Global Map of Irrigated Areas

Update for Asia

Version one of the digital global map of irrigated areas was mainly derived by combining large-scale maps with outlines of irrigated areas as described by Achtnich (1980) and FAOSTAT data on total irrigated area per country around 1995. For the update of the map for Asia, an inventory of sub-national irrigation statistics for the continent was compiled. The target year for the statistics is the year 2000.

The irrigated area per country as documented below adds up to 188 500 000 ha for the entire continent. The total number of sub-national units used in this inventory is 4 428. Sub-national irrigation statistics have been available for all countries except of Brunei Darussalam, East Timor, Georgia, Democratic People’s Republic of Korea and Qatar.

Although the incorporation of this inventory of sub-national irrigation statistics leads to a major improvement of the global irrigation map, uncertainties are still remaining mainly due to the use of different definitions for irrigated lands. In some countries there are only statistics available regarding actually irrigated area while other countries report the area equipped for irrigation. In some countries spate irrigation is included in the official statistics. It appears that in some countries statistics from different sources disagree on the area under irrigation lands. The indicators of uncertainty are mentioned in the documentation per country.

To distribute the irrigation statistics per sub-national unit digital spatial data layers and printed maps were used. Irrigation maps were derived from project reports, irrigation sub-sector studies or books related to irrigation and drainage. After on-screen digitizing of the maps the boundaries of the digitized irrigated areas were compared to satellite images in many regions. The shape and size of the digitized areas was adjusted thereby if necessary. Unfortunately for many sub-national units irrigation maps are not available. This occurs in particular in areas with low irrigation density dominated by small scale private schemes. Here additional information was used to find areas were irrigation is likely (e.g. land use maps which are showing where the main irrigated crops are growing). By assigning so priorities or weights to each digitized area it was possible to distribute irrigation statistics over digitized irrigated areas within the sub-national units. The methodology is described in detail in previous reports of the irrigation mapping project more (e.g. A Digital Global Map of Irrigated Areas - An Update for Latin America and Europe, Siebert and Döll, 2001). The map resolution during the generation process was 0.01 degree which was aggregated for the use on a global scale to a final resolution of 5 minutes (0.0833 degrees). The full documentation of this update is described by Stefan Siebert, Sebastian Feick and Jippe Hoogeveen in: "A digital global map of irrigated areas - An update for Asia" (2005). A summary per country is given below.

Choose a country from the list:

Afghanistan

The last available census-based inventory of irrigated areas dates back to the year 1967, giving a total of 2,385,290 ha. However, land cover maps, recently produced through the collaborative efforts of FAO, UNDP and the Afghan Geodesy & Cartography Office Kabul, indicate that the extent of irrigated areas hasn’t changed so much during the last 35 years. About 190,000 ha are classified as intensively irrigated (2 crops, rice-wheat), about 1,370,000 ha are classified to be cropped and irrigated at least once a year and about 1,650,000 ha are classified to be irrigated occasionally (every two or three years).

The area equipped for irrigation was computed for 329 district as the sum of areas classified as intensively or occasionally irrigated as indicated on the recently produced land cover map. The total area adds up to 3,199,070 ha. It should be noted, that the area actually irrigated may be significantly lower. Following statistics recently published by the Central Statistics Office (CSO), the extent of paddy cultivation has been 121,000 - 180,000 ha during the last ten years and the extent of wheat has been 1,600,000 - 2,050,000 ha respectively. About 46% of the harvested wheat area was irrigated in 2003. The distribution of irrigated area by sub-national unit is listed in this table.

Armenia

Area equipped for irrigation per district adds up to 286,027 ha on the country-level. The figures are related to the year 1992. The total area of irrigation schemes under construction was reported in the same document to be 27,341 ha. Two maps were used to distribute irrigated areas, the 12 major irrigation schemes were digitized from one map, since these large scale schemes were covering only 16 of the 39 districts of the country, irrigation schemes under construction and potential irrigable areas were digitized from another map. The distribution of irrigated area by sub-national unit is listed in this table.

Azerbaijan

The total area equipped for irrigation was reported to be 1,453,318 ha, which is about 90% of the arable land resources of the country. However, the area actually irrigated was about 1,100,000 ha during the cropping season of 2001. The irrigated area is distributed over five districts in Nakhichevan, the mainland of Azerbaijan is treated as one geo-graphical unit. Irrigated areas have been digitized from a map showing irrigation in the Caucasus-region. The boundaries of the digitized irrigated areas were adjusted by using recent satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Bahrain

The cultivated area in Bahrain increased between 1993 and 2000 from 3,160 ha to more than 4,000 ha and is completely equipped for irrigation. The irrigated area adds up to 4,060 ha and is documented for 9 regions. The figures refer to the year 2001. The location of irrigated areas could be detected by using a land use map showing the cultivated areas of the country. The irrigated areas were digitized in detail using Landsat satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Bangladesh

The area equipped for irrigation for Bangladesh is reported in AQUASTAT as 3,751,045 ha. The figures refer to the year 1995. However, for the year 1998 statistics are available on zila-level which add up to 3,360,265 ha. Most probably these statistics refer to the area actually irrigated and not to the area equipped for irrigation. Therefore it was decided to scale the irrigated area for the 64 zilas in such a way that the sum on the country level is consistent to the area reported as equipped for irrigation in the AQUASTAT-report. The location of the irrigated areas were derived from a map that showed irrigation as dots representing 1,000 acres of irrigated area. Using the map a distinction could be made between areas with high and low irrigation density within the zilas. The distribution of irrigated area by sub-national unit is listed in this table.

Bhutan

Irrigated area is reported to be 38,734 ha. The figures have been published in the year 1995 and have their origin from classification of satellite imagery (base year 1989-90) and ground truthing carried out in 1993-94. Irrigated areas are reported for 20 dzongkhags. The irrigated areas were digitized from a land use atlas at the scale 1 : 250,000. The distribution of irrigated area by sub-national unit is listed in this table.

Brunei

Irrigated area in Brunei was reported to be about 1,000 ha. The figures refer to the year 1995. No sub-national statistics were available. A map of irrigated areas was not available. Instead, cultivated area which is mainly located in the northern part of the country was digitized from satellite imagery.

Cambodia

In a recent inventory 802 irrigation systems in 15 provinces have been documented covering a total area of 282,072 ha. Of the schemes 125 schemes were reported not to be operational anymore and therefore their project area is not included in the given total area. The figures refer to the situation in 2001. The irrigated area of the six provinces not included in the inventory was reported to be about 2,100 ha in 1990. The total irrigated area of the country is thus estimated to be 284,172 ha. Digital maps as compiled by the Mekong River Commission showing irrigated areas (polygon data set) and irrigation projects (point data set) have been used. In general the point data set has been used in case of small schemes (below 300 ha) while the polygon data set has been used for large schemes (larger than 300 ha). Using these maps 278,000 ha of irrigated area could be located. The rest of the irrigated area was distributed to paddy areas taken from a digital land cover map. The distribution of irrigated area by sub-national unit is listed in this table.

China

The irrigated area reported on the basis of census results for the mainland of China was estimated to be 53,820,300 ha during the cropping season of 2000. The irrigated area for Hong Kong was estimated to be 2,000 ha. It should be noted that there are large uncertainties regarding the irrigated area in China. Inventories based on remote sensing report a much larger extent of areas under irrigation (the irrigated area for cropping season 1992/1993 for example was estimated at 78,000,000 ha). Irrigated area per county is available for the year 1990 and adds up to about 46,000,000 ha. The inventory is based on the agricultural census undertaken in the same year. In 1990 a 1 : 1,000,000 land use atlas was published based on satellite images and large-scale aerial photographs taken in the 1980’s. The irrigated areas and paddy areas derived from the land use map add up to about 68,000,000 ha. The large discrepancy between the results of the agricultural census and the results of land use mapping also appears for total cropland. In the census total cropland was reported to be 95,000,000 ha while the area derived from the land-use atlas adds up to 130,000,000 ha. From these discrepancies should be concluded that there are large uncertainties related to land use in China.

To estimate irrigated area per county during cropping season 2000 three inventories were combined. Irrigated area per province was assumed to be as reported by the Statistical Yearbook 2001 based on the census results. The downscaling to almost 3,000 county values has been done by combining the census results on the county level in 1990 and the irrigated area per county as taken from the land use atlas. The distribution of irrigated area per Province is listed in this table.

Cyprus

The extent of irrigable lands in the part of Cyprus under government control has been reported to be 45,452 ha in 2003, while the area actually irrigated was reported to be 35,931 ha. The irrigated area in the occupied northern part of the island was estimated by digitizing a land use map. The area equipped for irrigation for the entire island was estimated to be 55,813 ha. Eleven government schemes were digitized from a recent inventory. Additionally a large number of other irrigated areas were derived from a land use map produced in 1975. This map also shows irrigated areas outside the today’s government-controlled area. The distribution of irrigated area by sub-national unit is listed in this table.

East Timor

The total irrigated area of the country was estimated to be about 14,000 ha. The figures originate from a study of the Indonesian Ministry of Public Works and relate to the year 1990. There are no more recent statistics on a sub-national level available. No map of irrigated areas in East Timor could be found. Areas cultivated with paddy were derived from a digital 1:250,000 scale land cover map.

Georgia

During the Soviet period, infrastructure was built to irrigate 469,000 ha of agricultural land, mainly located in the more arid eastern part of the country. During the 1990s, civil strife, war, vandalism and theft, as well as problems associated with land reform, the transition to a market economy, and the loss of markets with traditional trading partners, contributed to a significant reduction of the irrigated area. It has been reported that during the severe drought in 2000 only about 160,000 ha were irrigated. Almost all pumping schemes (about 143,000 ha) were out of order. Therefore a rehabilitation program was started by the Georgia's State Department of Amelioration and Water Economy to renew the infrastructure of existing irrigation and drainage schemes and to establish Amelioration Service Cooperatives. About 255,000 ha are covered by these programs. Based on these reports the area equipped for irrigation in the Global Irrigation Map was reduced to 300,000 ha. Irrigation statistics in sub-national units were not available.

Irrigated areas have been digitized from an irrigation map published in a recent project report and from a map showing irrigated areas in the Caucasus-region.

India

For many (but not all) of the Federal States or Union Territories of India irrigation data on the district level were available. The data have been collected from various sources and refer to the so called ‘net area irrigated’, because the ‘area equipped for irrigation’ was not available. The term ‘net area irrigated’ means all areas that were irrigated at least once in the year of the reported statistics. It does for example not count for areas that were completely fallow during that year. Other terms commonly used like ‘irrigation potential created’ or ‘irrigation potential utilized’ could not be used because they are cumulative. They count for the potential created or used in all the years before the year of the statistics and may lead therefore to a double-counting of rehabilitated areas. The term ‘gross area irrigated’ which is also used in many statistical reports generally refers to the area harvested and leads therefore to double counting of areas that are cropped more than once.

Since the data are from different sources there are also different base years for the statistics. If data for more than one year have been available, the data closest to the year 2000 were used. The irrigated area of all the sub-national units in the different Federal States or Union Territories of India adds up to 57,286,407 ha.

The irrigated areas have been digitized from an irrigation atlas published in 1987 and from an irrigation map published in 1994. Both maps show the outlines of the large-scale irrigation schemes of the country and distinguish existing schemes, schemes under construction and proposed schemes. The location of minor irrigation schemes is presented in the irrigation atlas as dots whereby each dot represents 4,000 ha of irrigated area. The outlines of some schemes located in the state of Arunachal Pradesh were derived from a Chinese land use atlas. The outlines of the digitized irrigation schemes in the north-eastern part of the country (Arunachal Pradesh, Assam, Meghalaya, Mizoram, Manipur, Nagaland, Sikkim, Tripura) and in the north-western part of India (Jammu & Kashmir, Himachal Pradesh) were adjusted by using satellite imagery. The distribution of irrigated area per Federal State is listed in this table.

Indonesia

Irrigated area of 88 basins of the country adds up to 4,459,000 ha. The figures refer to the year 1990 but they are in agreement to the area equipped for irrigation as reported by the AQUASTAT-database for 1996 (4,427,922 ha). About 65% of the irrigated area is located on the island of Java. No actual map of irrigated areas in Indonesia is available. Instead a 1 : 2,500,000 land use map was used from which the rice fields were digitized. In some basins the area of digitized rice fields has been lower than the reported irrigated area. In those cases areas classified as lowland cultivation and highland cultivation were incorporated. Next to this paddy fields have been digitized from a second land use map. The distribution of irrigated area by sub-national unit is listed in this table.

Iran

Irrigated areas are reported for 25 'ostans' and add up to 6,913,800 ha . The figures refer to the year 1994, but since the data were published in the Statistical Yearbook of 2003, it can be assumed that more recent statistics are not available. The irrigated areas in the western part of the country have been digitized from a land use map published in the Tübinger Atlas of the Middle East. Since this map only covers the western part of the country, a large-scale land use map published in the same atlas and two large-scale irrigation maps, have been used the localize irrigated areas in the eastern part of Iran. Additionally satellite imagery has been used to find small irrigation schemes and to adjust the boundaries of the large schemes. The distribution of irrigated area by sub-national unit is listed in this table.

Iraq

The area equipped for irrigation is reported to be 3,525,000 ha in 1990. A large part of this area is not actually irrigated. Due to waterlogging and salinity the area irrigated in 1993 was only about 1,936,000 ha and decreased to 1,775,750 ha in 2001. It should be noted, that the three Kurdish provinces in the North of the country (Dahoak, Arbil, Sulaimania) are not included in these figures. The largest decrease of the area irrigated is to be found in the downstream provinces where agriculture completely depends on irrigation. In the provinces located more upstream of the Tigris River (Salah Eldin, Tameem, Nineweh), where also rainfed agriculture is practised, the actually irrigated area even increased between 1993 and 2001. No official statistics have been available for the mountainous, Kurdish Northern provinces. Therefore statistics originating from a land survey in 1992 and provided by the Kurdistan Democratic Party have been used for these provinces. Statistics of the area equipped for irrigation were not available on a province level. Therefore, the estimations of equipped area for the 18 provinces were made by combining areas from digitized land use maps, tactical pilot charts and satellite imagery with province-level statistics of the area actually irrigated in 1993 and 2001. The distribution of irrigated area by sub-national unit is listed in this table.

Israel

The irrigated area in Israel was at its maximum extent in the mid 1980’s at about 230,000 ha. It decreased to 186,600 ha in 2000. About 3,200 ha of irrigated area is located in enclosed settlements in the West Bank and Gaza territories, so the total area equipped for irrigation in Israel itself is 183,400. The irrigated area is calculated for 33 natural regions using statistics of cultivated crops, under the assumption that the area cultivated with flowers, gardens and citrus is completely irrigated, that 91.88% of the vegetable area is irrigated and that 74.08% of the other crops are irrigated. These coefficients were computed from inventories on the national scale. The irrigated areas have been digitized from two irrigation maps. The outlines of the digitized areas were adjusted by using satellite imagery. Some smaller irrigation schemes visible on the satellite images were also digitized and added to the map. The distribution of irrigated area by sub-national unit is listed in this table.

Japan

The area equipped for irrigation was available for the year 1993 for 10 provinces and adds up to 3,129,000 ha. In Japan paddy fields are almost completely irrigated, while only about 10% of the upland fields are irrigated. Additional statistics on the extent of paddy- and upland fields per prefecture have been used to estimate the irrigated area within the 47 prefectures. These figures are related to the year 1995. It was assumed that all the paddy field areas are irrigated and that the fraction of irrigated upland fields is constant for all prefectures within the same province. The irrigated areas have been digitized from an irrigation map sent to FAO with the AQUASTAT-country questionnaire. The distribution of irrigated area by sub-national unit is listed in this table.

Jordan

The area equipped for irrigation increased from 64,300 ha in 1990 to 76,912 ha in 2000. There are however uncertainties about this area since other inventories reported a total irrigated area of 84,130 ha in 1993 and 95,005 ha in 2000. The area equipped for irrigation is estimated for 8 governorates of Jordan. Irrigated areas were digitized by using an irrigation map of the Jordan valley and another map of irrigated areas outside of the Jordan valley. The boundaries of the irrigation schemes have been adjusted by using satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Kazakhstan

The area equipped for full control irrigation in Kazakhstan was 2,313,100 ha in 1993, apart from this there was about 138,700 ha of equipped wetland and inland valley bottoms. However, it has been estimated that during the cropping season 1994 about 680,000 ha of the land was out of use because of soil salinization, water logging, broken or incomplete distribution systems or other reasons. The values for the 19 'oblasts' add up to 1,855,200 ha and are distributed over the country by using a map of irrigation projects and two large-scale maps showing the outlines of the major irrigated areas of the country. Landsat-satellite imagery and a map of irrigation areas in the Aral Sea basin have been used to adjust the outlines of the irrigated areas. The distribution of irrigated area by sub-national unit is listed in this table.

Korea, Democratic people's republic

Irrigated area in the Democratic People’s Republic of Korea was reported to be 1,460,000 ha in 1995. There were no sub-national irrigation statistics available. There was no map of irrigated areas available for the Democratic People’s Republic of Korea. Instead, a recent geographic inventory of land form, land use and crop intensity has been used. The map is based on remote sensing and distinguishes the land forms: alluvial land, upland, hilly or steep land and wetland. The land use classes include: paddy rice, forest, rangeland or pasture and urban. It was assumed that the paddy rice fields (about 557,000 ha) are completely equipped for irrigation. It was furthermore assumed, that the fields assigned to other crops are also equipped for irrigation if they are located in the plains or river valleys with alluvial land (about 637,000 ha). The difference with the total area equipped for irrigation (about 266,000 ha) was distributed over fields cropped with upland crops.

Korea, Republic of

The irrigated area for 15 provinces adds up to 880,365 ha. The figures refer to an inventory of irrigated paddy during the cropping season of 2002. Apart from this, 258,043 ha of paddy are classified in the same inventory as ‘partially irrigated’. This area is not included in the area equipped for irrigation. The outlines of paddy areas have been digitized from a land utilization map provided by the Perry-Castañeda Library of the University of Texas. This map dates back to the year 1973, so the shape of the paddy areas was adjusted by using Landsat satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Kuwait

The cultivated area in Kuwait increased from 4,770 ha in 1994 to 6,968 ha in 2000. Because of the climatic conditions all the cultivated area is irrigated. The irrigated areas were digitized from Landsat satellite images and were in good agreement to areas shown as vegetated in recent maps for the 5 governorates as well as municipality maps. The distribution of irrigated area by sub-national unit is listed in this table.

Kyrgyzstan

In 1994, 1,075,040 ha was equipped for irrigation. Irrigated areas have been identified by using a map of irrigation projects and digitized by using satellite imagery and a map of irrigated areas. The distribution of irrigated area by sub-national unit is listed in this table.

Laos

Area equipped for irrigation has almost doubled in the period 1995 - 2000. Most of the increase is based on the establishment of pumping schemes which covered 46,150 ha in 1997 and 153,330 ha in 2000. The irrigated area for the 18 provinces adds up to 295,535 ha during the wet season, of which 197,100 ha is also used during the dry season. The Mekong River Commission compiled digital maps of irrigated areas (polygon data set) and irrigation projects (point data set). In general the point data set has been used to identify small schemes (below 300 ha) while the polygon data set has been used to identify the schemes larger than 300 ha, 265,000 ha of irrigated area could be located this way. The remaining 30,535 ha has been assigned to paddy areas as indicated on a digital land cover map. The distribution of irrigated area by sub-national unit is listed in this table.

Lebanon

The irrigated area for 26 'mohafazas' adds up to 117,113 ha which is about 40% of the cultivated area. The figures are related to the year 1997. The irrigated areas have been digitized from a land use map published in the Tübinger Atlas of the Middle East and from satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Macao

Total land area of Macao is about 2,680 ha of which 577 ha are classified as green area. The green area contains about 67 ha of gardens, parks and squares, 3 ha are classified as nurseries. However, no information has been available related to agricultural land use and irrigation. Therefore it was assumed that there isn’t any irrigated area in Macao.

Malaysia

According to AQUASTAT, the area equipped for irrigation was about 362,600 ha in the year 1994. Figures related to irrigated areas for the 14 states were available for the year 1993 and add up to 321,696 ha. The irrigated area per state has been scaled towards the value given by the AQUASTAT-report for the entire country. The boundaries of nine large government irrigation schemes, the so called granary schemes covering 196,284 ha, have been digitized from maps provided by the Department of Irrigation and Drainage. The remaining part of the irrigated area was assigned to a large number of small-scale irrigation schemes as digitized from another irrigation map. The distribution of irrigated area by sub-national unit is listed in this table.

Maldives

The cultivated area was estimated to be about 3,000 ha in 2000, but there is no irrigation of importance on the Maldives.

Mongolia

The area equipped for irrigation is about 57,300 ha, of which 43,400 ha were under highly mechanized sprinkler systems and about 13,900 ha were covered by surface irrigation systems. Of the total area equipped for sprinkler irrigation only 16,674 ha was operational in 1994. An inventory of the irrigated area for the 18 aimags (districts) of the country was available for the sprinkler irrigation schemes only. Most of the sprinkler-irrigated area is located in the West and the North of the country. About 80% of the surface irrigation schemes are located in the west. To estimate the total area equipped for irrigation, the statistics on sprinkler-irrigated area per aimag was scaled towards a total irrigated area of 57,300 ha. The location of 156 sprinkler irrigation schemes was derived from a recent inventory. The total area equipped for irrigation in these schemes has been reported to be 43,381 ha. Geographical coordinates of the schemes were missing in the inventory, but the name of the project and the name of the closest village were reported. The geographical coordinates of the villages have been detected by using the Geographical Names Server of the National Geospatial-Intelligence Agency's (NGA) and the related irrigated area was assigned to this location. The location of 13 schemes covering 2,060 ha could not be found this way. In addition the location of several unregistered schemes covering about 13,900 ha was unknown. To overcome this problem, cultivated land was digitized from satellite imagery and the irrigated area of the unregistered schemes, as well as the irrigated area of the sprinkler schemes with unknown position, was assigned to the digitized areas. The distribution of irrigated area by sub-national unit is listed in this table.

Myanmar

The irrigated area in Myanmar increased from about 1,000,000 ha during cropping season 1991/1992 to 1,841,320 ha during cropping season 1999/2000. Sub-national statistics were available for the cropping season 1994/1995. The irrigated area for the 14 states add up to 1,555,361 ha in 1995 and was scaled towards 1,841,320 ha as reported for the cropping season of 1999/2000. The location of 135 major irrigation works (dams, weirs, tanks) was digitized by using three maps showing irrigation works constructed in the periods before independence, between 1969 and 1988 and later than 1988. However, many projects are large and the irrigated fields may be located far away from the major reservoir or weir belonging to the project. Therefore additional maps have been used to locate the main irrigation areas of the country. It has been found that the location of known irrigated areas is in good agreement with the area classified as agricultural land in the GLC2000-land cover data set for South East Asia. Therefore this data set has been used to distribute the irrigated areas in regions outside of the main irrigation schemes. Since several irrigation schemes have been found in areas classified as ‘cultivated and managed, not irrigated (mixed)’ this land cover class was also considered as potentially irrigated. About 25% of the irrigated area of the sub-national units was distributed to this land cover class, while about 75% was assigned to areas classified as ‘cultivated and managed, irrigated (flooded, rice, shrimp farms)’. The distribution of irrigated area by sub-national unit is listed in this table.

Nepal

Area equipped for irrigation in Nepal is 1,168,349 ha. The figures are related to the cropping season of 2001/2002. The irrigated area is distributed over the 75 districts after digitizing irrigated areas from the GLC2000 land cover data set for South Asia. Areas classified as ‘irrigated intensive agriculture’ or ‘irrigated agriculture’ have been in good agreement to irrigated areas as shown on maps published in an irrigation master plan. Some additional projects were incorporated based on these plans and satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Oman

The irrigated area for the 8 regions of the country was available for the year 2001 and adds up to 72,630 ha. The cultivated area, which is completely irrigated in Oman, was digitized from Landsat satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Pakistan

The total area equipped for irrigation (including ‘full or partial control irrigation’ and ‘equipped wetland and inland valley bottoms’ but excluding spate irrigation) for the four Pakistani provinces is reported in AQUASTAT and adds up to 14,327,000 ha. The cultivated area in the autonomous districts of the Northern Territories along the borderline with India and China was assumed to be completely irrigated and adds to 90,464 ha. All figures have their origin in the agricultural census in 1990. The total area equipped for irrigation of the country is therefore 14,417,464 ha. The large-scale canal irrigated areas have been digitized from a map showing the irrigation infrastructure and the irrigated areas of the country. Satellite imagery has been used to incorporate the small scale schemes and to adjust the outlines of the digitized canal-irrigated areas. The distribution of irrigated area by sub-national unit is listed in this table.

Palestine

The irrigated area decreased from 17,247 ha in 1982 to 16,990 ha in 1990 and to 16,222 ha in 2001. Of the total irrigated area 6,990 ha was located in the West Bank and 9,220 ha was located in the Gaza Strip. Additionally 12.2 ha drip irrigation area was reported to be in Jerusalem. The irrigated areas have been digitized from a land use map published in the Tübinger Atlas of the Middle East, next to this satellite imagery was used to map more recently developed schemes. The distribution of irrigated area by sub-national unit is listed in this table.

Papua New Guinea

Area equipped for irrigation does not exist in Papua New Guinea. Some types of flood irrigation are reported but these types of irrigation do not meet the definition of full or partial equipped irrigation.

Philippines

The area equipped for irrigation for the 12 regions adds up to 1,550,000 ha. The figures are related to the year 1993. The area actually irrigated was reported to be 1,470,691 ha in the same year. The irrigated areas have been digitized from four different irrigation maps. The outlines of the irrigated areas were adjusted by using satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Qatar

The area equipped for irrigation was estimated to be 12,520 ha in 1993. The area actually irrigated during the year 2000 has been reported to be 9,762 ha. No statistics on the sub-national level were available. The location of the main irrigation schemes is shown on a land use map. The irrigated areas were digitized in detail from Landsat satellite imagery by using the land use map for verification purposes.

Russian Federation (in Asia)

The irrigated area for the 33 oblasts in the Asian part of the country adds up to 897,000 ha. The figures refer to the year 1997. Irrigated areas and arable land were derived from a land use map and from an agricultural map provided by the International Institute for Applied Systems Analysis (IIASA). In the Asian part of Russia only a relatively small area is classified as irrigated on the maps. This meant that some classes of arable land was also assumed irrigated in order to make sure that the irrigated area on the map was equal to the area in the statistics. The distribution of irrigated area by sub-national unit is listed in this table.

Saudi Arabia

The cultivable area in 2000 was estimated to be about 4,987,000 ha, of which only 1,119,750 ha was actually under cultivation. Another inventory states that 1,620,983 ha was under cultivation during the cropping season of 1992. All agriculture is irrigated and the extent of cultivation depends mainly on the availability of irrigation water. The area equipped for irrigation for the 13 regions, was estimated by using the maximum value of the cultivated areas for the cropping seasons 1992 and 2000. The so estimated irrigated area adds up to 1,730,767 ha. The irrigated areas were digitized by using Landsat satellite imagery, MODIS-Vegetation Indices and several large-scale irrigation maps. The approximate position and extent of the major irrigation schemes was based on the large-scale maps, while the more precise extent was derived by digitizing vegetated areas from satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Singapore

There is no indication that there is any irrigation of importance in Singapore.

Sri Lanka

The area equipped for irrigation in 1995 was about 570,000 ha. Areas equipped for irrigation were not available for the 26 districts. They were estimated by using an inventory of irrigated paddy fields during cropping season 2001/2002 and an inventory of other irrigated field crops during cropping season 1990/1991. The irrigated paddy area adds up to 335,026 ha in major schemes and 177,433 ha in minor schemes while the area of other irrigated crops was estimated at 61,351 ha. The total irrigated area adds up to 573,810 ha. The irrigated area per district was scaled in such a way that the sum of the irrigated area within the country meets the value of 570,000 ha as given by the AQUASTAT-report. The location of 308 major irrigation schemes (size > 40 ha) and 12 lift irrigation schemes covering 246,700 ha in total have been digitized from an irrigation map published in the National Atlas of Sri Lanka. The rest of the irrigated area was assigned to paddy areas as digitized from a land use map published in the same atlas, as well as from another map with a higher resolution but published in 1972, and from a map that was part of the Water Resources Development Plan 1976. The distribution of irrigated area by sub-national unit is listed in this table.

Syria

The irrigated area in Syria increased from 670,134 ha in 1989 to 1,088,891 ha in 1995 and to 1,266,900 ha in 2001. The irrigated area for the 13 governorates is assessed during growing season 2001. The irrigated areas have been digitized from an irrigation map covering the western part of the country and from two land use maps. Additionally satellite imagery has been used to locate recently developed schemes and to adjust the outlines of the digitized polygons. The distribution of irrigated area by sub-national unit is listed in this table.

Taiwan, Province of China

The irrigated area in Taiwan, Province of China, increased from 510,500 ha in 1990 to 525,528 ha in 1995. No statistics were available on the extent of irrigated area for the 23 counties. The irrigated area per county were estimated by using statistics related to irrigated area per region in 1995 and paddy area per county compared to other cultivated area per county in 1995. It was assumed that all the paddy area was irrigated and that the fraction of irrigated other fields was constant for all counties within the same region. Irrigated areas and paddy areas have been digitized from a 1 : 1,000,000 land use atlas. For the island of Penghu also satellite imagery was used. The distribution of irrigated area by sub-national unit is listed in this table.

Tajikistan

The area equipped for irrigation is estimated to be 719,200 ha. Of this area 240,200 ha is located in the Syr Darya River basin and 479,000 ha in the Amu Darya River basin. The figures relate to the year 1994. More recent reports indicate that there was no change until 2002. No sub-national statistics were available. The irrigated areas have been digitized from a map of irrigated areas in the Aral Sea basin. The shape of the boundaries of the irrigated areas was adjusted by using satellite imagery.

Thailand

Irrigation statistics were available for the 76 regions and add up to 4,985,708 ha. The figures refer to the year 2000. The Mekong River Commission compiled digital maps of irrigated areas (polygon data set) and irrigation projects (point data set) covering that part of the country which belongs to the Mekong river basin. In the other part of the country two similar data sets have been used. In general the point data set has been used to locate small schemes (below 1,000 ha) while the polygon data set has been used for larger schemes (over 1000 ha). Apart from this irrigated area was assigned to agricultural land as classified on a digital land cover map. The distribution of irrigated area by sub-national unit is listed in this table.

Turkey

According to AQUASTAT the area equipped for irrigation was 4,185,910 ha in 1994. The area actually irrigated has been 3,093,545 ha in 1991 and 3,143,000 ha in 1994. For the 73 provinces only data related to actually irrigated areas are available. The area equipped for irrigation has been estimated by choosing the maximum value of the areas reported as irrigated in the inventories 1991 and 1994. This way the total irrigated area adds up to 3,756,555 ha. The eventual irrigated area per province has been scaled proportially towards the 4,185,910 ha as reported in the AQUASTAT database. The irrigated areas have been digitized from a land use map published in the Tübinger Atlas of the Middle East and from a map showing the actual development status of the GAP-project in the south-eastern part of the country. Apart from this satellite imagery was used to locate irrigated areas developed after the publishing date of the maps in the Tübinger Atlas. The distribution of irrigated area by sub-national unit is listed in this table.

Turkmenistan

According to AQUASTAT the area equipped for irrigation was 1,744,100 ha in 1994. The total actual irrigated area for the 5 welayat during the year 1996 added up to 1,711,800 ha. The figures per welayat were scaled towards to the area equipped for irrigation as reported in the AQUASTAT-database. The irrigated areas have been digitized from a map with irrigated areas in the Aral Sea basin. The shape of the boundaries of the irrigated areas was adjusted by using satellite imagery. The location of the digitized irrigated areas is in good agreement to a map showing the irrigation infrastructure of the country. The distribution of irrigated area by sub-national unit is listed in this table.

United Arab Emirates

The cultivated area for the seven Emirates increased from 68,877 ha in 1992 to 111,356 ha in 1998 and to 280,341 ha in 2001 and is all irrigated. About 82% of the irrigated area is located in the Emirate of Abu Dhabi. The cultivated area of the country was digitized from Landsat satellite imagery. The digitized areas are in good agreement to areas classified as ‘agricultural areas and plantations’ in a recently published atlas. The distribution of irrigated area by sub-national unit is listed in this table.

Uzbekistan

Statistics on irrigated areas refer to 1996 and are available for the 13 oblasts. The irrigated area adds up to 4,223,000 ha for the whole country. The highest irrigation densities are in the oblasts of Andijon, Sirdarjo and Farghona where more than 50% of the area is equipped for irrigation. The irrigated areas have been digitized from a map with irrigated areas in the Aral Sea basin. The shape of the boundaries of the irrigated areas was adjusted by using satellite imagery. The distribution of irrigated area by sub-national unit is listed in this table.

Vietnam

The area equipped for irrigation in Vietnam is about 3,000,000 ha and refers to 1994. About 2,000,000 ha is actually used while about 1,000,000 ha is within the design command area but currently not being irrigated. Area harvested on irrigated fields is about 5,400,000 ha, which indicates a very high cropping intensity. The area equipped for irrigation for 31 districts, originates from an inventory of design capacities per district, from an inventory on irrigable land per basin and from an inventory of irrigated areas in the Mekong River basin. The Mekong River Commission compiled digital maps of irrigated areas (polygon data set) and irrigation projects (point data set) covering the (small) part of the country which belongs to the Mekong river basin. In the other part of the country irrigated areas have been distributed according to the GLC2000 land cover map to areas classified as ‘cultivated and managed, irrigated (flooded, rice, shrimp farms)’. The digitized areas are in good agreement to areas classified as irrigated on a large-scale irrigation map and maps that show the irrigation infrastructure of the country. The distribution of irrigated area by sub-national unit is listed in this table.

Yemen

The area equipped for irrigation was 388,000 ha in 1996. About 100,000 ha of spate irrigation is located in the governorates along the coast line (Taiz, Hodeidah, Laheg, Abyan, Shabwa, Haja and Hadramout). Actual irrigated areas are reported for the 19 governorates in 2001 and add up to 576,570 ha. These irrigated areas include spate irrigation areas which are not considered in the global irrigation map and therefore the total area was reduced by 100,000 ha. The remaining irrigated areas per governorates have been scaled proportially towards the 388,000 ha equipped for irrigation in 1996. The distribution of irrigated area by sub-national unit is listed in this table.