Assessing Evapotranspiration In Wheat Crop Using METRIC Model In Karnal District Of Haryana

Abstract

Sustainable agriculture requires efficient water management, particularly for water-intensive crops such as wheat. This study applies the METRIC (Mapping Evapotranspiration at High Resolution with Internalized Calibration) model to estimate actual evapotranspiration (ETa) in the wheat-growing regions of Karnal district, Haryana. A wheat crop mask was extracted and combined with satellite-derived indices (NDVI, SAVI, LST, LAI, and albedo), DEM, and meteorological data to compute surface energy fluxes and ETa. Field-based pan evaporation with crop coefficients (Kc) data was also used to estimate ETa for comparison. Results showed that pan-based ETa increased gradually with accordance to the growth stages of wheat and declined further. Validation against FAO Penman-Monteith Kc-based ETc showed moderate to strong agreement (R² = 0.68), with RMSE of 0.824 mm day⁻¹ and MAE of 0.609 mm day⁻¹. The METRIC model effectively captured temporal and spatial variation in wheat ETa across growth stages. Findings demonstrate METRIC’s reliability for water budgeting and irrigation scheduling, supporting precision agriculture and improved water productivity in semi-arid regions.