Post on 24-Feb-2016
description
Growing Enough Food
Without Enough Water
David Molden
About IWMI
IWMI is one of 15 research centers supported by the Consultative Group on International Agricultural Research (CGIAR).
Mission: To improve the management of land and water resources for food, livelihoods and the environment.
Where we work:Headquarters: Colombo, Sri LankaIn Africa : Ghana, Southern Africa, EthiopiaIn Asia: India, Pakistan, Nepal, Laos, Vietnam, Central Asia, Syria
Water Scarcity 2000
1/3 of the world’s population live in basins that have to deal with water scarcity
Other Water Pressures
Population & Diet – food grain production projected to increase by 100% by 2050
Urbanization - Cities are projected to use 150% more water in 2025, encroach on ag land
Energy – Hydropower and biofuels compete for water and land
Climate Change – Shifting patterns of water availability
Drivers of Land & Water Use
Land degradation – limits productivityRiver basins closed – Colorado, Murray Darling, Yellow,
Indus, Amu Darya ……… 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
Some areas will be wetter, others drier, more rainfall variability, all hotter
Source: Arnell, 2003 – IWMI, FAO, ADB report on revitalizing irrigation.
Water Scarcity and Climate Change
Some areas wetter, some areas drier
Will there be enough water?
One liter of water produces one calorie on average
Food
Sup
ply
in C
alor
ies
One liter of water produces one calorie on average
USA
projectionsdata
2003
1961 2050
China
India
140
20
120
100
40
60
80
WorldMea
t con
sum
ptio
n kg
/cap
/yr
Per capita meat demand (kg/cap/yr)
More meat and milk requires more feed grain, requiring more water
More People – 6.5 to 9 billion people by 2050
More calories & more meat, fish, milk
More food production – need to double grain production by 2050
More water for food – if practices don’t change, double water needs
This equation doesn’t work – something has to change
Will there be enough water?
More people – 6.5 to 9 billion people by 2050More calories & more meat, fish, milk
More food production – need to double grain production by 2050
More water for food – if practices don’t change,
water needs for agriculture will double Something has to change
SolutionsOlivia Molden
Water Management
Major Pathways to Meet Future Food & Water Demands
1. Improve water productivity (more food/water)– Irrigation systems– Rainfed systems
2. Expand irrigated & rainfed agriculture3. Promote trade from highly productive to less
productive regions4. Manage demand, consume and waste less
Grow more food per unit of water
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7C
hish
tian
sub-
div.
Mah
i-Kad
ana
Nac
hcha
duw
a
Mud
a
Raj
anga
naya
Nile
Del
ta
Kou
rani
Bar
ia II
Sun
sari
Mor
ang
Gor
go
Wes
t Gan
dak
Mar
chw
ar L
ift
Sag
a
Big
Tho
mps
on
Kha
geri
Pan
chak
anya
Fryi
ngpa
n
Kan
kai
Mog
tedo
Sal
dana
Kou
rani
Bar
ia I
Sey
han
Coe
lla
RU
T
Torre
on
Sal
vatie
rra M
odul
e**
Alto
Rio
Ler
ma
*
Cor
taza
r Mod
ule*
Sal
vatie
rra M
odul
e*
Men
emen
Impe
rial I
D
Man
isa
Sam
aca
Triff
a S
chem
e, S
ec. 2
2
Alto
Rio
Ler
ma
**
Sar
igol
Pan
oche
WD
Ada
la
Bha
iraw
a Lu
mbi
ni
Ala
sehi
r
Turg
utlu
Cor
taza
r Mod
ule*
*
Sav
ili
US
dolla
r per
m3
Figure 4: Standardised Gross Value of Production per unit water consumed by ETcrop
* surface water and public wells ** private wells
Productivity of Water at 40 Irrigation Systems:
There is ample scope for improvement.
Source: Sakthivadivel et al, 1999
Range of water productivities in biological, economical and nutritional terms for selected commodities
aIncludes extensive systems without additional nutritional inputs to superintensive systems
Source: Muir, 1993; Verdegem, Bosma, and Vereth 2006; Renault and Wallender 2000; Oweis and Hachum 2003; Zwart and Bastiannsen 2004
Product
Water ProductivityKilograms per cubic meter ET
Dollars per cubic meter ET
Protein grams per m3
ET
Calories per m3 ET
Wheat ($0.2 per kilogram) 0.2-1.2 0.04-0.30 50-150 660-4,000
Rice ($0.31 per kilogram) 0.15-1.6 0.05-0.18 12-50 500-2,000
Maize (0.11 per kilogram) 0.30-2.00 0.03-0.22 30-200 1,000-
7,000
Beef ($3.0 per kilogram) 0.03-0.1 0.09-0.3 10-30 60-210
Fish (aquaculture)a 0.05-1.0 0.07-1.35 17-340 85-1,750
WP for Livestock and Fish• Beef 0.03 to 0.1 kg/m3 (ET)• Fish 0.05 to 1.0 kg/m3 (ET)Rapid increase in consumption of fish, meat, milk,
with incomeHuge scope for improvement – feed source, and
animal husbandry important
Reasons for Caution
Chishtian
Human
usesSurface
Rain
Groundwater miningEnvironmentalcommitments
Otherevaporation
VegetationCity uses
Crops
740km390%
Accounting for Water Use at Chistian, Pakistan
Often problem is overuse, not low efficiencyLow water productivity is the real waste
Breeding: optimism or caution?• Biophysical limit on biomass/transpiration• Harvest index already maximized – limit on
marketable produce per unit transpiration• Hard to foresee a big jump• except in underutilized, understudied cropsBut helpful in reducing damage from weeds,
insects, minimizing impacts of drought
Water productivity rises faster at lower yields and levels off at higher yields
Source: Adapted from Zwart and Bastiaanssen 2004In Water for Food, Water for Life, Earthscan Publishing
Water productivity is subject to diminishing returns
Source: Based on the yield-water productivity relationship for rainfed cereals in Rockström (2003)
In Water for Food, Water for Life, Earthscan Publishing
Area of Greatest Potential
Areas with high poverty
Opportunities in Rainfed Agriculture• Largest opportunities to build resilience and
improve water productivity are in rainfed landscapes – low productivity, high poverty
• Technology– water harvesting, supplemental irrigation– Field water conservation to reduce
nonproductive evaporation– Improved nutrients – Drought resistance varieties
• Expand “water” to includepolicies and practices forupgrading rainfed systems
Irrigation potential
developed:
Egypt, Morocco,
Somalia, South Africa > 75%
Botswana, Sudan,
Zimbabwe, Madagascar, Mali, Malawi,
Uganda 50-75%
Rest < 50%% Irrigated
LandINDIA:
~50SSA:
5
Rain = 1745 km3
Rainfed ET – 190 km3
Irrigated ET – 67 km3
Outflow – 10 to 30 km3
Limited options to expand irrigation – but gets attention
Ample options to upgrade agriculture on rainfed lands –gets little attention
A green-blue view
Irrigated
Pastoral
Rainfed
Wetlands
Consider A Range of Agricultural Water Management Options
Fish, Livestock, Crops, Ecosystem Services
Transforming Agricultural Water Management
We know what to do – we need to know HOW?
- Use of wells and dug-outs- Small-scale: labour-intensive manual
irrigation - Few commercial farmers : motor pumps- Irrigation during dry season
Crops: Mainly tomato, pepper, local vegetables
Shallow Groundwater Irrigation
• Millions of pumps in operation in S-Asia
• In India >70% of irrigated production
• High demand in SSA • Spontaneous uptake• Privately owned• Enormous impact on
farmer & landless income
But:• Small pumps are inefficient
(50%)• Still quite expensive sales
price and running• Technical knowledge gap• 6% GHG emission in India• Resource sustainability• No women ownership?
Solutions1. Affordable & efficient pump for
smallholders2. Alternative energy sources
(solar)3. Ban import tax on ag equipment
(cost of pump <$100 in India, $140 in Togo, $300 in Ghana). Zambia recently abolished
4. Extension training
Motorized pumps: extreme demand – extreme opportunity for change
Easy to transport: * individual* scattered plots* rent-out
Accra Market Queen
Making it Happen – beyond technologies
• Access to technology, seeds, fertilizers?• Is there enough money
or credit to buy them?• Are markets available to sell?• Financially viable?• Water and land resources available?• Is it sustainable – financial, ecological?• Supportive policies?• “Mind mobilization” Matsepo Khumbane
Summary – Water, Food & Livelihood Agenda
1. Enhance & safeguard water access for the poor
2. Increase water productivity 3. In doing so enhance ecosystem services &
resilience4. Transform water governance and
management
Water access, productivity,and ecosystems for livelihoods
1. Upgrade rainfed areas – manage water & soils2. Revitalize irrigation3. Sustainable groundwater management4. Reuse wastewater safely5. Transform water governance and management6. Support with information systems