Abstract

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.

摘要

在这项研究中，基于遥感的算法 METRIC 用于估计印度北阿坎德邦小喜马拉雅山山区流域的蒸散量 (ET)。将 METRIC 的 ET 估计值与使用粮农组织 Penman-Monteith 方程和作物系数确定的 ET 值进行比较。在其原始形式中，METRIC 大大低估了 ET 值，平均绝对误差 (MAE) 为 0.95 毫米/天。在 METRIC 中进行了修改，以更好地表示降雨对 ET 过程的影响。建议的修改使用每日降雨量和气象数据估计热像元处的 ET。使用修改后，MAE 降低到 0.44 毫米/天，对 ET 的低估从 20.9% 降低到 8.4%。这项研究有助于更好地了解北阿坎德邦较小喜马拉雅山脉的 ET。