Soft isostasy in geomorphology

Earth subsidence has been one of the important issues jeopardizing environment and there are many studies, which blame shortage of underground water resources for having uplift and subsidence. However, many argue such conclusion and believe that earth subsidence has been studied in the past without considering the changes in the hill over a long period. In this study, we use SAR interferometry study to investigate earth subsidence in dessert areas of Esfahan, Yazd and Ardakan, located in central part of Iran. The results indicate that there are more important issues affecting subsidence such as the uplift in the hills located the desert area. The results of the survey based on SAR interferometry reveals that subsidence occurs with the uplift in the adjacent hills, simultaneously called Soft isostasy in geomorphology. In other words, the subsidence is more associated with the movement of the surface of the desert to reach equilibrium than shortage of underground water resources. There is an equilibrium line between the uplift and subsidence where is changes of the surface tends to zero.