Comparative Study of Climate changes and Geomorphologic Evolutions in Maharloo

There are some Geomorphologic evidences of climate changes as alternate dry and wet climate in central parts of Iran. Maharloo Lake is a location that has protected the mentioned evidences as surfaces of detrital and evaporating sediments. The Lake drains an area of 4266 km2 and its present- day climate is dry so that evaporation is more than precipitation. Its climatic and lithological conditions have resulted in the evolution of lake as a playa. In other words، flood plains and low traces around the lake indicate the wet climate. The purpose of this research is to detect the changes of the lake area. Topographic map at a scale of 1:25000، Aster Digital Elevation Model، ETM+ and IRSP6 satellite images، Geological map at a scale of 1:100000 and field research were used in this study. Principal Component Analysis and Optimum Index Factor (OIF) techniques were done to detect the area around the lake، and the results were assessed with field works and sampling. The Results of this study showed that the lake has been received more rainfall during the cold last glacial period and that its area was about 517. 6 km2. Due to the presence of evaporation mineral such as Calcite، gypsum and Halite in the rocks of the basin، and due to the decrease of rainfall and increase of evaporation because of climate change، the lake became smaller and evaporating minerals were deposited based on their own solubility، and then calcite، gypsum and salt zones were formed around the lake and consequently Maharloo lake was evolved as a Playa. The presence of Halite in others zones represents that climate change after the first dry period has resulted in the change only in salt zone، but not in the stopping of playa development.