Search

Groundwater flow modeling was carried out to assess current and to project future groundwater scenarios in highly populated and water stressed region of Ganges sub-basin. Both the urban and rural densely populated areas of Ganges sub-basin was selected to capture the groundwater usage patterns in these watersheds. The groundwater system geologically consists of sand and clay layers. However, the layers are not stratified and has highly variable thicknesses and at places various layers disappears. Therefore, a 3D model was prepared so that variability in the vertical direction is also taken care. The study area modeled is divided into grids with 37 rows and 37 columns with 1 km size. The month of June 2016 was taken to perform the steady-state simulation as June has the lowest groundwater levels as well as the minimum stress on the aquifer. Subsequently the Transient state calibration was carried out from June 2016 to November 2018. A good match is obtained between calculated and observed heads in steady state conditions after a rigorous calibration with RMS error as 1.822 m. The sensitivity analysis of the model shows that the model is more sensitive to input parameters like recharge and hydraulic conductivity. The prediction scenarios were developed for a period of 10 years from 2018 to 2028 using the local conditions of groundwater utilization as well as projected rainfall. The rise in water level in rural areas is observed resulting from artificial sources like canal recharge and irrigation return flows from irrigated lands. The rise in groundwater level is in the range of 0.13–0.31 m/year in Scenario I and 0.11–0.47 m/year in Scenario II. The decline in groundwater levels is noticed in urban areas which are a result of heavy domestic and industrial groundwater withdrawal and absence of recharge areas. The decline in groundwater level is in the range of 0.12–0.31 m/year in Scenario I and 0.24–0.33 m/year in Scenario II.