Satellite-based monitoring of wheat crop consumptive water use

Evapotranspiration (ET) is the combined process of water loss to the atmosphere from the Earth's surface through evaporation from soil and water bodies, and transpiration from plants and vegetation. The accurate estimation of evapotranspiration (ET) plays a crucial role in optimizing agricultural water use and irrigation practices, especially in semi-arid regions with limited freshwater resources. This study aims to evaluate the performance of the Operational Simplified Surface Energy Balance (SSEBop) model in estimating the actual evapotranspiration (ETa) of wheat crops at the field scale in Tandojam, Sindh, Pakistan. The SSEBop model is a satellite-based energy balance approach that derives ETa by integrating remote sensing observations with ground-based meteorological data. In this study, 30 m resolution Landsat 8 and 9 imagery was utilized to map land surface parameters, while ancillary data from an on-field meteorological station provided inputs for computing reference evapotranspiration. The methodology involved preprocessing satellite data and computing vegetation indices, land surface temperature, and net radiation fluxes required by the SSEBop algorithm. Actual ET across different wheat growth stages (initial, mid, and late) was mapped for the study area. This research highlights the potential of the SSEBop approach for mapping ETa at field scales, which can inform sustainable irrigation management and water accounting practices for wheat cultivation in semi-arid regions like Pakistan.