PRESENTATION ON

DROUGHT

WELCOME TO OUR PRESENTATION

LIST OF MEMBERS

TULSHI RANI ROY 61

WAHIDUL ISLAM 63

MST TAHMINA SIDDIQUA 59

ZAKIA AFSANA 64

MST TASLIMA NASRIN 60

Group No: 09

Throughout this presentation you will learn

content

IntroductionTo drought

Drought in BD

Drought index

SPICauses of Drought

Types of drought

Mathematical analysis of Drought

Effects of Drought

Drought, poverty, food

security

Drought Is

A lack or of for an unusually

period of , involving

less than the usual over 3 months

A lack or shortage of water for an unusually long period of time, involving 50% less than the usual rainfall over 3 months

What do you mean by drought?

The word drought instantly brings image of dry, parched land, no rainfall, crop failures, starvation and bad living conditions to our mind.

In simple terms, drought is a condition of acute scarcity of water, food, fodder, and employment due to scanty rainfall in an area.

DROUGHT

Definition of drought1. CG Bates (1935) “ Annual precipitation is 75% or less of normal precipitation and monthly precipitation 60% or less of normal monthly precipitation.”2. British Rainfall Organization (1936) “Absolute drought: when are at least 15 consecutive day with less than 0.01inch of rainfall per day.Partial drought: When there are at least 29 days having mean rainfall of 0.01 inch or less.Dry spell: When 15 consecutive days receive less then 0.04 inch of rainfall per day.”

Definition of drought

3. J.C Hoyt (1936) “Annual and monthly rainfall is less then 85% of normal rainfall.”4. V.A Conard (1944) “period of 20 or more consecutive days without inch precipitation in 24 hours.”5. D.A Ramdas (1950) “ When rainfall for a week is half normal or less.”6. A.J Henry (1960) “ 21 days or more when rainfall is 30% or less of average rainfall. Extreme drought occur when rainfall is less then 10% of average rainfall for 21 days or more.”

How a drought starts

A drought starts when total rainfall is well below

average for several months.

Other signs of drought include:

Very dry soil

Trees have a sign of dying

Weather getting hotter and hotter

Very dry soil

Drought causes can be classified in two way. These are…

Natural

Global Warming

Deficiency of Rainwater

Weather (hot + dry)

EL-NINO

Soil Erosion

CA

USE

S O

F D

RO

UG

HT

This has increased the average temperature and caused climate changes to the earths atmosphere and also causes

drought.

There are fore types of drought. These are follows:

Meteorological drought

Hydrological drought

Agricultural drought

Socioeconomic drought

Types of drought

This kind is usually determined by the general lack of moisture in the weather such as lack of precipitation, and the play of other weather conditions such as dry winds, high temperatures and so on. It is expressed in relation to the average conditions of the region over a long period of time. It is usually an indicator of potential water crisis if the condition is prolonged. Meteorological drought can begin and end immediately.

Meteorological drought

This is when atmospheric moisture is reduced to the extent that soil moisture is affected. Here, crops and animals are affected and evapotranspiration is also affected. It is often the signs one sees when a meteorological drought is at play, but not before a hydrological drought.

Agricultural drought

This is when there is a deficiency of surface water and ground water supply in a region, often as a result of less precipitation, excessive reliance on surface water for farming, energy and other needs. Hydrological drought does not usually occur at the same time as meteorological drought. In a way, this decline in the quantity and quality of surface and sub-surface water is the effect of meteorological drought.

Hydrological drought

This condition is when some supply of some goods and services such as energy, food and drinking water are reduced or threatened by changes in meteorological and hydrological conditions.

Sometimes it is even made worse by growing populations and excessive demands of such goods, to the point that it creates stress on the little water available.

It takes a very long time for this kind of drought to get into full gear, and a long time to recover from it.

Socioeconomic drought

IDM(Indian Meteorological Department) stated that there are two type of drought

1. Severe drought: when the deficiency of rainfall excite 50% from normal rainfall

2. Moderate Drought: When the deficiency of rainfall between 25% and 50% of normal rainfall.

OTHER TYPES….

Types Of Drought And Their Impacts Over Time, From Onset Of Drought To Realization Of Impacts…….

Drought affects all parts of our environment and our communities. The many different drought impacts are often grouped as “economic,” “environmental,” and “social” impacts. All of these impacts must be considered in planning for and responding to drought conditions.

Let's take a closer look at all kinds of drought impacts.

Farmers may lose money if a drought destroys their crops.

If a farmer's water supply is too low, the farmer may have to spend more money on irrigation or to drill new wells.

Ranchers may have to spend more money on feed and water for their animals.

Businesses that depend on farming, like companies that make tractors and food, may lose business when drought damages crops or livestock.

People who work in the timber industry may be affected when wildfires destroy stands of timber.

Businesses that sell boats and fishing equipment may not be able to sell some of their goods because drought has dried up lakes and other water sources.

Economic impacts are those impacts of drought that cost people (or businesses) money. Here are just a few different examples of economic impacts: 

Power companies that normally rely on hydroelectric power (electricity that's created from the energy of running water) may have to spend more money on other fuel sources if drought dries up too much of the water supply. The power companies' customers would also have to pay more.

Water companies may have to spend money on new or additional water supplies.

Barges and ships may have difficulty navigating streams, rivers, and canals because of low water levels, which would also affect businesses that depend on water transportation for receiving or sending goods and materials.

People might have to pay more for food. 

Drought also affects the environment in many different ways. Examples of environmental impacts include:  Losses or destruction of fish and wildlife

habitat Lack of food and drinking water for wild

animals Increase in disease in wild animals, because

of reduced food and water supplies Migration of wildlife Increased stress on endangered species or

even extinction Lower water levels in reservoirs, lakes, and

ponds Loss of wetlands More wildfires Wind and water erosion of soils Poor soil quality 

Social impacts of drought are ways that drought affects people’s health and safety. Examples of social impacts include: Anxiety or depression about

economic losses caused by drought Health problems related to low

water flows and poor water quality Health problems related to dust Loss of human life Threat to public safety from an

increased number of forest and range fires

Reduced incomes People may have to move from

farms into cities, or from one city to another

Fewer recreational activities

DROUGHT AND HEALTH

Comparison in normal and drought condition health

DROUGHT, POVERTY AND FOOD SECURITY

Understanding drought and environment.

Water conservation. Pollution prevention. Storing and moving water. Rainwater harvesting. Afforestation. Geographical shifts of agricultural

system. Improve irrigation system. Climate-proofing rainfall based system. Computer based method should be used. Digging water reservoir. Artificial rainfall.

PREPARDNESS AND MITIGATION PLANNING FOR DROUGHT

DROUGHT INDEX

Precipitation Effective Index(PEI):

Following categories of the climate types have been defined on the basis of PEI.

Climate Type Vegetation PEI ValuesWet Rain Forest >127Humid Forest 64- 127Sub Humid Grass and 32- 63Semi Humid Steepen 16- 31Arid Desert <16

Tools and Techniques for drought assessment

Satellite derived drought indicators calculated from satellite-derived surface parameters have been widely used to study droughts. Remote sensing and GIS technique is increasingly being regarded as a useful drought detection technique, as evidenced by its use across many parts of the world.Some tools and technique for analysing drought using RS and GIS…. Standardized Precipitation Index (SPI) Normalized Difference Vegetation Index (NDVI) Vegetation Condition Index (VCI) and Temperature Condition Index (TCI)

Standardized Precipitation Index (SPI), a tool derived by Tom McKee (1993) et al., a measure of meteorological drought has been calculated from the available rainfall data collected by the Bangladesh Meteorological Department. Mathematically, SPI is calculated based on the following equation

where, Xi is monthly rainfall record of the station; Xm is rainfall mean; and σ is the standard deviation

Standardized Precipitation Index (SPI)

METEOROLOGICAL DROUGHT RISKS CLASSIFICATION USING SPI VALUES (MCKEE ET AL., 1993)

SPI Values class Probability

2.0 and more Extremely wet 0.977–1.000

1.5 to 1.99 Very wet 0.933–0.977

1.0 to 1.49 Moderately wet 0.841–0.933

-.99 to .99 Near normal 0.841–0.933

-1.0 to -1.49 Moderately dry 0.067–0.159

-1.5 to -1.99 Severely dry 0.023–0.067

-2 and less Extremely dry 0.000–0.023

Drought in Bangladesh

Drought in Bangladesh

The northern region of Bangladesh has in recent decades has been afflicted by recurrent and severe droughts, which in turn often led to intense food insecurity, known locally as Monga.

Every year, generally from mid-September through mid-November, this crisis occurs. People call the period Mora Kartik, meaning the month of death and disaster.

Too little water in the rivers during the dry seasons and less rainfall creates drought situations.

Statistics show that 92% of water in Bangladesh comes via external rivers and only 8% is local rainfall. The initial watersheds of all the major rivers in the region run through neighbouring India, making Bangladesh is heavily dependent on India for the availability of water resources. These rivers are the lifeline for agriculture, industry and the domestic sectors.

Drought in Bangladesh

The construction of barrages, hydroelectric dams, and other structural interventions in the upstream of these rivers heavily obstruct the normal flow of water towards Bangladesh. India often exploits these structures to withdraw water in the dry months (generally from March to May) for irrigation, energy production and economic uses. It creates tremendous stress on surface water resources in the northern districts of Bangladesh and causes a significant decrease in groundwater recharge, resulting in the depletion of soil moisture.

The scarcity of water in these areas has also been exacerbated by the low and uneven distribution of rainfall in recent years due to the effects of climate change.

Drought in Bangladesh

According to UNDP report the amount of water use per person is 46 litters per day

According to Bangladesh Meteorological Department “There was 21 per cent less rain during the monsoon period from June to August in 2009 and the northern districts suffer from drought”.

In Rangpur region 92 core litters/day water is extracted

11 litters/sec Water extracted by deep tubewells and sallow and deep tubewells run 180 and 175 days respectively in a year.

Drought in Bangladesh

Drought is one of the major environmental stresses in the north that drastically limits the grain yield of rice, a staple food of Bangladeshi people. This causes a lot of people to become unemployed and fall into acute food shortage between late July and early November.

During this interim period, there are no alternative agricultural activities left for people and the small non-agricultural sector cannot absorb the seasonally unemployed labour force. Hence, food insecurity in the region is associated with yield reduction in rice and non-availability of wage employment.