Spatial-Scale Sensitivity in SEBAL Evapotranspiration Estimation for Crop Health Monitoring with Sentinel-2A

The objective of this study is to apply Sentinel-2 satellite data for the monitoring of evapotranspiration of various crop cycles in Sillod, Maharashtra, India, including cotton, sugarcane, wheat, and maize. It uses a combination of some ET estimation methods, such as simplified ET and Priestley-Taylor methods, with net radiation (Rn) and sensible heat flux (H) calculations to estimate water extraction for each crop at four different times in June 2023 to February 2024. Some trends noticed here are that Rn was pretty consistent and high with fluctuating H values depending on the crop type or the growth stage. The minimum ET map values with the simple approach showed low minimum values for all study periods suggesting extensive water loss to ET processes. Spatial ET map variabilities were noticed with the Priestley-Taylor method, where it exhibited red and yellow color palettes that consider different crop water demands. To verify Sentinel-2-derived ET estimates, benchmarking using ERA5 evapotranspiration was calculated. The average ERA5 evaporation value from vegetation transpiration amounts to 1.21×10–10 in units of m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>/s, which compares well with the mean obtained from NDVI on Sentinel-2 equaling 0.1636. This cross-validation test makes sure our estimates of ET by Sentinel-2 are compatible with global datasets, which further supports the reliability and accuracy of the results derived. This study demonstrated strong effectiveness of a technique combining satellite-based ET estimation with remote sensing for the support of precision agriculture and sustainable water management. The findings are well-suited to provide valuable insights into optimizing crop water use in semi-arid regions, focusing on the potential of remote sensing for improving agricultural monitoring and resource planning.