بررسي عوامل موثر در فرونشست زمين دشت اشتهارد

Effective Causes of the Ground Subsidence of Eshtehard Plain

Gradual and accidental sinking of subsidence of the grouud is a phenomenon which occurs because of natural and artificial evolutions. Such a sinking could have disastrous damages. On the opposition, the gradual sinking has slow process and mostly occurs because of extraction from underground liquids (water and oil). Eshtehard region because of neighboring with Tehran and Karaj, and specific situation, has some particular morphological views. In this research through the use of 7-LAN sat pictures,1:25000· topographical maps,1:100000 : geological map, ILWIS and arcGIS software, documentary and experimental studies, statistic of water level in Eshtehardʹs wells between 1379 to 1383 , and pedology, rock formation and type of geological formation of region has been studied and demanded maps has been prepared. The results show that the important reasons of ground sinking in the region are the existence of oven-ducts, and underground water level decreasing caused by unstructured usage, and the existence of evaporating formations. Nowadays the sinking problem has a great importance for engineers and planners (Goudarzinejad, Shapour, 1378, p. 310), and the results of studies indicate that the process of Eshtehard development has created environmental problems. Regarding tectonic dynamicity of region, damaged residential buildings are in danger