An experimentally derived model for actual evapotranspiration

Abstract Experimental data from several different climatic regions were used to develop a statistical model for actual water loss rates from land surfaces. The actual evapotranspiration rate was considered to be influenced by the amount of available water in the soil and by meteorological and plant conditions which determine the potential evapotranspiration rate. Experimental measurements of these three variables from various environmental conditions were combined into a single model expressing the composite relationship. Actual evapotranspiration rates were calculated from this relationship using the variables soil moisture and potential evapotranspiration. Initial testing showed that the model gave satisfactory results when used for estimating moisture changes in the soil.