6-Conjuctive Use of Surface and Groundwater in India.

Abstract

India having a geographical area of 329 m.ha and supporting a population of 845 million (1991) 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 about 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 too little or too much, then the whole agricultural 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 tubewells. 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 which can protect the country side from economic disasters and develop the agriculture being the backboneof the economy. Both surface and ground water resources are being used for irrigation purposes. It is expected that by end of 1989-90, an irrigation potential of 79 m.ha would be available out of which 34. 5 m.ha shall be through Ground Water Development Presently, however, ground water irrigation is contributing about 1.4 m.ha of additional irrigation potential against 12.1 m.ha from surface water. The ultimate water resource available for irrigation is officially reported as 73 m.ha for surface and 40m.ha for ground water. However, Central Ground Water Board (CGWB) has tentatively revised the figure for ground water as. 80 m.ha.