SWAT based analysis of multiple GCM models for predicting the long-term effects on various hydrometeorological components of a dam-to-dam river basin

This study explored how the water balance components of the Middle Tapi Basin (MTB) might alter between 2010 and 2100 as an outcome of climate change. We used an approach were Statistically downscaled future predicted data for temperature and rainfall for five different Global circulation models were employed under two Representative Concentration Pathways (RCP 4.5 and RCP 8.5). The baseline and future scenarios’ monthly analyses of multiple water balance indicators also showed that RCP 4.5 and RCP 8.5 will see an increase in maximum temperature of 5.2% and 9.5%, respectively, by the end of the century. The baseline period contribution from monsoonal rainfall and streamflow was also 89.3% and 90.6%, but in future scenarios, the figures are likely to reduce to 75.2% and 57.8% for RCP 4.5 and 70.8% and 54.7% for RCP 8.5. While the average inflow estimates at the Ukai dam tend to rise by 19.2% and 46.8% till the distant future scenario for RCP 4.5 and RCP 8.5, respectively. In future scenarios, the percentage of groundwater flow and surface runoff contributions will be lesser due to the higher evapotranspiration rate and revaporisation of water to the root zone. Even though the monsoonal rainfall tends to reduce, the flow duration curves for the future scenarios exhibited a consistent increase in water availability compared to their respective historical counterparts, possibly due to more frequent and severe rainfall events.