Fresh water supplies management is a tough challenge in semi-arid and arid regions. The resources are limited and the demand is high. Agriculture is the major fresh water consumer and its usage should be carefully quantified. Agricultural activities span over large areas and can be monitored using remote sensing. It is necessary to implement models that can estimate ground level interactions using automatically acquired remote sensed data. This paper presents the modular implementation of the Mapping Evapotranspiration at High Resolution and with Internalized Calibration (METRIC, [1, 2]) model to create evapotranspiration (ET) maps. Agro-meteorological data obtained from TARBIL project's remote stations together with satellite images that incorporate thermal and multispectral bands are used as inputs to the model. The daily ET maps of large regions are obtained. The systems permits module modification with no change required on other modules.