Streamflow simulation using Soil and Water Assessment Tool (SWAT): application to Periyar River basin in India

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ABSTRACT

The present study investigated the ability of Soil and Water Assessment Tool (SWAT) in simulating streamflow of the Periyar River basin in India. The model was calibrated with six years of data (1990–1995), validated with three years (1996–1998) with 3 years warm-up period for monthly time steps. SWAT-CUP’s (Soil and Water Assessment Tool-Calibration and Uncertainty Program) algorithm, called Sequential Uncertainty Fitting 2 (SUFI-2), was employed for calibration and validation. The sensitivity analysis revealed that SCS runoff curve number (CN2) was the most dominant parameter affecting streamflow in the basin. The four statistical performance indices used in this study for calibration and validation showed ‘good’ performance of the model for the basin, with a coefficient of determination (R²) as 0.70 and 0.70; Nash-Sutcliffe Efficiency (NSE) as 0.70 and 0.68; Percent Bias (PBIAS) as 3.8 and −9.7; and the ratio of root mean square error to standard deviation of measured data (RSR) as 0.55 and 0.56, respectively. The results also showed that calibration with SUFI-2 algorithm could improve the model performance considerably. The water balance study shows that surface runoff contributes the highest with 41% of total water availability, followed by 28% actual evapotranspiration, and 24% percolation to shallow aquifers.

KEYWORDS:

• Streamflow
• hydrologic model
• soil and water assessment tool
• uncertainty
• Periyar River basin

Disclosure statement

No potential conflict of interest was reported by the authors.