Abstract
Evapotranspiration must be evaluated for analyzing in detail the moisture movement below ground surface which covered with plants. A new equipment for measuring the evaporation or evapotranspiration has been developed. The accuracy of the evaporation measurements has been successfully examined. This technique can be applied to measure the evaporation with high accuracy. Evapotranspiration from three kind of plants as well as the evaporation from water and soil samples were experimentally studied with changing the humidity condition, the temperature condition and the wind condition. It was clearly found that the evapotranspiration from these plants was not so much influenced by those conditions as compared with the evaporation from water and soil. This nature may imply that the evapotranspiration has been controlled by these plants. Field measurement has been performed in two different places at the same time, the first place had vegetation and the second place had no vegetation. Evapotranspiration from the vegetation field was larger than evapotranspiration from the no vegetation field. The transient change of the measured evaporation rate was almost parallel to the change of net radiation.
