Impact of Climate Change on Streamflow Over Nagavali Basin, India

Natural disasters such as cyclones pose a serious threat to the Indian coast. The Nagavali basin is an interstate east-flowing river that supports agricultural and domestic water demands in Koraput, Kalahandi, and Rayagada districts in Odisha, as well as Vizianagaram and Srikakulam in Andhra Pradesh. Furthermore, this basin is especially prone to cyclones generated by low-pressure depressions in the Bay of Bengal. The present research aims to simulate the streamflow of the Nagavali basin using the SWAT model and to provide historical information as well as future changes within streamflow in response to climate change. Calibration (1991-2005) and validation (2006-2014) of the SWAT model showed a satisfactory for monthly streamflow. The downscaled bias-corrected geographically separated the NASA NEX-GDDP dataset was employed for simulating the future streamflow under two RCP scenarios, 4.5 and 8.5. The analysis periods were divided into 27-year blocks that included a historical period (1980-2005) as well as three future periods, namely near term (2022-2047), the middle future (2048-2073), and the far future (2074-2099). Under both scenarios, the CNRM-CM5 model predicted a rising trend in precipitation and streamflow. Under RCP 4.5, the CNRM-CM5 model showed the greatest percentage change of 22.06% in the far future, with a corresponding streamflow change of 36.26%. Under RCP 8.5, the BNU-ESM, CNRM-CM5, and IPSLCM5A-MR models represent percentage change in precipitation ranging from 22.09 to 26.28% and corresponding streamflow ranging from 33.81 to 45.11%, respectively, in the far future. Peak discharges are estimated at various return periods with Log Pearson Type III probability distribution. The estimated peak discharge (5626 m(3)/s) of the 100-year return period was observed in 2006. This study findings are useful to water resource managers.