M Senthilkumar

and 1 more

Chennai aquifer system covering an area of 6629 km2 is one of the most stressed aquifer systems in southern India as groundwater is relentlessly used for irrigation, domestic, industrial purposes and for drinking water supply to ever expanding Chennai city. This heavy extraction necessitated a paradigm shift towards groundwater management. Multidisplinary-integrated approach was taken up to map the aquifers, delineate its geometry, hydrodynamic characterization and to formulate an aquifer management plan through groundwater model. Weathered & fractures gneiss/charnockites along with alluvium form the aquifer units. Alluvium is the potential aquifer system of the region with potable quality except for the eastern/northeastern region affected by to seawater intrusion. Two-layered hydrogeological model was developed with one km2 grid pattern to simulate groundwater flow for nine years. The model calibrated under steady and transient conditions, allows quantifying the components of recharge, groundwater draft, and fluxes on the regional scale. Simulated results indicate that this aquifer system is under tremendous stress with the present groundwater withdrawal of 899 mcm and becomes unstable with 25 % increase in groundwater withdrawal by 2025. 54 mcm increase in resources due to recharge measures has groundwater head build up and easterly movement of the potential lines. Scenario of maintaining 120 days flow in rivers shows increase in groundwater head and development of the groundwater mounds, which are positive signatures for arresting the decline and pushing the saline water. Regulation of groundwater abstraction and rejuvenation flow in the rivers would sustainably manage the available groundwater resources of the region.