In this work we show the GEA prototype (an environmental information manager) in order to assess water deficits over the irrigated crops of large areas. The proposed solution consists of evapotranspiration and water deficit estimations from remote sensing and agrometeorological information. The designed prototype is composed of three modules: (i) a geostatistical module, which generates precipitation and reference evapotranspiration maps from measurements collected in agrometeorological stations; (ii) an image processing module, which processes remote sensing images (Landsat) in order to derive canopy parameters and real evapotranspiration following the two-steps FAO method, where the crop coefficient is obtained from remote sensing data and an empirical relationship proposed by the Instituto de Desarrollo Regional IDR of the Universidad de Castilla-La Mancha; and (iii) a module which uses information technologies to develop the GEA on-line application, which allows the user to define regions of interest, real-time consulting of water deficits, elaboration of reports and image downloading, as well as a creation of a historical database or the configuration of alarms for situations of water stress. This prototype has been funded by the GESTA program of IMPIVA (Comunitat Valenciana) and FEDER funds.