David MoldenInternational Water Management Institute

Climate Change and Agriculture: Building Resilience Through Better

Water Management in Southern Africa

One liter of water produces  one calorie on average

Food

 Sup

ply in Calories

One liter of water produces one calorie on average

Diets and water

Between 2,000 and 5,000 liters per person per  day –

depending on type and amount of food 

eaten and how it is produced

Other Water Pressures

Urbanization

‐

Cities are projected to use 150%  more water in 2025

Land Degradation

–

limits further productivity  increases

Climate Change –

Shifting patterns of water  availability –

potential yields decline in Africa

Energy –

Production and use by agriculture is in  competition with hydropower

Drivers of Water Use

How can water be developed and  managed to end poverty and hunger? 

A question posed to 700  researchers and 

practitioners who put  together the 

Comprehensive  Assessment of Water 

Management in  Agriculture.

Investing in Irrigation

Irrigated Area

Food price index

World Bank lending for irrigation

2.5

2.0

1.5

1.0

0.5

01960 1965 1970 1975 1980 1985 1990 1995 2000 2005

320

280

240

200

160

120

80

40

0

Living Planet Index Freshwater Species

Africa Irrigation

• River basins closed –

Colorado, Murray Darling,  Yellow, Indus, Amu Darya, Orange ‐

no additional 

water left

• Groundwater overdraft –

in agricultural  breadbaskets

• Fisheries – ocean and freshwater at a limit,  aquaculture will become more prevalent

• Livestock –

limit on extent of grazing land, more  will come from mixed and industrialized production

Limits –

reached or breached

Water Scarcity 2000

1/3 of the world’s population live in basins that have to deal with water scarcity

WHAT OF THE FUTURE?

USA

projectionsdata

20031961 2050

China

India

140

20

120

100

40

60

80

WorldMea

t co

nsum

ptio

n kg

/cap

/yr

Per Capita Meat Demand (kg/cap/yr)

Southern Africa

How much more cereals?

Food demand doubles over the next 50 years because of diet and population growth

Water Needs (ET) will double – without water productivity gains

Climate Change

Mitigation is about gases.

Adaptation is about water.

Climate Change in Africa According to IPCC  (2007)

Temperature and precipitation changes over Africa from the MMD‐A1B simulations. Top 

row: Annual mean, DJF and JJA temperature change between 1980 to

1999 and 2080 to 

2099, averaged over 21 models. Lower row: fractional change in precipitation. 

Variability in Precipitation

Thornton et al 2006

likely to increase with climate change

Observed Trends in River Flow

mean daily flow (annual averages) in Niamey (Niger)

0

200

400

600

800

1000

1200

1400

1600

1929

1933

1937

1941

1945

1949

1953

1957

1961

1965

1969

1973

1977

1981

1985

1989

year

[m3/

s]

Rainfall and GDP growthin Ethiopia and in SSA

Impact of rainfall variability on GDP and Agricultural GDP growth

-80

-60

-40

-20

0

20

40

60

80

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

year

%

-30-25-20

-15-10-50510

152025

rainfall variabilityGDP growthAg GDP growth

-6

-4

-2

0

2

4

6

8

10

12

1970

1975

1980

1985

1990

1995

2000

Annual growth rate

(%)

ag grow th GDP grow th

SSA GDP depends  on agriculture

Unmitigated Rainfall and Hydrological Variability Impacts Economic Growth and Stability

Water storage mitigates variability

Source: World Bank data from ICOLD

But need to re‐ think water 

storage: role of  groundwater and 

soil moisture. 

And beyond:  insurance, local 

trade

Cub

ic m

eter

s pe

r cap

ita

Water Storage Mitigates Climate Variability

4 43

746 12

87

1406 24

86 3255

4729

6150

01,0002,0003,0004,0005,0006,0007,000

Ken

ya

Eth

iopi

aS

outh

Afri

caTh

aila

nd

Laos

Chi

na

Bra

zil

Aus

tralia

Nor

thA

mer

ica

Cuvelai

Kunene

Zambezi

Limpopo

PunguéBuziSave-Runde

Orange Maputo

Incomati

Umbeluzi

Okavango/Makgadikgadi

Congo

Nile

Lake Chad

NamibiaBotswana

SouthAfrica

Congo (DRC)

Tanzania

Zambia

Zimbabwe

Lesotho

Swaziland

Malawi

Mozambique

Angola

250 5000

Kilometres

N

Rovuma

Thukela

South Africa (#11) and Zimbabwe (#20) are listed amongst the top twenty

countries in the world in terms of the numbers of

dams built (WCD 2000)

Sources: AQUASTAT Database (FAO, 2005); WCD, 2000

Large  Dams  in   Southern  Africa

N.B. Large dam: Wall height > 15 m and/or Volume > 2 million m3

(ICOLD, 1999)

• Africa has a total of 1,269 large dams; 827 (65%) of these are in the SADC countries

• SADC dams hold 37% of Africa’s impounded water

• South Africa (#11) and Zimbabwe (#20) are listed amongst the top twenty countries in the world in terms of the numbers of dams built

Policy Agenda –Where is there hope?

Around 70% of the  world’s under‐

nourished live in  rural areas where  non‐agricultural 

livelihood options  are limited.

Get water to poor people, use it better

Improve and Safeguard  Water Access

Access to Technologies

Consider A Range of Agricultural Water  Management Options

Fish, Livestock, Crops, Ecosystem Services

A range of options  Water sources in Krishna basin 

Krishna river basin

24 major reservoirs

6100 small reservoirs

High groundwater use

Adapt yesterday’s irrigation to tomorrow’s needs

1. To reduce rural poverty

2. To improve performance of many systems, 

3. To keep up with changing food demand

4. To adapt to changes – water scarcity, 

competition, climate change, energy5.

To increase multiple benefits and ecosystem 

services, while reducing negative impacts

Manage Water in Rainfed Landscapes

• Even if area irrigated doubles, the contribution to  food production for SSA from irrigation would 

change from 5 to 11%• Rainfed areas, especially in the semi‐arid tropics, 

have the highest potential for poverty reduction  and water productivity gains.

Upgrade Water Management in  Rainfed  Landscapes

The Small Reservoirs Project

Small Reservoirs

…. Half-moon with millet crop… Newly prepared half-moon at the inception of rain

…. Tied- ridges

Increase Water Productivity• Physical Water Productivity – more crop per 

drop– To reduce future water needs– For food production increases

• Economic Water Productivity – more value  per drop

– For more income, growth

– Integrated, multiple use systems

Productivity

United States

China

Latin 

America

Sub‐Saharan 

AfricaM

aize yield  (tons/hectare)

Importance of Fish and Livestock for Economic  Water Productivity

Make difficult choices  now, not later;

Try to increase the pie – share  the benefits

But difficult choices remain:

• Water storage for agriculture – water for environment

• Upstream – Downstream

• Productivity ‐

Equity

• This generation – the next one  (GW decline) 

Reform the policy reform  process

• Poverty, hunger, gender inequality,  and ecosystem degradation continue 

‐

not because of technical failings but  because of political and institutional 

failings 

Africa’s diversity is it’s wealth: • Diversity is a key to resilience• No blueprints ‐

need to craft local 

solutions

Thank You !

“Anyone who can solve the problems of water will be worthy of two Nobel Prizes – one for peace and one for science”

John F Kennedy