Abstract

The present research has been conducted aiming at simulation of the effect of climate changes on evaporation in Yazd. This research considers both the changes of the trend of the observational meteorological data in the past decades and the changes of the future decades. In evaluation of the evaporation data of the Yazd in the past decades, the statistical period of 1953 to 2009 has been considered.  In the next step and in order to identify the changes of temperature of the future decades, meteorological data has been simulated based on Global Climate Models (also known as General Circulation Models, GCM). To do so, GCM model have been used based on a single scenario called P 50.Consequently, the results show that temperature rise occurs in all studied months, while these variations in annual temperature rise is accompanied with temperature rise of +0.35°C in every decade from 1953 to 2009. But after simulation of temperature changes for the future, the results indicated that the Yazd’s temperature in 2100 would have an increase of 4.25°C in comparison with the average temperature of the period from 1960 to 1990. Also, in general, by simulating evapotranspiration rate, it has been found that in most months of the year, especially the warm seasons (spring and summer), evapotranspiration rate is more than the long-term mean, so that we would experience warmer springs and summers than previous decades. On the other hand, considering the fact that evapotranspiration rate would have the increase of 684.31 mm to the long-term mean by 2100, the intensification of water requirement in different areas especially agriculture may appear as a big problem and great crisis. In such a climatic condition, there would be no place for dry farming, so the main focus is mostly on irrigation, which is itself faced with serious problems because of unavailability of water resources such as lakes, rivers, etc. 

Key words: Simulation, global climate models, arid region, evaporation, water requirement, Yazd.