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.