Groundwater use for irrigation: lbli t a global inventory Jacob Burke Jacob Burke Senior Water Policy Officer Land and Water Division, Food and Agriculture Organization of the UN The Team The Team S Si b 1 S. Siebert 1 , J. Burke 2 , J.M. Faures 2 , K. Frenken 2 , J. Hoogeveen 2 , P. Döll 3 ,and F.T. Portmann 3 1 Institute of Crop Science and Resource Conservation, University of Bonn, Germany 2 Food and Agriculture Organization of the United Nations, Rome, Italy 3 Institute of Physical Geography, University of Frankfurt (Main), Germany Submitted for review to : Hydrology and Earth System Sciences Hydrology and Earth System Sciences http://www.hydrology-and-earth-system-sciences.net/home.html The Purpose The Purpose 1. To fill national and sub-national gaps in FAO AQUASTAT on the sources of freshwater that meet agricultural demand. the sources of freshwater that meet agricultural demand. 2. To establish the global extent of agriculture’s reliance upon groundwater sources for irrigation 3. To provide a standardized, digital product that can be used to assess current impacts of groundwater use in agriculture – a fi t f th FAO Gl b l M f I i ti A (GMIA) refinement of the FAO Global Map of Irrigation Areas (GMIA) (sub text: to get national agriculture/irrigation agencies to (sub-text: to get national agriculture/irrigation agencies to account for the groundwater they use and prick the collective conscience – e.g. lots of conjunctive use but little conjunctive management ) management.....) The Starting Point Percentage of 5 arc minute cell ( ~10km 2 at equator) equipped for irrigation - 1997-2002 data
Transcript
Groundwater use for irrigation:l b l i ta global inventory
Jacob BurkeJacob BurkeSenior Water Policy OfficerLand and Water Division, Food and Agriculture Organization of the UN
The TeamThe Team
S Si b 1S. Siebert1,
J. Burke2, J.M. Faures2, K. Frenken2, J. Hoogeveen2,, , , g ,
P. Döll3, and F.T. Portmann3
1 Institute of Crop Science and Resource Conservation, University of Bonn, Germany2 Food and Agriculture Organization of the United Nations, Rome, Italy3 Institute of Physical Geography, University of Frankfurt (Main), Germany
Submitted for review to :Hydrology and Earth System SciencesHydrology and Earth System Scienceshttp://www.hydrology-and-earth-system-sciences.net/home.html
The PurposeThe Purpose1. To fill national and sub-national gaps in FAO AQUASTAT on
the sources of freshwater that meet agricultural demand.the sources of freshwater that meet agricultural demand.
2. To establish the global extent of agriculture’s reliance upongroundwater sources for irrigation
3. To provide a standardized, digital product that can be used toassess current impacts of groundwater use in agriculture – a
fi t f th FAO Gl b l M f I i ti A (GMIA)refinement of the FAO Global Map of Irrigation Areas (GMIA)
(sub text: to get national agriculture/irrigation agencies to(sub-text: to get national agriculture/irrigation agencies toaccount for the groundwater they use and prick the collectiveconscience – e.g. lots of conjunctive use but little conjunctivemanagement )management.....)
The Starting Point
Percentage of 5 arc minute cell ( ~10km2 at equator)equipped for irrigation - 1997-2002 data
Some basic AQUASTAT definitions
Areas equipped for irrigation(AEI) area equipped with infrastructure to provide water to crops. It includes areas equipped for full/partial control irrigation, equipped lowland areas, and areasfull/partial control irrigation, equipped lowland areas, and areas equipped for spate irrigation.
Areas actually irrigated (AAI) –physical area that is irrigated and counted only once,
Area harvested and irrigated(AHI) area that is harvested in any one g ( ) yyear - a function of cropping calendars or cropping intensity and may be counted twice or thrice.
Consequently AAI is always smaller or equal to AEI and AHI.
Question: How much smaller would AAI be if it were not forQuestion: How much smaller would AAI be if it were not forgroundwater access in surface irrigation commands?
The Method• National and sub national statistical census data used: 203• National and sub-national statistical census data used: 203
countries and 15,038 administrative units analyzed.
R l li d t d t i if i i t d b ith f• Rules applied to determine if areas irrigated by either surfacewater, groundwater or non conventional sources (e.g.wastewater)
• National and sub-national data standardized to the extent possible
BUT…
• Only Pakistan and some European countries explicitly report conjunctive use
• AEI is reported in most cases as part of land use statistics while AAI is usually collected as part of water use surveys.
India: AAI_GW (% of total AAI) US: AAI_GW (% of total AAI)India: AAI_GW (index) US: AAI_GW (index)India: AAI_SW (index) US: AAI_SW (index)
Historical development of area actually irrigated with groundwater (AAI_GW) as percentage of total actually irrigated area, AAI_GW as index (2003 = 100), area actually irrigated with surface water (AAI_SW)as index (2003 = 100) for India and the United States of America (sources: agricultural census data).
Percentage of 5 arc minute cell equipped for irrigation and supplied by groundwater
Supplied by groundwaterSupplied by groundwater
Percentage of 5 arc minute cell equipped for irrigation and supplied by surface water
Supplied by groundwaterSupplied by groundwater Estimates of Groundwater Use in IrrigationEstimates of Groundwater Use in Irrigation
• Applying reference Et, cropping calendars, cropping factors to the updated GMIA through a global model (GCWM)
• Total crop water requirements can be estimated at 1 277 km3p q
• This compares with an estimate of 2 675 km3 for total agricultural withdrawals (global average ~ 50% water requirement ratio)
• Crop water requirements in groundwater sourced areas total 545 km3
(43% of total crop water requirements)( p q )
Question: Is groundwater irrigation always more precise and moreproductive than surface irrigation?
What does groundwater girrigation look like
th d?on the ground?
and from space… and from space
Can it be matched withCan it be matched with hydrogeological mapping?
Conclusions• There is no substitute for statistical data – data limitations
notwithstanding, still the only objective means of attributing areasequipped for groundwater irrigation at global level.
• Standardization of water source and water use data has to start at thefield collection level – a commonly accepted terminology is key.
• Groundwater dependency is growing and comes with a set of impactsGroundwater dependency is growing and comes with a set of impacts,many of which are irreversible - but at least we know where they will be.
Question: Can the patterns of demand be matched with the patterns ofQuestion: Can the patterns of demand be matched with the patterns ofgroundwater supply?
(will we get higher resolution digital mapping products?)
