Investigating the role of physiographical factors on temperature-related parameters affecting evapotranspiration (Case study: Yazd province)

Evaporation is an important climatic phenomenon because of its effects on drought and climate change at regional scale. The principle weather parameters affecting evaporation are temperature، humidity، wind speed، sunshine and etc. Also physiographical factors like altitude and latitude would affect evaporation، as well. Main objective of the study is to evaluate the effect of physiographical factors on weather parameters affecting reference Evapotranspiration (ET). For this purpose، long-term climatic data of 10 meteorological stations at Yazd province were collected. Using multiple regression analysis، effects of altitude and latitude on climatic parameters at the selected stations were analyzed. Then، maps of these parameters were produced using corresponding altitude and latitude position of each pixel over the study area. Using Hargreaves- Samani equation and maps of weather parameters، map of monthly ET for the study area were generated using GIS-based capabilities of ILWIS software. Also spatial and temporal changes of ET were analyzed. Finally، effects of altitude and latitude، on climate related parameters of ET as two main physiographical factors were analyzed.