Estimation and Validation of Actual Evapotranspiration (ETa) of Maize Wheat Cropping System Using SSEBop Model Over IARI Research Farm, New Delhi, India

Evapotranspiration (ET) is an indispensable component of earth surface energy exchange studies and forms basis for various environmental applications. The present study attempts to estimate Landsat-8 satellite-based spatial distribution of crop ET using Operational Simplified Surface Energy Balance (SSEBop) model and validate through ET estimated using multilevel micrometeorological tower-based Bowen Ratio Energy Balance (BREB). The study was conducted over Indian Agricultural Research Institute farm during the summer (kharif maize) and winter (wheat) season of 2017–2018. The result of BREB showed the intra-seasonal variations in actual ET estimation ranging from maximum ET of 3.84 mm day−1 and 2.64 mm day−1 for maize and wheat during mid-stage to minimum ET of 1.88 mm day−1 for maize in maturity and 1.14 mm day−1 in an initial stage of wheat. It was observed that SSEBop slightly overestimated the crop ET; however, it showed the good agreement with BREB estimated ET (R2 = 0.76) with d-index of 0.92 and root-mean-square error of 0.48 mm day−1. It can be concluded that despite slight overestimation of ET by SSEBop, satellite-based SSEBop model can be recommended for crop ET estimation over large area and can be used for various water management studies.