An assessment of future climatic and anthropogenic impacts on the hydrological system of a semi-arid catchment

Climate and catchment characteristics, particularly land and water use and management, may vary according to the population growth rate, future food habits and water demands. Three climate simulations corresponding to the Intergovernmental Panel on Climate Change, Special Report on Emissions Scenarios (A1B) were downscaled using the ‘Providing Regional Climates for Impact Studies’ (PRECIS) for the period 1961–2098, and bias correction was performed using the quantile mapping (QM) method. A semi-distributed integrated model (Modified Soil and Water Assessment Tool, SWAT) was used to predict the impacts of dynamic changes in catchment characteristics in the Himayat Sagar (HS) catchment and the effects of future climate change on future streamflow and groundwater storage. Simulations predicted that if this trend continues in the future, future climate and anthropogenic changes will lead to a more than 50% reduction in streamflow and a 50% increase in actual evaporation in the HS catchment. This would reduce groundwater storage to a depth of 15 m compared to current conditions, and by the end of the century, there would be no contribution from the base flow to the streamflow. Overall, unless current policies are modified to stabilize land and water management practices, anthropogenic changes will have greater importance than climate change.