Uncertainty in hydrological analysis using multi-GCM predictions and multi-parameters under RCP 2.6 and 8.5 scenarios in Manipur River basin, India

Climate change is likely to have adverse impacts on hydrological processes in a river basin, by altered runoff due to modifications in land use/land cover (LULC) and catchment hydrology. Substantial uncertainty exists to evaluate impacts of climate change on river catchment due to uncertainty in general circulation model (GCM) projections. In this study, impact of climate change on water balance and hydrological regime of Manipur River basin was investigated using SWAT model. A comprehensive semi-distributed soil and water assessment tool (SWAT) was used for future projection of changes in hydrological regime of Manipur River basin based on two representative concentration pathways (RCP 2.6 and RCP 8.5). A coupled model intercomparison project’s (CMIP5) based GCM downscaled outputs and future LULC projected data were used in the analysis. The projected temperature is likely to be increased by 2.84°C and increase of 836 mm in annual average precipitation is projected under RCP 8.5 by 2090s. Change in meteorological condition and LULC will lead to increase in runoff, evapotranspiration and water yield by 57.79 m 3 /s (38.32%), 318.7 mm (54.59%) and 629.72 mm (89.82%), respectively, by the end of 21st century. This study demonstrates the importance of water balance components and its spatial and temporal variation in the Manipur River basin. The key findings of this study reveals that the runoff, evapotranspiration and water yield will increase in the coming decades. Increase in water yield may lead to landslides in the hilly region and flooding in low lying areas in future. Highlights Both precipitation and temperature is likely to increase in Manipur River basin. There is high risk of floods in the lower regions near Loktak Lake and landslides in the northern part of the basin. There is no major concern with regard to water scarcity in the coming decades in Manipur River basin. There is good potential of hydro-power generation in the Manipur River basin because of increase in discharge especially during monsoon and post-monsoon season.