This study aims to evaluate the reduction of evaporation of Lake Nasser’s water caused by disconnecting (fully or partially) some of its secondary channels (khors). This evaluation integrates remote sensing, Geographic Information System (GIS) techniques, aerodynamic principles, and Landsat7 ETM+ images. Three main procedures were carried out in this study; the first derived the surface temperature from Landsat thermal band; the second derived evaporation depth and approximate evaporation volume