ET Tool has evolved from the successful SEBAL model created by Waterwatch. While SEBAL is unprecedented in its accuracy and high resolution results for river basin studies and crop growth monitoring studies, it was not particularly designed to model large areas. ET Tool produces the same outputs as SEBAL but will do this for large areas, even up to continental scale.
ET Tool output is quantitative at discrete space intervals of varied sizes which provides quantitative shortages (mm) due to anomalies in soil moisture, vegetation cover, meteorology and groundwater levels. Output parameters are (among others) actual and potential transpiration, transpiration deficit and biomass production. In contrast to SEBAL, ET Tool is not affected by cloud cover in the satellite imagery. ET Tool’s highest temporal resolution is daily, which allows it to be used on an operational basis.
Drought mapping in China: the accumulative evapotranspiration deficit for the 115 days period October '08 - January '09 (mm).
ET Tool can can assist in:
identification of local drought afflicted areas, which facilitates relief work in general;
identification of priority areas which require detailed study;
comparison between administrative districts for assigning aid relief; and
map environmental pressure on crops, wetlands and forests.