| Abstrakt: |
This study assesses the response of hydrological processes to climate change in an Eastern Himalayan river basin using the SWAT model forced by high-resolution NEX-GDDP dataset. The SWAT model was set up to simulate streamflow under data-scarce scenario. Snow and elevation-related parameters for snow-dominated sub-basins were included during the model set-up to account for snow dynamics in the region. The model calibration and parametrisation as well as sensitivity analysis were performed using SWAT-CUP SUFI2 algorithm. Sensitivity analysis revealed that 19 parameters were sensitive for the region. The curve number (CN2) was determined to be the most sensitive parameter in the region, while the threshold depth in the shallow aquifer for return flow (GWQMN) was shown to be the least sensitive. Results showed a satisfactory estimate of daily streamflow for calibration (R2 = 0.88; NSE = 0.85; PBIAS = 1.02) and validation periods (R2 = 0.90; NSE = 0.84; PBIAS = –8.45). Uncertainty analysis during calibration (validation) resulted in p-factor value of 0.82 (0.90) and r-factor value of 0.87 (0.88), respectively. The ensemble of six RCMs under the NEX-GDDP dataset for precipitation and temperature was compared with the available observed data on a monthly time-step. The graphical comparison, as well as the performance indices, suggested that the NEX-GDDP dataset is capable of capturing the climatology of the region without bias. The NEX-GDDP dataset were divided into four different time periods, baseline period (1979–2005) and three future time slices, the 2030s (2019–2045), 2060s (2046–2072), and 2080s (2073–2099) under RCP 4.5 and RCP 8.5 scenarios. Under both RCP 4.5 and 8.5 scenarios, changes in average annual and seasonal precipitation (%), maximum and minimum temperatures (°C), streamflow, and other hydrological parameters were estimated for all future time slices (2020s, 2050s, and 2080s). The results of the climate change study estimated an increase in the average annual precipitation (+23.18%), maximum temperature (+2.4°C), minimum temperature (+2.64°C), streamflow (+31.62%), water yield (+31.81%), actual evapotranspiration (+6.37%), and groundwater flow (+33.41%), while soil water (–2.0%) was projected to decrease under RCP 4.5 scenario. In the case of RCP 8.5 scenario, the average annual precipitation, maximum temperature, minimum temperature, streamflow, water yield, actual evapotranspiration, and groundwater flow were projected to increase by 49.29%, 4.18°C, 4.23°C, 69.09%, 69.54%, 10.91%, and 65.15%, respectively, and soil water was projected to decrease by 4.52% by the end of the 21st century. The estimations prepared in this work will be useful for water resource planning and management under limited data conditions, hydropower developers, and decision makers and water policy specialists in devising future interventions in response to climate change projections. [ABSTRACT FROM AUTHOR] |
