Abstract
In order to asses water use in large areas, the most widely used method for estimating crops water
requirements is the FAO approach, which takes into account: i) climatic variables included in the reference
evapotranspiration and II) the crop type, characterized by the crop coefficient (Kc). In citrus trees, Kc is mostly functionof the tree ground covers (GC). In large areas, tree ground covers (GC) can be estimated by means of remote sensing tools, and once tree water needs are calculated, this information can be implemented in geographic information systems.
The present work summarizes some of the research conducted in order to determine citrus irrigation performance in a large irrigated area in Valencia, Spain. It is first described how tree ground covers (GC) can be obtained by using image analysis tools applied to multispectral images. Tree water needs are obtained and they are compared with the real water applications for a case study of a citrus water use association. The results obtained allowed to conclude that the tools developed might be useful for estimating water needs in large areas and improving irrigation efficiency showing some of the deficiencies currently found in irrigation management of collective water networks
