Groundwater Flow Modeling of a Hard Rock Aquifer: Case Study

AbstractThe present study area is primarily underlain by granites, basalts, and a little bit of laterites. Groundwater occurs under unconfined to semiconfined conditions, in weathered and fractured formations, respectively. A three-dimensional groundwater flow model for the Osmansagar and Himayathsagar catchments—a semiarid hard rock area in India with two conceptual layers—is developed under transient conditions using visual MODFLOW software for the period 2005 to 2009. The 15–20 m top layer is a weathered zone, followed by second 20–25 m-layer fractured zone based on hydrogeophysical studies and borehole lithologs. The groundwater recharge estimation is achieved with the help of geographical information system (GIS) and the water table fluctuation method that is well fitted into the flow model with an average recharge value of 21% of the average annual rainfall. The results derived from modeling indicate that the average input to the aquifer system is 321.96 million cubic meters (mcm), and the output is...