INCOH/SAR-23/2000-Conjuctive use of surface and ground water

Abstract

India having a geographical areas of 329 m.ha and supporting a population of one billion (2000) is a land of climatic contrasts. The season and weather conditions range from extreme cold to dry spell to extreme humidity and from drought conditions to torrential rains and floods. The rain takes place largely during the monsoon season, but of i.bout 1200 mm of annual average rainfall, 80% is recorded in four months from June to September and the remaining 20% during the winter months. If, for certain reasons, monsoon is too much late or if it is not evenly distributed over rainy season, or if the rainfall is to little or too much, then the whole agriculture sector is put in a tight corner. To ensure against the risk of vagaries of rainfall, irrigation has to be provided through systematic means. Rainfall has to be stored as much as possible, and the portion of it which percolates below ground has to be pumped out in a planned and scientific manner. Water flowing in the rivers the year round can also be diverted or lifted for irrigation. Thus, irrigation is provided by tanks, canals, wells and tube-wells. Each of these means of irrigation has its own role and uses in various regions of the country and it is well advised to develop in a planned and scientific manner the type of irrigation in a region for which it is most suited. It is only by developing assured and regular irrigation facilities so as to protect the country side from economic disasters and develop the agriculture which is the backbone of the ecnomy. Both surface and groundwater resources are being used for irrigation purposes. It is reported that by end of 1996-97, an irrigation potential of 89.44 m.ha. has been made available out of which 38.84 m.ha. is through Ground Water Development. Presently, however, ground water irrigation is contributing about 1.4 m.ha. of additional irrigation potential against 1.1 m.ha. from surface water. The Utilimate water resource avialble for irrigation is officially reported as 73 m.ha. for Surface Water and 40 m.ha. for Ground Water. However, Central Ground Water Board (CGWB) has tentatively revised the figure for ground water as 64 m.ha. (Refer "Ground Water Resource' of India" by CGWB 1995). The planning of two resources viz. surface and ground water is done separately and in an isolated way. The agency, organisation and implementation of two programmes is quite separate. However, inadequacy of irrigation water to meet the need of farmers in space and time has lead to large scale utilisation of ground water through wells and tube-wells in the command of irrigation projects. And so the conjuctive use becomes a necessity. Nevertheless some efforts have been made to utilise ground water in conjunction with surface water. This paper describes in detail the present status and gives recommendations for future for the conjuctive use of surface and ground waters.