The increasing exploitation of ground water, especially in basins filled with unconsolidated alluvial deposits, has one of its consequences as the sinking or settlement of the land surface, known as ‘subsidence’. Though withdrawal of ground water has caused maximum subsidence of the order of 10 meters and these activities have seriously affected cities like Mexico, Venice and Bangkok, practically no data is available from India. The time is not far off when the problem of subsidence has to be taken up seriously in India and there will be an urgent need to develop a methodology to study the problem of subsidence. In this work an effort has been made in that direction.

Present study has been carried out to investigate the effect of pumping rate and number of deep tube wells on subsidence. An area in and around I. I. T. campus has been investigated under various discharge conditions from the existing and assumed deep tube wells. Detailed  analyses have been carried out by using a quasi three-dimensional model consisting of three-dimensional hydrologic model coupled with one dimensional consolidation model. Hydrological parameters representative of I. I. T. campus and surroundings have been used for the model simulation. The model however can be applied to any other area with a multi-layered aquifer system by simply changing the hydrological parameters appropriately. A numerical method of analysis based on finite difference technique has been employed for the analysis of quasi three-dimensional model. It has been found from the analysis that effect of discharge on subsidence is quite significant. A linear relationship between discharge and subsidence has been observed. An empirical relation is recommended for predicting subsidence for a given rate of discharge. The increase in number of tube wells does not affect the magnitude of subsidence significantly as long as the discharge is kept constant. Appreciable rate of subsidence for high discharge has been observed which should be incorporated in further planning of ground water exploitation.