Global Map of Irrigation Areas (GMIA)
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Philippines
Area equipped for irrigation was 1 879 084 ha in year 2006 [PH01]. To compute area equipped for irrigation at the province level, area equipped for irrigation in the National Irrigation System (NIS) and area equipped for irrigation in the Communal Irrigation system (CIS) was derived from an inventory provided by the National Irrigation Administration and related to year 2007 [PH02]. This inventory reported area equipped for irrigation of private schemes as well, but these data were related to year 1998. Therefore area equipped for irrigation in private schemes was computed as the difference between the total area equipped for irrigation in the National Irrigation System, the Communal Irrigation System and the Individual Irrigation System reported by the Agricultural Census 2002 [PH03] and area equipped for irrigation in the NIS and the CIS reported by the National Irrigation Administration for year 2006 [PH02]. The so computed difference was then scaled to fit to the total AEI reported in the AQUASTAT country questionnaire, resulting in an area equipped for irrigation of 721 040 ha in the NIS, 559 045 ha in the CIS and 598 639 ha in private schemes. The irrigated area per province estimated that way is visible in the table below and also can be downloaded as Philippines irrigation areas in PDF or Philippines irrigation areas in Excel.
Irrigated areas were digitized from a map provided by the Bureau of Soil and Water Management showing the extent of irrigated areas in the National Irrigation System (NIS) and the Communal Irrigation system (CIS) [PH04]. Since irrigated area in private schemes was not shown on this map, irrigated area related to private schemes was assigned to areas classified as cropland by the Globcover land cover classification [PH05].
In year 2006, 106 697 ha of the area equipped for irrigation was irrigated with groundwater, 1 477 703 ha with surface water and 294 684 ha with mixed surface and groundwater [PH01]. By assuming a groundwater contribution of 50% to areas irrigated with mixed sources, total area irrigated with groundwater was 254 039 ha or 14 percent of total area equipped for irrigation. While irrigation in the NIS and the CIS is predominantly from surface water resources (river diversion and reservoirs), private irrigation schemes are supplied also by pumping from aquifers and surface water bodies [PH01]. Therefore we assumed that in each province a constant fraction of 42.4 percent of the area equipped for irrigation in private schemes is irrigated with groundwater, while the area equipped for irrigation in the NIS and CIS schemes was assumed to be entirely irrigated with surface water. Because of the large harvested area of irrigated crops (2 695 825 ha in year 2006) it was assumed that area actually irrigated is similar to area equipped for irrigation.
References
[PH01]: FAO. 2013. AQUASTAT country profile of the Philippines, version 2011. FAO, Rome, http://www.fao.org/nr/water/aquastat/countries_regions/PHL/index.stm, 06/02/2013.
[PH02]: National Irrigation Administration. 2008. Status of irrigation development 2007. National Irrigation Administration, Manila, Philippines, http://region3.nia.gov.ph/upload_files/
file_22_2007StatusOfIrrigationDevelopment.xls, 09/03/2010.
[PH03]: National Statistics Office. 2004. Agriculture and fishery statistics. National Statistics Office of the Philippines, Manila, Philippines, http://www.census.gov.ph/data/sectordata/dataagri.html, 25/08/2009.
[PH04]: Bureau of Soil and Water Management. 2009. Irrigated areas of the Philippines. Map send to FAO in addition to the country questionnaire.
[PH05]: European Space Agency. 2010. GlobCover 2009 (Global Land Cover Map). http://due.esrin.esa.int/globcover/, 07/09/2012.
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