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The map shows the fraction of each 5 arc min by 5 arc min cell area that is equipped for improved drainage at the end of the 20th century

Map description and dataset provided by: Institute of Physical Geography, University of Frankfurt (Main), Germany

DescriptionDrained Agricultural Areas

Artificial drainage decreases the average water content of the subsoil and accelerates the transport of water through the soil. Therefore, it influences nutrient transport by increasing leaching losses and by decreasing denitrification. The data set provides the fraction of surface area that is equipped with infrastructure to remove access water (e.g. ditches or drainage tubes). The map was developed by combining national statistics provided by international organizations (e.g. FAO, ICID, CEMAGREF), the “Global Croplands Dataset” (Ramankutty et al., 1998) and the “Digital Global Map of Irrigation Areas” (Siebert et al., 2005).


Artificial drainage is used to avoid water logging and to manage high groundwater tables. In semi-arid and arid regions, drainage of irrigated lands helps to reduce the risk of salinization and is thus, for many soils, a prerequisite for sustainable land use. In humid regions, drainage helps to extend the period in which the field can be entered with heavy machines. About 166.7 Mha of agricultural land is equipped for agricultural drainage at the global scale. According to the used statistics about 62.3 Mha of irrigated land and 82.7 Mha of rainfed land is equipped with artificial drainage facilities while for the remaining 21.7 Mha no distinction could be made. No data on agricultural drainage could be found for 120 countries. Most of them are very small so that their agricultural drainage area may be neglected in global assessments. However, there are also some larger countries (in particular in Africa) where it is known that artificially drained areas are existing but the extent of these areas is unknown (e.g. Mali, Niger, Chad, Mozambique). Therefore the real global extent of agricultural drainage may be underestimated in this inventory.


The dataset for this map was provided by: Stefan Siebert, Institute of Physical Geography, University of Frankfurt (Main), Germany


Artificial drainage – Infrastructure (e.g. ditches or drainage tubes) used to remove access water from agricultural land.


Please cite this map as: "GWSP Digital Water Atlas (2008). Map 70: Drained Agricultural Areas (V1.0). Available online at http://atlas.gwsp.org."

Contact Information

Stefan Siebert, Institute of Physical Geography, Georg Voigt Str. 14, 60325 Frankfurt (Main), Germany, This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , Phone: +49.69.798.25065, Fax: +49.69.798.25058

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