groundwater use and depletion in asia:implications for irrigated agriculture
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Groundwater Use and Depletion in AsiaImplications for Irrigated Agriculture
Tingju Zhu
International Food Policy Research InstituteWashington, DC
Water Policy for Food Security: A Global Conference, Davis, CA, October 5-6 at UC Davis
The world's most populous continent, with 4.4 billion population in 2014
Accounting for 70 percent of the world’s net irrigated area
With 20 million wells, South Asia alone accounts for nearly half of global groundwater used for irrigation
Asia is responsible for the largest share of food production from depleting groundwater, especially in northwestern India and North China Plain
High vulnerability to climate change – Glacier-fed rivers and major river deltas critical for agriculture are to be affected
Growing population and changing to more water-intensive diet
Asia – Population, Water, and Agriculture
Hydro-climatology, Irrigation, and Irrigated Areas
Source: 1) Precipitation from GPCC v5. 2) PET and runoff simulated by the IMPACT Global Hydrological Model (IGHM) for 1971-2000. 3) Irrigated area share based on GMIA database by Siebert et al. (2007).
• IGP• NCP• Deltas
78
80
82
84
86
88
90
1000
1200
1400
1600
1800
2000
2200
2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055
Asia - Irrigation consumption World - Irrigation consumptionAsia - Share of irrigation water consumption World - Share of irrigation water consumption
Irrigation Water Consumption and Share in Total Water Consumption – Asia and World
Source: IMPACT3.2 baseline projectionNotes: Consumption in km3/yr
0
200
400
600
800
1000
1200
2000 2030 2050
Cons
umpti
ve U
se in
Irrig
ation
(km
3 /yr
)
Other
Vegetables
Cotton
Maize
Sugarcane
Wheat
Rice
Irrigation Water Consumption by Crop in Asia
Source: IMPACT model projections in IFPRI report submitted to ADB (2013)
0
50
100
150
200
250
2000 2030 2050
Cons
umpti
ve U
se in
Irrig
ation
(km
3 /yr
)
Other
Soybean
Cotton
Vegetables
Maize
Wheat
Rice
0
50
100
150
200
250
300
350
400
450
500
2000 2030 2050
Cons
umpti
ve U
se in
Irrig
ation
(km
3 /yr
)
Other
Sub-tropicalfruitCotton
Sugarcane
Rice
Wheat
China India
Irrigation Water Consumption by Crop in China and India
Source: IMPACT model projections in IFPRI report submitted to ADB (2013)
Groundwater Irrigated area in Asia
Source: Irrigated area share based on GMIA database by Siebert et al. (2007).
Groundwater Withdrawal in Asia: 1940-2010
Source: Shah et al. (2007)
Groundwater Abstraction by Region and Crop
Australia/Oceania
0%
Central Asia2%
East Asia14% Latin America
and the Caribbean
2%
Near East/North Africa16%
OECD23%
Other European Countries
1%
South Asia41%
Sub-Saharan Africa
1%Regions
Beverage and spice crops
19%
Cereals43%Leguminous
crops4%
NonFood Crops
9%
Oilseed Crop8%
Other Crops0%
Roots and Tubers
2% Sugar Crops
7%
Vegetables and Fruits
8%
Crop Groups
Source: IWMI and IFPRI analysis, work in progress
Groundwater Depletion by Region and Crop
Australia/Oceania
0%
Central Asia2%
East Asia10%
Latin America and the
Caribbean1%
Near East/North Africa23%
OECD24%Other European
Countries1%
South Asia38%
Sub-Saharan Africa
1%
Regions
Beverage and spice crops
11%
Cereals49%
Leguminous crops
4%
NonFood Crops12%
Oilseed Crop7%
Other Crops
0%
Roots and Tubers
2%
Sugar Crops6%
Vegetables and Fruits
9%
Crop Groups
Source: IWMI and IFPRI analysis, work in progress
Groundwater Depletion in Indus and Ganges Basins (GRACE and Reconstructed Depletion in Dry Season)
Oct-Apr
Oct-Apr
Source: IFPRI and UCF, work in progress
Drought Frequency in the Indus and Ganges and Reconstructed Precipitation
Drought frequency (as a percentage) during the Period of 1300-1899 (left) and 1900-2010 (right)
Indus basin Ganges basin
Source: IFPRI and UCF, in Davtalab et al. (2015)
Source: Gao et al. (2013)
Groundwater Depletion in North China Plain
Groundwater Management in the Indo-Gangetic Plains
Bihar
Western IGP:• High investment in
infrastructure; • Effective institutions and policy
support• Intensive agriculture (e.g.
agrochemicals and ground-water irrigation)
• Surplus food production responsible for regional food security
• Seasonal in-migration of male labor
Eastern IGP: • Relatively low productivity and poor infrastructure• Limited capacity for private investment • Prone to flooding and drought• Food deficit region; out-migration of male labor to other
regions
Food-Water-Energy NexusEnergy Subsidies
Groundwater development challenges
Groundwater irrigation Challenges in Eastern IGP
(Vaishali, Bihar)• Irrigation in Vaishali almost entirely depends on
groundwater; surface water irrigation infrastructure existing but not functional
• Bihar is an electricity-scarce state; irrigation in Vaishali has to rely on diesel pumps
• Diesel price is high (~Rs52/l; new pump set Rs25K~30K)
• Ownership of tubewells and pump sets
• Farmers have little capacity in private investment• Farmers indicate delayed Monsoon can cause ~80%
production cost increase (rice + wheat)
Additional Irrigation for Crop Intensification in China?
Source: IFPRI and CAAS, work in progress by Yu et al.
Irrigation water use in China remains roughly unchanged for more than two decades.
South-to-North Water Transfer Project’s water too expensive for agriculture.
Investment in rural water infrastructure has been increased since 2011.
Pilot sites for market-based water transfers in 7 provinces, by MWR.
Is water-saving irrigation technologies a solution?
Lack of Incentives: Farmers concern economic return and production risks, not necessarily irrigation water-saving
Technologies need to be adapted to local settings
Technologies need to go hand in hand with agricultural extension
Move from water-saving to cost-effectiveness, including labor-saving, energy-saving, higher yield and better crop quality, and reduced production risks
Information and institutional development
Adoption of Irrigation Technologies for Water-saving in Asia
Conclusions
Groundwater is critical for agricultural production in Asia, with increasing withdrawal trends in many countries.
Depletion of groundwater is a growing challenge to sustainable water use and agricultural production, especially in northwestern India and North China Plain.
Groundwater will become only more important in the future, with decreasing snowpack (i.e. Himalayas rivers) and increasing hydroclimatic variability.
Enhanced monitoring, assessment, and holistic multisector policies are critical for sustainable groundwater use and irrigation in Asia.