Estimate Precipitation Changes in the East and West of the Zagros Main Thrust

AbstractIn relation to the effect of unevenness and precipitation, two issues have occupied the mind of researchers: First, the effect of altitude on increasing rainfall, and second, the effect of unevenness on the creation of deserts. The combination of these two effects has made it impossible to estimate a regression relationship between Zagros altitude and precipitation with a significant coefficient of explanation. The purpose of the present study is to investigate the precipitation situation in the western (rain-facing) and eastern (rain-sheltered) slopes of the Zagros main thrust and to create wind-sheltered (rain-sheltered) areas. To investigate the effect of the Zagros Mountain Range in the creation of sheltered areas, the function and relationship of the factors of altitude and precipitation were investigated as effective parameters in the creation of different slopes of this mountain range. Maps of both precipitation and altitude were extracted for the Zagros Mountain Range. According to the results obtained from examining the relationship between the maps of precipitation and altitude, it can be said that the increase in precipitation in the windward slopes has significant coordination with the increase in altitude, but the increase in precipitation does not continue until the main thrust of Zagros. In most of the regions, the maximum rainfall occurred before the maximum height of Zagros (corresponding to the main Zagros Thrust). When passing through the Zagros thrust despite the significant height of the region, the amount of precipitation has significantly decreased. In the northern parts of Zagros, the biggest change of precipitation has happened in the wind shelter part, in the vicinity of the highest peak. Considering the high altitude in the sub-basins to the east of the Zagros Thrust, as well as their lower slope compared to the basins located in the west, they receive less rainfall due to their sheltered position. But since they have more receiving surface and because of the high altitude, they receive most of the precipitation in solid form. More penetration of water into the ground is possible during the stages of snow melting. In addition, this phenomenon has considerable ecological effects.Keywords: Zagros Main Thrust, Wind Sheltered Desert, Dry Areas, Rain Shadow. IntroductionIran is a vast mountainous land that covers most of the plateau with the same name (Mahmoudi, 1988). The southwestern mountainous unit of Iran is known as Zagr