TN-5 : Water balance and interaction of large depression storage with aquifer in Ghaggar Basin

Abstract

Interaction of depression storage and aquifer till recently was either neglected or taken as a residual of a water balance study. Understanding of the interaction of surface water body with the aquifer is necessary in order to have a meaningful regional water balance study. Mathematical modelling has been found to be a potential tool to study this interaction.

In the eastern fringe of lower Ghaggar basin, there exist nineteen interconnected sand dune depressions in Suratgarh area of Sriganganagar district of Rajasthan which are used as flood cushion from 1968. The depressions have plan area to the tune of 100 sq. km. with storage capacity of 900 million cu. meters at full storage level. Due to the impoundment of water in the depressions, waterlogging in the isolated patches in the surrounding area has been first noticed since 1975.

In the present study, the recharge taking place from the depression storage to the aquifer has been assessed. A linear mathematical model has been developed using discrete Kernel generator and method of superposition to study the interaction between Suratgarh depression storage and aquifer. The discrete kernels for recharge hake been generated by making use of solution of Boussinesq's equation for unit step rise in the depression water level. The recharge quantity from the depression has been estimated for the drawdown in the depressions because of recharge. It is found that emptying of some of the Suratgarh depressions takes 7½ months after being filled-up