TR-18 : Assessment of recharge from various sources to an aquifer and assessment of aquifer yield

Abstract

With the increasing use of ground water for agricultural, municipal and industrial needs, the ground water development activity has increased considerably. Limited ground water resources demand scientific and economic planning for its optimum utilisation. Excessive draw downs without proper and planned utilisation may lead to adverse situations. In order to estimate the extent to which the ground water development should be carried out, a water balance study is necessary. To frame a ground water budget, two main factors viz. ground water recharge and ground water discharge, as input and output, are to be taken into consideration.

Rainfall forms the main source of ground water recharge. Of the total rainfall received, only a part percolates down to reach the ground water reservoir while a major part is lost through runoff, evaporation and transpiration. Besides the rainfall, seepage from the canal distribution system and deep percolation from the irrigated fields contribute substantially to the recharge to the aquifer. The recharge can be estimated by the quantification of various components that constitute the inflow and outflow into and from the ground water basin. These estimates provide information on the ground water potential and its availability which can be utilised for formulating the operational policies of the ground water extraction in an area.

A detailed review has been made on ground water recharge including both empirical formulae developed on the basis of water table fluctuations and experimental studies. Different methods of estimating recharge components are outlined and methodologies have been recommended to estimate the various components leading to ground water recharge to be adopted ill northern India with particular reference to alluvial plains.