Groundwater flow modeling - A tool for water resources management in the khondalite and sandstone formations

Abstract

The groundwater levels in the non-command areas of East Godavari (E.G.) district of Andhra Pradesh State, India are gradually plummeting over the years. To estimate the impact of excessive use of groundwater and to suggest appropriate water management strategies, a regional groundwater flow model has been constructed for a watershed of 50 km2 namely ‘Kondakalava watershed’ (a non-command area) which is composed of khondalitic (in the northern part) and sandstones (in the southern part) formations. The groundwater flow model has revealed that the sandstone aquifer is experiencing huge aquifer stress due to heavy pumping rates, high well density, etc. If the present rate of pumping continued by 1% increase in every year, the sandstone aquifer is going to be dried in the future year 2036 by encountering the drawdown of 12 m whereas the khondalitic aquifer sustains with the minimum drawdown of 4 m without producing the dry cells up to the future year 2040. The higher recharge conditions and decreased pumping rates are helped for rising future groundwater levels by nearly 4 m in sandstone formation. Hence it is suggested that the runoff can be injected by deep tube wells in sandstone aquifer. The new ponds are to be constructed in order to improve the water table conditions of sandstone aquifer and the diversion of the water can be made from the newly proposed canal which is passing nearby watershed. In the watershed, two zones are identified to connect the existing ponds in order to improve the recharge conditions in the sandstone formation.