Projected water availability in the Tawa River Basin India in changing climate

The Tawa River is one among the major southern tributary of the Narmada River in India, exhibiting substantial variation in rainfall, altering the water availability. The variation in water availability effect the hydrological characteristics such groundwater recharge, soil moisture level, water balance. Studying rainfall-runoff conversion is necessary for proper and sustainable surface and ground water resources planning and management. In the changing climate, it becomes imperative to understand the hydrological response and project water availability for sustainable water management. In this work, the MIKE 11 NAM model is calibrated and validated to evaluate the climate change impact on availability of water. Using the outputs of downscaled, bias-corrected data of CMIP6, the future projection of runoff is done for the near century, mid-century and end century under the scenario SSP245 and SSP 585. MPI-ESM1-2-HRand EC-EARTH 3-VEG climate models were selected. Temporal analysis was performed to evaluate the impact on the availability of water at the 50%, 75% and 90% percentage dependability flow. The annual analysis revealed that scenario SSP5-8.5 has a higher increase in the runoff than SSP2- 4.5, mainly for the end century, as depicted by both the models. Monthly analysis revealed strong intra-seasonal variations and highlighted that August is projected as the most active month of the year, and wet seasons displayed a larger change than dry seasons. The findings indicate that climate change shall significantly influence hydrological processes in the Tawa watershed and potentially impact the availability of water in the Tawa River basin. Our study underscores the imperative need to adapt water resource planning and management strategies to mitigate the potential impacts of climate change on the availability of water in the Tawa River basin.