This work describes the validation of a distributed model for estimating direct recharge and evapotranspiration over arid and semiarid regions. This validation was performed for a lysimeter-site planted to festuca (grown under controlled irrigated treatment) and for two months, June and July 2003. The model, which can be classified as a distributed water balance model, puts its emphasis on two devising aspects. First, a detailed description of the effect of the land use on the water balance through processes of evaporation/transpiration and the evolution in time of the vegetated surfaces on the area. Second, the operational character of the model. The model was conceived to run integrated into a Geographical Information System and incorporates the pre-processing of the needed input parameters. This pre-processing comprises the use of remote sensing observations to monitor the plants status and their dynamics. In this study, agrometeorogical station records and information on irrigation scheduling, soil hydraulic properties and the festuca culture were used to run the model, whereas lysimeter measurements were used as validation data. Moreover, the performance of the model was checked for contrasting water conditions of the soil: completely wet and dried out.