Water Harvesting for Improved Rainfed Agriculture in the Dry Environments

Abstract

In the arid and semi-arid regions, precipitation is generally lower than potential evaporation, non-uniform in distribution, resulting in frequent drought periods during the crop growing season, and usually comes in intense bursts, resulting in surface run-off and uncontrolled rill and gully erosion. In the cool winter areas, as in the Mediterranean type of climate, precipitation is less than 300 mm, part of which is lost to evaporation and run-off. The amount stored in the root zone is well below crop water requirements. In dry (semi-arid) tropical areas, such as the Sahel zone in Africa, although mean precipitation is relatively higher (500 mm), a larger portion of precipitation is lost to evaporation.