Water scarcity demands precise knowledge of how water is used on the ground, yet most satellite models, including NASA’s PT-JPL, remain too coarse to guide fieldlevel decisions. We present a new approach that brings evapotranspiration monitoring to 10-meter resolution using Sentinel-2 satellite data. By integrating PT-JPL with an optical trapezoid concept, the method captures soil-moisture patterns that traditional models miss. Tested across 31 global sites in Morocco, the United States, and Australia, it consistently delivers more accurate and more detailed ET maps, opening the door to smarter irrigation, better drought response, and more modern water governance.