HYDROLOGICAL MODELING OF BHAGIRATHI RIVER BASIN UP TO TEHRI DAM USING ARCSWAT

Abstract

Gaumukh Glacier is the origin of the Bhagirathi River, from there it flows about 193 km up to the Devprayag and merged with the Alaknanda river to form the River Ganga. The Bhagirathi river basin, a major river basin in Northern India and requires proactive management of water resources due to flood severity in this region. The Soil and Water Assessment Tool (ArcSWAT) was used in this study for setting up a watershed model for the simulation of streamflow in the basin. SWAT-CUP (SWAT-Calibration and Uncertainty Program) that allows calibration and global sensitivity analysis with the Sequential Uncertainty Fitting (SUFI-2) technique was used in this study. The SWAT model was calibrated from 2000–2010 with two years warm-up period (2000– 2001) and validated from 2011-2013. The feasibility of the model was reported based on R2 and NSE (Nash Sutcliffe efficiency). These parameters together indicate the strength of the calibration-uncertainty analysis of the SWAT model. During calibration, the R2 and NSE values were obtained as 0.87 and 0.83, respectively, while during validation, the R2 and NSE were found as 0.76 and 0.71. After the calibration and validation, global sensitivity analysis was done to find the most sensitive parameters of the basin. The result shows the CN2 (Curve number) was found most sensitive parameter. As per the statistical parameters of this study, the SWAT model can be efficiently used in the Bhagirathi river basin for managing droughts and floods, water management for agriculture, and planning for soil & water conservation structures.