Integrated Watershed Management

Towards Sustainable Solutions in Africa

A. Bahri, H. Sally, R.E. Namara, M. McCartney,

S.B. Awulachew, B. van Koppen, and D. van Rooijen

International Water Management Institute

6th Biennial Rosenberg International Forum on Water Policy

June 23-27, 2008

Zaragoza, Spain

OUTLINE

D LAND, WATER & LIVELIHOODS CHALLENGES IN

SUB-SAHARAN AFRICA

D INTEGRATED APPROACH TO WATERSHED

MANAGEMENT

D CASE STUDIES

D CONCLUSIONS AND POLICY IMPLICATIONS

LAND, WATER & LIVELIHOODS CHALLENGES IN SUB-SAHARAN AFRICA

The percentage of the population living on less than $1 a

day

0

10

20

30

40

50

SSA SA EAP LAC ECA MNA

perc

en

tag

e

1990

1995

2001

SSA is the poorest region in the world – and getting poorer

(Source: NEPAD 2005, based on WB data)

GDP, Ag GDP and Population growth % 1980-2003

0

1

2

3

4

5

6

7

8

East Asia & Pacif ic Sout h Asia Middle East & Nor th

Af r ica

Lat in Amer ica &

Car ibbean

Sub-Saharan Afr ica

GDP grow th (annual %)

Ag value added (annual grow th %)

Population grow th %

Population growth in SSA has exceeded the growth

of both overall and agricultural GDP, so that

the population has become poorer

(Source: World Bank)

Water storage mitigates variability

Low per capita storage (m3/capita)

6150

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

4 43

746 1287

1406 2

486

3255

4729

-Very little water

storage has been built in Africa. Increased storage could reduce poverty and improve health

Kenya

Eth

iop

ia

South

Afr

ica

Tha

iland

Lao

s

Chin

a

Bra

zil

Aust

ralia

Nort

hA

merica

World Bank (2003)

Agricultural Water Management

D 3.8% water withdrawals for agriculture (3.6%), water

supply and energy.

D 183 million ha (Mha) (6%) of the total area under

cultivation:

D 97% of total cultivated area under rainfed. Over 90% of

the agricultural population dependent on green water.

D 21% (39.4 Mha) of total cultivated area potentially

irrigable. 9 Mha (5%) under water management. 7 Mha

under irrigation.

D Considerable scope for improved agricultural

production and food security through irrigation and

rainfed agriculture

Transboundary River Basins in Africa Water resources management means transboundary management

•Very high water inter­

dependence: 53 sovereign

states sharing 63

transboundary river basins

• Containing 93% of the total

water

• Covering 61% of the surface

area

• In which 77% of the human

population live

Trends and challenges of integrated watershed management

1. Development and operation of water systems and structures, largely for irrigation.

2. Mid 1990s, water management placed into the context of river basins.

3. IWRM, IRBM, INRM, IWM, ICM, …:

D Holistic, integrated, and participatory approaches

D Based on hydrological and bio-geophysical units

D Link land and water development

D Link social and economic development with protection of natural ecosystems

The Catchment Perspective

Return water flow

Virtual water flow

(Adapted from Falkenmark, 2002)

CONCEPTUAL MODEL OF UPSTREAM-DOWNSTREAM INTERACTIONS (after Kirkby, In CPWF, 2003)

Historical evolution of integrated watershed management in Africa

Integrated watershed management in Africa

D Most African countries engaged in WM and in IWRM.

D Some have however moved to a state-wide approach.

D How much water should be allocated to agriculture, other uses, and for environmental uses still a subject of debate.

D There are major differences in countries’ needs and development stages: focus on how to attain the MDGs vs environmental protection and restoration.

D Most African international basin organizations ineffective (AfDB, 2007). Issues of treaties unresolved and national interests prevailing.

CASE STUDIES

1. Balancing inter-sectoral water demands

in the Rufiji Basin in Tanzania

2. Water management in urban watersheds

3. The Nile – an example of multi-national

water management

Great Ruaha River

Target flows in rivers and allowable

abstractions to meet Ruaha goal

3)

The Problem: severe impacts on Ruaha National Park and failure of hydropower production

Area under rice (ha)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

1930 1940 1950 1960 1970 1980 1990 2000

Comparison of the dry season inflow to the Ihefu wetland and irrigated area

Since the mid-1990s, the Great in the Usangu catchment Ruaha River has ceased flowing in

180 1960

1970

1965 1990

1980 1985

1975

2000

y = -0.0029x + 153.75 1995

R2 = 0.7136 1999

the dry season every year because: 160

140 •water levels in the Usangu 120

wetland have dropped below a 100

80 critical level and outflows from the 60

40 wetland have ceased 20

•of diversions to rice irrigation 0

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 upstream of the wetland. Irrigated Area (ha)

Dry

season

Flo

w (M

m

Value of water across sectors Should water be allocated to the highest economic benefits or to secure the livelihood of the poor?

Paddy irrigation Hydropower

Water consumed (Mm3) 542 1,094 (4,096)

Net Real Value ($m-3) 0.04 0.21 (0.06)

If based simply on criteria of economic efficiency, water would be allocated away from irrigation to the downstream hydropower schemes.

Rice:

D 14-24% national paddy production

D 60% exported out of basin

D 30,000 households ($ 912/year)

Hydropower:

D 50% of national power (284

MW)

D Only 1% rural population

connected

Ultimately, water allocation is a difficult political choice

Wetland Hydrology

Wetland water levels P E

Storage Q

out

Qin

Water level at exit

NG’iriama exit

Great Ruaha

River

“Natural” annual water budget

Inflow: 3,390 Mm3

Rainfall: 490 Mm3

Evapotranspiration: 835 Mm3

Outflow: 3,045 Mm3

(78% of total input)

Human withdrawals from the rivers: 834 Mm

3

Environmental flow (Desktop Reserve

Annual environment flow: 635 Mm to

Model):

Mean annual flow: 2,933 Mm3

(93 m3 s

-1)

3

maintain the absolute basic ecological condition (21.6% of MAF)

Min dry season outflow: 0.5 m3s

-1

Min dry season inflow: 7.0 m3s

-1

The African Urban Challenges

D World’s most rapid rate of urbanization (~ 5% / year)

D African urban population will nearly quadruple (138 million in 1990 - 500 million in 2020)

D Several large African cities share at least one international river basin: the Nile, Niger, Congo, Limpopo, Volta and Zambezi.

D Growing water demand and discharge of wastewater from the cities pose a special challenge for river basins’ water resources management.

D Water authorities manage their water supply, sewerage and stormwater drainage systems as separate entities.

D Sharing of common water bodies by several African cities poses a special threat to freshwater quality and aquatic ecosystems (ex: Lake Victoria).

!( !( !(

!(

!(

Spatial context of urban water flows in Accra • Watershed Approach to

Urban WRM: manage both catchment (pollution control) and urban water cycle elements (water, wastewater, stormwater and water reuse) in an integrated way

Linking • Urban ~ Rural water management:

Agriculture ~ land treatment system and nutrient recycling part of the loop

• Domestic ~ Agricultural water use • Hydrologic Cycle /Water and

Nutrient Cycle

Volta Lake

Akosombo Dam

Kpong-Akuse Treatment Plant

Official urban boundary

Wejia Lake

Tanker waste Piped outflow Korle Lagoon disposal

Ocean

Treatment Plant in Accra

Wastewater disposal into Ocean

at ‘Lavendel Hill’

Water production at Weija

Wastewater reuse in Ghana

Addis Ababa (after Awulachew, 2006)

• Access to sanitary facilities: 74% • <10% provided with sewer system • Kaliti WSP treats <3.6%

• 11 unions with 957 households and 7450 family members

• 262 ha cultivated by the unions, 134 ha by the private

Water supply

Water reuse /disposal

(after van Rooijen)

Urban unit

Spatial context of urban water flows

• Water collection, storage, conveyance and treatment

• Flood protection

• Water supply, storage and distribution

• Sewage collection and treatment (MDG, EcoSan, etc.)

• (Waste)Water quantity & quality • Reuse for irrigation purposes and others

• Environmental services

Trade-offs EEccoonnoommiicc vvaalluuee ooff wwaatteerr aanndd EEnnvviirroonnmmeennttaall aanndd ppuubblliicc

nnuuttrriieennttss hheeaalltthh rriisskkss

D Conserves water and reduces freshwater demand

D Health risks for the irrigators and D Provides a reliable water supply communities in contact with

to farmers wastewater

D Low-cost method for disposal of D Health risks for the consumers of municipal wastewater vegetables irrigated with wastewater

D Reduces pollution of rivers, D Contamination of groundwater canals and other surface waters

D Build-up of chemical pollutants in D Conserves nutrients, reducing the soil

the need for artificial fertilizers D Creation of habitats for disease

D Increases crop yields vectors in peri-urban areas

D Has direct positive income effect for farmers

The Nile – an example of multi-national water management

D Unique in Africa for its long history, great technical complexity and its international scale.

D 15 bilateral treaties and agreements dated from 1891 to 1993 (Adams, 2001).

D The Nile Basin Initiative, established in 1999 with the support of the World Bank to facilitate cooperation among riparian countries.

D NBI’s Strategic Action Program: a basin wide Shared Vision Program and Subsidiary Action Programs (ENSAP, NELSAP)

Economic value of cooperation: status quo versus full cooperation

Milli

on

US

D

10000

8000

6000

4000

2000

0

Ethiopia

Sudan

Egypt

Others

Total

Status quo Full cooperation

Extra benefits of full cooperation is US$4.94 billion annually (Whittington et al., 2005).

Why multi-national water management is needed on the Blue Nile?

D Watershed degradation

D Flood damage along the Blue Nile in Sudan recently

estimated at USD 527 million for a 1-in-100-year flood

event (USD 52 million/year on average) (Cawood, 2005).

D Significant impacts of sedimentation:

D Loss of hydropower potential and of agricultural production

D Sediment load of the Blue Nile at El Diem of 140 million tons

per year (Ahmed, 2003)

D Management difficulties of irrigation canals networks in the

Gezira scheme: costs of the sediment clearance amounting

at more than 60% of the total O&M costs.

The Blue Nile – an example of multi-national water management

D A research project, aiming at improving water and land management in the Ethiopian highlands and its impact on downstream stakeholders dependent on the Blue Nile is underway.

D The work includes:

D hydrological and water allocation modeling

D watershed management

D policy and institutional studies at various levels

The Waters lems

hed Prob Causes

Impacts: Local

Impacts: DS

Sediment Volume and Content of Roseires Dam

- 0.02

- 0.032

- 0.043

- 0.051

Lake Tana

3,809 3,920

Bosheilo

2,072 Welaka

4,798 Jemma

4,389

North Gojam

2,440 Muger

2,187

Guder

1,719

Finchaa

5,012

South Gojam

2,355 Anger

5,673

Didessa

3,874

Wonbera

Flow gauging station

Reservoir

6,246

Dabus

4,345

Beles

2,797 Dinder

1,102 Rahad

Khartoum

Border

Roseires

Sennar

Kessie

Outlet Lake Tana

Giwasi

Hawata

SUDAN

ETHIOPIA

4,345 Mean annual discharge (Mm3)

Schematic showing proposed configuration of the water allocation model of the Blue Nile

1.40E+03

1.20E+03

1.00E+03

8.00E+02

6.00E+02

4.00E+02

2.00E+02

0.00E+00

Runoff

Flow (cms)

6.00E+04

5.00E+04

4.00E+04

3.00E+04

2.00E+04

1.00E+04

0.00E+00

Sediment Export (t/ha)

hrus1

SYLDtha

Sediment Yield

hrus1

SURQ_GENmm

0

0.001

0.306

0.307

0.308

0.309

0 - 0.003

0.003000000

0.020000000

0.032000000

0.043000000

Modeling the Gumera watershed runoff Schematization of Blue Nile for and sediment yield, preliminary results erosion and sediment modeling

CONCLUSIONS D IWM is about decision–making in a multiple-use and

multiple-user context to improve water productivity and derive optimum benefits for all relevant stakeholders.

D Different approaches are needed to address the critical development and management issues.

D Still a range of challenges:

D inter-sectoral competition for water

D dealing with trade-offs related to developmental and economic objectives, and equity and conservation considerations/between ecosystems

D integration across scales

D reconciling hydrological boundaries with administrative and political boundaries

CONCLUSIONS D Decision-making can be enhanced using tools that

promote stakeholder dialogue and take into account existing local-level traditional arrangements.

D In urban watersheds, comprehensive understanding of the entire urban water system is required. Innovations and investment interventions in technological, institutional change and sociological learning are needed.

D Transboundary coordination is needed to foster major win-win opportunities and overcome constraints to up­scaling promising management practices and technologies.

POLICY IMPLICATIONS D The adoption of the ecosystem approach will ensure watershed­

wide perspectives to development and management and make for social equity.

D The MUS concept in IWDM may provide the most equitable option on which watershed-wide plans may be based.

D Think more in terms of AWM rather than about irrigated or rainfed agriculture.

D Manage water, wastewater, non-point source pollution, and water reuse in an integrated way.

D In water allocation decisions, consideration of equity, food security, poverty reduction and development needs should be taken into account.

D Both watershed and administrative or social/cultural boundaries need to be considered.

D Nested institutional structures should be set up to manage us-ds interactions.

D Include informal small-scale water users.

D Adoption of a pragmatic mix of new and existing management arrangements to improve services and reduce conflicts.