Desertification processes and impacts in irrigated regions

Desertification in irrigated regions is caused by man's activities but may be more rapid in periods of drought or abnormally high rainfall. It is caused by sedimentation of canals, use of poor quality water, or waterlogging or salinization because of rising groundwater tables caused by excessive applications of irrigation water. It can be avoided by good land management in catchments and irrigation areas but social, economic, and political factors cause difficulties. Direct costs due to loss of production from affected lands are less than indirect costs to national economies.