Remote sensing-based estimates of evapotranspiration for managing scarce water resources in the Gezira scheme, Sudan

Water is a finite resource and rapid population growth in many and countries is putting excessive pressure on their limited water resources. Sudan has a large modern irrigated agriculture totaling more than 2 million hectares out of about 84 million that are potentially arable. The River Nile and its tributaries (18.5 km(3)/year) are the source of the water for 93% of irrigated agriculture. Gezira scheme is located in the central part of the Sudan. Its cultivated area estimated to be around 0.9 million hectares. The and climate and the low water use efficiency place more challenges for effective irrigation water management. Thus, spatial information of evapotranspiration (ET) is quite important to water resources managers. In this study remote sensing-based model was used to quantify the values of ET for different crops/vegetation on the surface. Surface Energy Balance Algorithm for Land (SEBAL) and Landsat images were used to identify water consumption on daily, monthly and seasonal basis. On the other hand, daily water required at different minor canals was calculated. For validation purpose, the daily and seasonal data were compared to the actual field data measured by soil water balance method. SEBAL results showed good agreement with the actual measurements.