Estimation of Evapotranspiration of Rangeland Cover Using SEBAL Algorithm in Robat Mahidasht Region, Kermanshah, Iran

Rangelands are one of the most important plant ecosystems in Iran that have multiple and vital roles. In recent decades, with increasing population, increasing forage consumption, climate change and rainfall fluctuations, most of the country's pastures have been destroyed or faced with a regression trend. Therefore, in order to strengthen this vital ecosystem in the country, rangeland management components have a special priority and importance. One of the main components of rangeland management is the study of the water they need. The water required by the plant is equivalent to its evapotranspiration. Estimation of evapotranspiration using meteorological station data can be done at different time intervals; But determining its spatial distribution on a large scale is not possible. Remote sensing techniques and evapotranspiration estimation algorithms based on the surface energy balance of the earth are among the methods that are able to produce maps with appropriate spatial distribution that will be able to produce maps with appropriate time and place coverage. Then, using Sentinel 2 images and Maximum Likelihood classification method, the existing rangelands in the area were identified. The evapotranspiration plan of the rangelands was obtained. Based on the results, it can be seen that the error of estimating the actual evapotranspiration with the Sabal and Lysimeter algorithm is a maximum of 9.7%, which is very appropriate. The estimated evapotranspiration rates of rangeland cover at the four Landsat imaging dates were 2.1, 3.46, 3.4, and 3.44 mm / day. The results also showed less rangeland evapotranspiration than other coatings.