Estimation of reference evapotranspiration using FAO-Penman-Monteith method and its zonation in Yazd province

Iran is a part of the world's arid and semi-arid areas and encounters severe lack of water resources. Evapotranspiration is a major component of the hydrological cycle and its precise determination has a high importance in the studies of hydrological balance measurement, design and management of irrigation systems, product yield simulation and design and water resources management. At present, there are various methods for calculating the reference evapotranspiration. According to some researches, FAO-Penman-Monteith method is the most accurate method for the estimating of both dry and wet weather conditions after lysimeter weight method. In this study, the amount of reference evapotranspiration was calculated using FAO-Penman-Monteith method in 29 selected synoptic and climatology stations in Yazd. Then, they were classified in two ways: Firstly, through an establishment of a relationship between evapotranspiration parameters and height, and secondly, through Inverse Distance Weighting (IDW). Finally, variations of reference evapotranspiration in different land cover throughout the province were analyzed. Method Reference evapotranspiration maps show that the amount of evapotranspiration is higher in central, southern and some western areas of the province than in northern and eastern areas.