Validation of SWAT model using satellite-derived evapotranspiration data

Efficient groundwater management through judicious irrigation scheduling can be accomplished by using the data of actual evapotranspiration (ETact), deep percolation loss (DPL) and surface runoff (SR). In data-scarce regions, the water budgeting approach using satellite-derived evapotranspiration can be an alternative approach to estimate different water balancing parameters. In the present study the operational simplified surface energy balance (SSEBop) model derived ETact data based on moderate resolution imaging spectroradiometer evapotranspiration (MODIS ET) fractions was used to calibrate and validate the SWAT model for five districts viz., Barnala, Sangrur, Moga, Patiala and Ludhiana of central Punjab, India. It was observed that coefficient of determination (R2) and the model efficiency of the calibrated and validated SWAT model varied from 0.65 to 0.75 and 0.50 to 0.60, respectively. Moreover, the district- wise AET values estimated by the validated SWAT model were 409.3 mm yr-1, 557.5 mm yr-1, 454 mm yr-1, 425.2 mm yr-1 and 548 mm yr-1 for Moga, Patiala, Sangrur, Barnala and Ludhiana, respectively. Further, the highest DPL rate estimated by the validated SWAT model was 9.6% of average rainfall for the Patiala district and other districts, it varied from 1.1% to 8.8%. Nonetheless, it was ascertained that the satellitederived evapotranspiration data can be successfully used for calibration and validation of SWAT model besides estimation of DPL and SR for efficient groundwater management at a regional scale.