MODELLING SURFACE RUN-OFF RESPONSE USING HYDROLOGICAL MODEL SWAT IN THE UPPER WATERSHED OF RIVER SUBARNAREKHA, INDIA

Abstract

Climate change is believed to affect the hydrological pattern of a watershed. The current paper evaluates the ability of a hydrological model Soil and Water assessment Tool (SWAT) to create a scenario of precipitation on the upper watershed of River Subarnarekha, Ranchi, in the state of Jharkhand, India. Sequential uncertainty fitting (SUFI-2) algorithm has been applied for model calibration and uncertainty analysis. The sensitivity analysis was made using a built-in SWAT sensitivity analysis tool that uses the Latin Hypercube One-factor-At-a-Time. The model parameters were calibrated (2001-2005) and validated (2013-2017) with discharge data obtained from CWC hydrological observatory site, Muri (Ranchi). In this study, IPCC SRES A1B Scenario, PRECIS RCM for time slices, near century (2011–2040, or 2020s), mid century (2041–2070, or 2050s) and end century (2071–2098, or 2080s) extracted by Indian Institute of Tropical Meteorology, Pune (India) have been used for the study The analysis shows that the mean annual rainfall will slightly decrease by 19.4 mm (1.4%) in the 2020s, increase by 86.2 mm (6.2%) in the 2050s, and further increase by 126 mm (9.1%) in the 2080s. For the 2020s, surface runoff shows an average annual decrease by 18.4%. For the 2050s and 2080s, there is an average annual increase by 11.8% and 38.2% respectively. It may be concluded that the precipitation pattern of the climate projections has a significant impact on water balance components. This study will be useful to take timely decisions for the best possible options to mitigate the impact of climate change.

Keywords

• swat
• climate change
• subarnarekha
• hydrologic model
• watershed
• jharkhand
• ranchi