Critical analysis of the contemporary methods for estimating reference evapotranspiration

Evapotranspiration is one of the most important processes within the hydrological cycle whose reliable assessment is essential in the planning and managing of land and water resources. Besides that, the water needs of plants depend directly on the size of evapotranspiration. This paper presents a comparison of reference evapotranspiration values calculated using the FAO Blaney-Criddle method, the FAO Radiation methods, the FAO Penman and the FAO 56 Penman-Monteith method with the results of measurements of evapotranspiration at the meteorological station in Kosutnjak during the growing seasons of 2004, 2005 and 2006. It is shown that the application of the FAO 56 Penman-Monteith equation provides the calculated values of evapotranspiration that are closest to the results of measurement and it is recommended to apply this method for the estimation of reference evapotranspiration.