Author(s): F. Jan Nesar; A. Khashei Suiki; S. R. Hashemi; S. Moradi Kashkooli
Keywords: No keywords
Abstract: So far, various methods were presented for determining the reference crop evapotranspiration in different parts of the world. The most popular and prestigious of them can be combined methods of Penman family, modified Blany-Criddle, Hargreaves–Samani and thornthwaite. Due to the lack of the lysimeter data in many parts of Iran, presenting an equation according to the regional condition with high precision is so paramount. The aim of this paper is presenting a method with higher precision for determining the evapotranspiration of the sugar beet in Torbat_Jam by using the meteorology and GDD (Growing Degree Day) parameter and determined methods were evaluated with FAO-Penman-Monteith method as a standard model for determining the evapotranspiration. RMSE, R2indexes, and Nash-Sutcliffe index, NS, were used for comparing fitness indexes. Results showed that number four equation is appropriate for calculating the water requirement of crop. So R 2, RMSE indexes and Nash-Sutcliffe coefficient were 0.683,1. 117 and 0.99, respectively for equation 9.