As a result of the research analysis of calculation methods for determining evapotranspiration carried out in different regions of the world it was established that the development of the models for evapotranspiration had been widely spread in the most of the developed countries. In Russia, which has a considerable diversity of soil-climatic conditions, for the most regions the own methods for evapotranspiration were developed by different research organizations. In the North of Russia such methods were developed by S. I. Kharchenko and A. R. Konstantinov, in the South – by G. K. Lgov, S. P. Nevskiy and D. A. Shtoyko, especially for irrigation regions, in Siberia – by V. S. Mezentsev, in central part of Russia is widely used the methods of N. N. Ivanov with the adjustment of Molchanov and bioclimatic method of A. M. Alpatyev. In recent decades of the ÕÕ century the bioclimatic method has been spread through the whole country, but the laboriousness while bioclimatic coefficients determining has limited its application. The Penman Monteith method is widely spread abroad. FAO recommended using this method as the reference one. Actually, all calculation methods base on climatic indices. The main indices are radiation balance during the growing season of phytocenosis, sum of mean daily air humidity deficit and air temperature for the same period, and wind speed. Such methods have simple models and can be easily and timely used for either operative calculation or predictive ones. Calculating errors will be within acceptable limits by using the methods in conditions identical to those for which they were designed. But due to regionality, the chosen method should be adjusted for the particular territory by using correcting coefficients taking into account topographic features, irrigation technology, the crop and so on.
Keywords: evapotranspiration, crop water consumption, calculating methods, model for evapotranspiration.
