Sensitivity analysis of estimated evapotranspiration using soil moisture content, energy balance model of SEBAL algorithm

Evapotranspiration is the main factor of plant growth, which can be estimated using different methods. Accurate estimation of evaporation and transpiration helps in planning to meet the actual needs of the plant. In general, daily evapotranspiration depends on temperature, climate, soil moisture, plant, growth period, root length, and the texture of the root zone porous media. In this study, the moisture balance of the soil surface is simulated daily and the components of deep percolation, evaporation, irrigation, and transpiration are calculated. The obtained results have been compared with the output of the surface energy balance algorithm for land (SEBAL) algorithm to determine the energy balance on the earth's surface and to estimate evapotranspiration. Normalized objective function (NOF), Nash–Sutcliffe efficiency index, and mean absolute error were incorporated into the problem for evaluating the predicted values. The energy balance of the soil surface and the moisture balance of the root zone each have a different process in estimating the actual evaporation and transpiration, but the correlation between them was acceptable. The interval between the calculated values can be used as input data to determine the irrigation requirement.