Estimation of Potential Evapotranspiration with Estefnz Method and GIS Techniques in Eastern Azerbaijan

The accurate estimation of potential evapotranspiration is very important in water source management، agriculture، forestry and pasture sciences. Recently using of Geographical Information Systems (GIS) for accurate estimation has been developed and has showed good results. In this paper we estimate potential evapotranspiration in eastern Azerbaijan by Estefnz method. For calculation of coming net radiation (Rs) we used DEMSRTM images and solar analyst in ArcGIS software for 31 May، 10-11 am. After calculation of slope and aspects through digital elevation model، net radiation was estimated. The average temperature calibrates for elevation was imported in equation. Final maps show that the amount of potential evapotranspiration is between 0~15 mm/hour. Northern aspect and areas with high temperature have the higher potential evapotranspiration. Elevation and aspects are important factors than other factors in potential evapotranspiration control in the study area. The amount of evapotranspirtaion is higher than precipitation and therefore it is better that agricultural activities move to higher areas