Evaluation of land subsidence related disasters in plains and residential areas of Iran

Land subsidence caused by heavy exploitation of groundwater is an acquaintance morphological phenomena occurrence Iran. Recently the areas involved with this phenomena has been rapidly increased, covered most part of Iran’s areas from desert land in center to semi moisture areas in west and north-west. This is mainly due to saver frequency drought occurred during last decade. The wide distribution of land subsidence occurrence over residential areas has brought serious problems and damage which appeared this phenomenon in form of Geo-Hazard for the country. As the most part of the areas involved with land subsidence are located in a high seismic zone, the simultaneity of land subsidence with earthquake occurrence can inclemently increase individual damage from each and converting these events to the disaster. The present research deals with lands subsidence areas identification and mapping for disaster evaluation over the counter. In other to extract the land subsidence vulnerability and hazard over the Iran’s areas, the land subsidence outcome map was superimposing with settlement and infrastructure distribution map. In the next step, the vulnerable residential and infrastructure areas where overlaid with seismic hazard map to estimate and predict probable disaster. Thus, to mapping land subsidence over the country, the 18 areas where reported as land subsidence prone areas has been extracted from previous studies, where in 15 more areas the phenomena was measured using Differential Interferometric Synthetic Aperture Radar- D-InSAR techniques. The result of superimposing land subsidence map with seismic zonation map of Iran showed most land subsidence areas are located in a high hazard seismic zone. The reach outcome also shown earthquake occurrence over the land subsidence prone area can be a trigger for land collapsing over residential area, which can make double disaster. Moreover, land subsidence hazard can cause flood hazard over the residential areas where are not involved with this hazard so far. This is because of changing the river bed morphology and land downfall due to subsidence phenomena.