Multi-site calibration of hydrological model and assessment of water balance in a semi-arid river basin of India

Abstract

Soil and Water Assessment Tool (SWAT) was calibrated and validated using multi-site streamflow data, and water balance was assessed in the Betwa river basin of central India. Sequential Uncertainty Fitting version-2 (SUFI-2) algorithm available in the SWAT-Calibration and Uncertainty Program (SWAT-CUP) was utilized for sensitivity analysis, calibration, validation and uncertainty analysis on the monthly time step. The model was calibrated for the period 2000–2005 and validated for the period 2006–2011 using data of four streamflow gauging stations. The values of P-factor and R-factor ranged from 0.51 to 0.75 and 0.17 to 0.53, respectively during calibration and validation periods. The values of Coefficient of determination (R2), NSE (Nash-Sutcliffe efficiency), RMSE-observations standard deviation ratio (RSR) and percent bias (PBIAS) varied from 0.83 to 0.92, 0.6 to 0.91, 0.3 to 0.63 and −19.8 to 19.3, respectively, for calibration and validation periods. Analysis of average annual water balance of Betwa river basin for the period 2000–2011 showed that out of the total annual rainfall of 878 mm, about 31% flows as surface runoff, 8% flows as baseflow and 61% is lost as evapotranspiration from the basin. The water yield from the basin constitutes about 37% of annual rainfall. The study revealed that basin is rainfed with most of the runoff (95.3%) occurring during monsoon season and therefore, the runoff occurring during monsoon season should be conserved by adopting suitable water conservation measures like farms ponds, check dams and percolation ponds so that stored water could be utilized during non-monsoon season.