Abstract:
Water occuring in the subsurface was known tomankind before the beginning of the christian era. As the demand is increasing due to increase in agriculture areas and the improve-ment in the agriculture practice more and more water is being used. Surface sources are not capable to meet the demand round the year in such a large scale. Hence groundwater sources are being exploited more and more. With the increase in the exploi-tation of ground water sources a quantitative assessment of the available sources in time and space within the subsurface has become as must. In India this aspect was realised and first attempt to know the precise hydrological parameter of aquifer in Gangetic plains was initiated in 1931. Upto 1967 availability of ground water resources has been followed by some empirical approach. In 1967 first water balance study was done for the and tracts of Rajasthan. This is lumped nodel which gives only overall assessment of water in a region. Distributed model is to indicate the assessment of water in time and space and is done with mathematical model.
