Crop management in a district within the Ebro River Basin using remote sensing techniques to estimate and map irrigation volumes

Abstract

An assessment of water management in the Flumen District, Central Valley of the Ebro River Basin in Spain, using the remote sensing technique Surface Energy Balance Algorithm for Land (SEBAL) was performed. This assessment was based on the estimation of the actual ET (ETa) to compute net water volumes (Vn). This work extended the analysis by also computing net irrigation volumes (Vi) by introducing a water application efficiency as a function of morphopedologic units (Eam). Two approaches were adopted for SEBAL Vi: a) the crop water demands including months outside the crop season (SEBAL_F1) and b) the crop water demands of the six main crops only in the growing season (SEBAL_F2). The comparison analyses for SEBAL_F1 and SEBAL_F2 Vi show a very good agreement with a bias of 0.09 hm3 and 0.56 hm3, respectively. As a result of an accurate estimation of Vi, the water use efficiency (Ea) for the whole Flumen District was determined to be from 80% to 90%. These are actual figures, thus it is possible to review the current crop and water management, identifying the possible causes for low irrigation efficiency on some plots.