Hydromorphological analysis of Upper Tapi River Sub-basin, India, using QSWAT model

Morphometric parameters of a drainage basin are quantitative attributes of the landscape that are derived from the elevation surface and drainage network. The drainage characteristics of Upper Tapi River Sub-basin, India, were analysed by SRTM DEM using GIS tools, and the hydrologic parameters were calculated using QSWAT model. The QSWAT model was calibrated for the period 1991–2005 including 3-year warm-up period (1988–1990) with Sequential Uncertainty Fitting (SUFI-2) algorithm in SWAT Calibration and Uncertainty Program and validated for the period 2006–2013. The model performance is evaluated based on R2 (0.75), ENS (0.75) and PBIAS (1.1) values, which indicate very good agreement between observed and simulated discharge. The study area has been subdivided into 14 sub-watersheds, and 22 morphometric parameters have been calculated under three broad categories, viz. linear, aerial, and relief characteristics. The various morphometric and hydrologic parameters have been correlated with each other to understand their underlying relationship and control over the basin hydro-geomorphology. The R2 values for drainage density (Dd), sediment yield and evapotranspiration vary from 0.30 to 0.40. Similarly, the R2 values for stream frequency (Fs) and potential evapotranspiration, base flow, deep percolation, water yield were 0.93. 0.79, 0.75 and 0.81, respectively. The relationships among infiltration number (If), potential evapotranspiration, base flow, and sediment yield show the R2 values as 0.57, 0.48, and 0.70. Therefore, integration of morphometric parameters, GIS and QSWAT model have been done in this study to overcome the challenge of scarcity of observed data.