INCOH/SAR-3/95-Current status and prospects of rainwater harvesting

Abstract

Availability of water is a must for agricultural systems and assured irrigation is the principal requirement to stabilise and maintain agricultural production at a high level. With the prevailing monsoon type of rainfall, the arid and semi-arid regions suffer most for want of irrigation facilities. Even in high rainfall areas where irrigation facility does not exist, water deficiency periods do occur during critical crop growth stages causing low and uncertain yields. Though serious efforts have been made all over the world to cover more and more area under irrigation, a major portion of cultivated area still depends on rainfall. Inspite of all possible efforts the scope of irrigation expansion is limited due to various factors. At present only a small fraction of average annual rainfall is actually used for crop production in many rainfed areas. In such areas, efforts should be made to utilise maximum possible rain water by adopting water harvesting technol- ogy. Water harvesting was practised as early as 4500 B.C. in various parts of the world (Sastri et al., 1981). Water harvesting can be a soruce of water for variety of purposes in arid and semi-arid regions when common sources such as streams, springs or wells fail. In addition to supplying drinking water for people, live stock and wild life, water harvesting system can provide supplemental water for growing food and fibre crops. The term water harvesting was probably used first by Geddes (1963), who defined it as, "The collection and storage of any form of water, either runoff or creek flow for irrigation use". Myers (1974) modified this to "the practice of collecting water from an area treated, to increase runoff from rainfall and snow melt". Water harvesting is the practice of collecting water from an area treated to increase runoff from rainfall or snow melt for beneficial use (Boer et al., 1979). According to Tiwari (1984) water harvesting technology includes inducement of runoff from the land surface, collection and storage of runoff water in storage reservoirs or ponds, reducing the seepage and evaporation losses and use of the conserved water mast efficiently to provide life saving irrigation to crops.