Evapotranspiration Estimation Basing on Surface Soil Moisture in an Arid Region of Northwest China

Crop evapotranspiration (ET) estimation facilitate the development of crop irrigation systems and regional irrigation water demand. The paper showed that, regardless of whether the occurrence of precipitation during the research period, a linear increasing relationship existed between spring wheat ET and surface soil moisture change. It allowed us to improve the ET precision with surface soil moisture measurement information. In field scale, surface soil moisture change was well collaborative used to estimate the spatial distribution of ET. The linear relationship between ET and surface soil moisture change can be applied to the regional scale. For two images of June 6, 2005 and June 22 as an example, the two estimates of surface soil moisture were used to estimate the regional ET. Compared with the SEBAL model results, relative error less than 25% of the spring wheat acreage is about 80%.