-triggeredtrans-boundary floods, and allocatingmore resources to risk reduction. Fora long time, the water sector hasfocused on the development ofcooperative agreements on sharedriver basins, but the floods of 2000and 2001 underlined the need forpaying greater attention to regionalflood risk, in addition to recurrentdrought. The need for inter-statecooperation associated with water-related hazards in Southern Africa isparticularly acute, as there are morethan ten shared watercourses in theregion.

As a starting point, an Extraordinary Summit for SADC Heads of State and Governmentwas convened in Maputo, Mozambique in March 2000 to review the impacts caused by thefloods across the region. In May 2000, the SADC Sub-Sectoral Committee on MeteorologyMeeting was convened and the Directors of National Meteorological and HydrologicalServices (NMHS) in the SADC countries recommended a regional project to beformulated to address and strengthen the local capacities of national meteorological andhydrological services for early warning and disaster preparedness. In addition, the SADCCommittee of Ministers for Water asked for a strategic and coordinated approach to bedeveloped to manage floods and droughts within the region. By August 2000, the SADCCouncil of Ministers approved an overarching SADC Disaster Management Framework foran integrated regional approach to disaster management and established a full TechnicalSteering Committee on Disaster Management. By the end of 2001, SADC had developedand set in place a multi-sectoral disaster management strategy for the region.

The successful implementation of this disaster reduction strategy rests on interaction amongdifferent technical and administrative networks across Southern Africa. The SADC WaterSector Coordination Unit formulated an integrated Strategy for Floods and Drought

Pho

to: C

.Bla

ck a

nd D

.Rev

ol, I

FR

C

Rain and flooding in February 2000 have left much of central Mozambique under water

74

Management in the SADC Region that will be implemented over a four-year period. Thestrategy focuses on preparedness and contingency planning, early warning and vulnerabilityinformation systems, mitigation measures, response activities and recovery strategies. Theprocess involves regular consultations through which the heads of disaster management,early warning, and meteorological units and water authorities from individual countries inSouthern Africa will meet with SADC technical counterparts in order to monitor progressand address impediments to reduce drought and flood-related disasters. Fifty real-time andcoordinated data collection stations are currently being installed in eleven Southern Africancountries under the EU funded SADC Hydrological Cycle Observing System (SADC-HYCOS). These stations are expected to make major improvements in the timelyavailability of data and to provide more real-time data transmission and the dissemination ofessential transboundary hydrological information for flood forecasting. The project is beingimplemented by the SADC Water Sector Resources in association with the nationalhydrological services of the participating countries.

75


Case Study 3: An Instructional Programme for the Local Level

A disaster awareness and response instructional programme for people atthe local level in Vietnam

Vietnam is one of the most disaster-prone countries in the world. The 1996 flood season wasparticularly devastating: typhoons, tropical storms, whirlwinds, landslides and floods affectedalmost every province in the country, causing $US 655 million in damages and taking morethan 1,000 lives. In 1997, Typhoon Linda alone caused almost $US 600 million in damagesto the southern provinces. More significantly, 2,900 people were either killed or reportedmissing. In 1998, Vietnam faced not only typhoons and floods, but also severe drought thatspread nationwide and lasted until May 1999. Forest fires were also widespread. In responseto such threats, the United Nations Development Programme (UNDP), the Ministry ofAgriculture and Rural Development, and the Central Committee for Flood and StormControl (CCFSC) are working together to establish strategies for disaster preparedness,prevention, and mitigation. Strengthening national capacities to plan for and respond tonatural disasters is a further target.

The new DisasterManagement projectbuilds on the success of aprevious UNDP projectthat established anationwide water disasterinformation andmonitoring system focusedat the provincial level thatextends training in disasterawareness and responseright down to the districtand commune levels. Thenew project is extendingthis water disastermanagement capability toother disasters, includingdrought, seawaterintrusion, and forest fires.

The major purpose of this EU-UNDP funded pilot training project was to introducedisaster awareness and preparedness to the elementary school system in Vietnam. Schoolchildren in selected communes are being taught how to mitigate disaster damage in theirhouseholds and families. In addition to educating school children, this "grassroots" approachis also aimed at developing synergetic effects, such as fostering a greater awareness of naturaldisasters within families and their communities. Three provinces in Vietnam (Thanh Hoa,Quang Tri, and Long An Provinces) were selected. The three main objectives beingpursued were: (1) to develop a community-based disaster awareness and preparednesstraining programme that, if successful, could be replicated nationwide; (2) to establish anucleus of Master Trainers; and (3) to strengthen the institutions that deal with disaster

Pho

to: E

CH

O

Training of school children, Vietnam

76

management in Vietnam. Implementation steps of this training programme included: settingup a Steering Committee and a Working Group; drafting and signing a contract with thelocal Vietnam Red Cross Society; creation, design, and constant revision of training material;training of Master Trainers; and training of teachers and children in selected provinces.

Based on the review of books and student knowledge at the grade 4 and 5 levels, a children'sbook and a teacher's book were prepared and distributed to schools. "Disaster bags" weredescribed and explained in the training materials: they are to be used by the pupils' familiesto store, and thus preserve, important documents. In addition, a videotape for educationalpurposes was produced by a television station in Hanoi, dealing specifically with disasters inVietnam and incorporating many of the lessons contained in the training materials.

The Vietnamese Red Cross was responsible for organizing and conducting the training ofschoolteachers. A total of 288 schoolteachers in all three provinces received the training.Following the training of teachers, the provincial Red Cross worked with the districts andschools to organize the teaching of fourth and fifth graders from selected schools. A total of18,755 pupils were taught. The teaching was spread over a four-week period. The trainingprogrammes were not integrated into the existing curriculum; rather they were presented asextra courses added to the regular curriculum. These courses were taught over a weekend,when the pupils would not ordinarily be in school.

77


Case Study 4: Access to Information - The RANET Project

RANET is a project of several partners aimed at making climate and weather relatedinformation more accessible to rural populations and communities in Africa. RANETprovides a radio-internet pathway between scientific results and individuals in remotelocations for whom "early warning" information might matter greatly. The programmecurrently operates in Africa and is exploring appropriate roles in Asia and the Pacific. Thegoal is to improve access to climate and weather related material through a variety ofactivities, while also developing a system through which meteorological services candisseminate their own information to rural communities.

RANET endeavours to make available to national, regional, and local levels the tools andinformation required for decision-making. All activities of RANET are based on aparticipatory approach and are done in conjunction with, and with the approval of, thecommunities themselves and the national meteorological and associated services.

Technological and scientific advances in recent decades have provided not only a goodunderstanding of climate and weather conditions, but also a wide variety of observations andforecasts that can be used in efforts to manage systems sensitive to meteorological events. Atpresent, many rural populations most in need of hydro-meteorological and environmentalinformation are not able to access the information already produced by national, regional,and various international organizations. The RANET Programme was created and designedspecifically to address the problem of information access and interpretation at the level ofrural communities.

RANET identifies and trains partners in the use of various technologies that are mostappropriate for their information needs and are serviceable in their area. Aside fromidentifying a variety of techniques, RANET works to gain access for rural populations to"common networks"- large systems likely inaccessible by any one group, but usable byRANET and its partners when used together. Additionally, RANET focuses on integrating

Sour

ce: R

ANE

T

RANET information cycle: Global, regional, nationaland local information isgathered from varioustechnologies throughdifferent methods and thenblended in a singlebroadcasting via Radio

78

existing networks thereby reinforcing local, existing capabilities rather than developing new,resource intensive and unsustainable networks.

Many development projects with a component of telecommunications technology arevulnerable unless appropriate and sustainable solutions are identified and deployed. InAfrica one of the more successful systems has been an integration of new and existinganalogue (FM/AM) radio stations with new digital radio satellite technologies, as providedthrough the World Space Foundation. Taken together, these technologies allow for both localknowledge and new information to be used in support of rural populations. Radio is one ofthe most pervasive technologies in use throughout the globe, and RANET's inclusion ofradio in its network design helps to ensure the programme builds upon existing capabilities,is community owned and operated, locally relevant, and therefore more sustainable.

The lessons learned by RANET underscore the need for a period of consistent follow-upand technical support until the introduced systems, or newly integrated networks, can befully supported locally (or within a region), and therefore considered sustainable. Such atransition period means identifying serviceable technologies, identifying existing networksand capabilities, training, and the development of a support community. For this reasonRANET is embarking on new education and training programmes, which allow participantsto solve problems that arose during implementation (including revenue generation andsustainability), learn from each other's experiences, and build upon the basic knowledgegained in the initial training sessions and project development.

Contact:General Information: [email protected] Africa: [email protected]: [email protected]: [email protected]

79


Acronyms

ACMAD African Centre of Meteorological Application for DevelopmentADRC Asian Disaster Reduction CenterAHPS Advanced Hydrologic Prediction Services project of the U.S. National Oceanic

and Atmospheric Administration National Weather ServiceCCFSC Central Committee for Flood and Storm Control in VietnamCRASH Comprehensive Risk Assessment for Natural HazardsCRED Centre for Research on the Epidemiology of DisastersDCCs Disaster Coordinating Councils/CommitteesDEM Digital Elevation ModelDTM Digital Terrain ModelENSO El Niño Southern OscillationECLAC United Nations Economic Commission for Latin America and the CaribbeanESCAP United Nations Economic and Social Commission for Asia and the PacificEM-DAT Emergency Events Database administrated by CRED,

University of Louvain, BelgiumEU European UnionGDP Gross Domestic ProductGIS Geographical Information SystemsGTS Global Telecommunication SystemHYCOS Hydrological Cycle Observing SystemIATF/DR Inter-Agency Task Force on Disaster ReductionIMF International Monetary FundIPCC Intergovernmental Panel on Climate ChangeISDR International Strategy for Disaster ReductionIWRM Integrated Water Resources ManagementNGO Non-governmental OrganizationNMHS National Meteorological and Hydrological ServicesOFDA Office of U.S. Foreign Disaster AssistanceQPE Quantitative Precipitation EstimationQPF Quantitative Precipitation ForecastingSADC Southern African Development CommunityUNDESA United Nations Department of Economic and Social AffairsUNESCO United Nations Educational, Scientific and Cultural OrganizationUNDP United Nations Development ProgrammeUN/ISDR Inter-Agency Secretariat of the International Strategy for Disaster ReductionUSAID United States Agency for International DevelopmentWEO World Economic OutlookWMO World Meteorological Organization


I S D RInternational Strategy

for Disaster Reduction

A contribution to the International Strategy for Disaster Reduction (ISDR)

United Nations

UN Department of Economic and Social Affairs (DESA)Division for Sustainable Developmentwww.un.org/esa/sustdev

UN Inter-Agency Secretariat of the International Strategy for Disaster Reduction (UN/ISDR)www.unisdr.org

National Oceanic and Atmosphere Administration (USA NOAA)www.noaa.gov