Estimation of evapotranspiration in lesser Himalayas using remote sensing based surface energy balance algorithm

In this study, remote sensing-based algorithm, METRIC is used to estimate evapotranspiration (ET) over a mountainous watershed in the lesser Himalayas in Uttarakhand, India. ET estimates of METRIC are compared with the ET values determined by using FAO Penman-Monteith equation and crop coefficients. In its original form, METRIC underestimated the ET values considerably with mean absolute error (MAE) of 0.95 mm/day. A modification is incorporated in METRIC for better representation of the effect of rainfall on the ET process. The proposed modification estimates ET at the hot pixel using daily rainfall and meteorological data. Using the modification, the MAE is reduced to 0.44 mm/day and underestimation of ET is reduced from 20.9% to 8.4%. This study contributes to the better understanding of ET in the lesser Himalayas of Uttarakhand. It also underlines the importance of accurate assignment of ET to the hot pixel for accurate estimation of ET using METRIC.

Automated summary

In this study, the remote sensing-based algorithm METRIC is used to estimate evapotranspiration (ET) in a mountainous watershed in Uttarakhand, India. The results are compared with values estimated using FAO Penman-Monteith equation and crop coefficients. The study finds that the original form of METRIC underestimates the ET values, but a modification to the algorithm significantly improves the accuracy.