Groundwater flow model of a typical hard rock granitic terrain- A case study from Osmania University campus, Hyderabad, India

The Deccan plateau region in Telangana that exposes the primordial Archean crust with semi-arid conditions, largely depends upon ground water. The study area, Osmania University (OU) campus, Hyderabad is spread over an area of about 29sq.km. of hard rock terrain, which consists of Archean granites, gneisses, intruded by dolerite dykes and frequented by lineaments revealing fractures, faults, joints and quartz veins. Generally in hard rock terrains, groundwater is confined to weathered and fractured layers due to negligible primary porosity however, secondary porosity simulates for groundwater flow. In the present study, a three dimensional groundwater flow model is developed using visual MODFLOW software to understand the present and future groundwater scenario based on geological, hydrogeological, and geophysical data that were acquired to construct the conceptual model. The results of the 3D groundwater flow model as obtained under steady state and transient conditions are compared with the field data. Sensitivity of the model was tested by altering parameters for the post monsoon period of 2014-2015 and the results have shown that post monsoon groundwater levels will fall more than 40m in the span of next 5 years, if the pumping continues at the current rate. Therefore, artificial recharge is suggested in order to increase the groundwater resources. Further, the results suggest that a reduction of 40% utilization of groundwater in the study area will increase the groundwater level in the future and may represents a base for groundwater yield that will aid groundwater management in the study area.