[A-HW33] Prediction of water and sediment dynamics from small to large scales

[AHW33-08] Change in Sediment Yield Dynamics in Bhagirathi Basin (Large Watershed) with Climatic Variables Having One Outlet by Using SWAT Model and SUFI-2 Algorithm.

*Jagriti jain¹, Deepak Khare¹ (1.Indian Institute of Technology, Roorkee)

Keywords:Sediment Yield, SWAT model, Climate Sensitivity , Large Watershed, One Outlet

In the present study, an attempt has been made to assess the impact of the climatic change on sediment yield in a hilly region of India (north of Tehri Garhwal district, Uttarakhand) by using Soil Water and Assessment Tool (SWAT). The study was conducted to determine the sediment yield using SWAT model Bhagirathi Basin, north of Tehri Garhwal district. The SWAT model is simulated from the year 1980-1993 with a warm-up period of 3 years on an annual basis. The sediment data is calibrated and validated with SWAT- CUP 2012 using SUFI-2 algorithm having R²= 0.43 and 0.54, NSE= -0.32 and -0.27 respectively. R² is set as the objective function for the analysis. From this study, it is found that the SWAT model has run perfectly well. From the result, it is conferred that the SWAT model does not cater to gully erosion, landslides and mass wasting, which are occurring in the region. There is also a lack of sites for the collection of data sample in a watershed of Tehri Garhwal as the sample collection is done at one outlet only. To determine the change in sediment yield dynamics with the climate, the climate sensitivity analysis is performed for the sediment yield in the study area with respect to perturbations in rainfall and temperature keeping other parameters constant. The change in sediment yield is decreasing when the rainfall is increasing and decreasing with the increase in rainfall. Maximum decreasing is seen when the smallest change in rainfall is observed with a value of 23.26 % when the rainfall is decreased by 5 % and the maximum increase is observed when the increase in rainfall is maximum with a value of 26.68 % when the rainfall is increased by 15%. The change in sediment yield is increasing when the temperature is increasing. The maximum increase in sediment yield is seen having a value of 42.10 % when the temperature is increased by 3⁰C from the baseline temperature.