Spatio-temporal Estimation of Evapotranspiration and Runoff in Sub-Watersheds of a Basin Using ArcSWAT

Abstract

Evapotranspiration and surface runoff are hydrologic connections for overall water availability and water losses at basin scales. Estimation of evapotranspiration and surface runoff is a challenging task for water managers and researchers. Spatial and temporal changes occur in basin due to changes in physical topography and climatic conditions. It is very much required to model the basin to understand the behaviour and amount of water available in that basin at watershed and sub-watershed scales. The information at sub-watershed scale is vital for microlevel water-related planning in the basin for different water uses. In this work, ArcSWAT model is used to estimate evapotranspiration and surface runoff at sub-watershed scales. The study area in Indravati river basin comprises of 15 sub-watershed (WS1, WS2, WS3…WS15) which were divided into 199 hydrological response units (HRUs) that satisfactorily represent basin heterogeneity. Calibration and validation of SWAT model are done using Soil water assessment tool-Calibration and uncertainty program (SWAT-CUP) software with sequential uncertainty fitting-II (SUFI-II) algorithm. Results of this study show that the total average annual runoff and evapotranspiration (ET) are 94.85% and 4.56% of average annual precipitation (PPT), respectively. The sub-watershed WS8 receives maximum annual runoff and minimum annual ET as 98.43% and 4.43% of average annual PPT, respectively. Monthly variation of runoff and ET is also presented.