Paleochannel Recharge Sources in the Central Godavari Delta, A.P., India

The quality of groundwater in shallow alluvial aquifers exhibits wide range of variations, due to deltaic nature of the deposits, paleochannel and drainage conditions. In alluvial aquifers, the deeper aquifers are invariably saline. Demand for freshwater for drinking purposes in deltas is increasing day by day. Keeping in view such conditions, paleochannels contain and yield freshwater in significant quantities if they have hydraulic connection from the original river course from where they get recharged. One such major paleochannel of central Godavari delta has been identified by Andhra Pradesh State Ground Water Department during their investigations. The present paper deals with characterization of hydrochemistry in and around identified paleochannel spatially and temporally. The chemical analysis indicated that the electrical conductivity (EC) of paleochannel water is less than groundwater. Detailed hydrochemistry of canal water, drain water and river water is presented in the paper. The hydrochemistry of paleochannel water indicated that there is no significant seasonal change in paleochannel water, and most of the samples belong to Ca-HCO₃ type. The recharge to the paleochannel is studied by analysing stable isotopes (δ¹⁸O and δD) in groundwater, rainwater, canal water and river water. It is found that recharge to the paleochannel is mainly from river water and canal water than from rainwater. Optimum utilization planning of this limited freshwater resources in identified paleochannel is of immense importance, and it is also necessary to protect its quality from anthropogenic activities.