Evaluation of land subsidence using GIS technique (Case study: Tehran and Alborz provinces)

The management and habitation planning have been increasingly considered to reduce the consequences of natural disasters due to the societies’ growth and development. Tehran and Alborz provinces have hazard potential and critical conditions because of their specific natural and regional situation, high population density, congested texture and vital routs. Studies show that morphological phenomenon of subsidence in these two provinces is happening rapidly. This study was done in a descriptive-analytic method. The data were collected through the study of documents, books and articles and three main maps of land subsidence hazard, vulnerability and risk will analyze following the inference of main factors and using AHP to subsidence indicators in GIS software. The results of this survey indicate that lack of proper control and management of underground water resources will cause the risk of the land subsidence as a hazard in these provinces; as well as the lack of continuous monitoring of underground water resources in these regions and the undesirable urban development in the bounds of subsidence may cause irreparable damages to human, economics, infrastructures and the environmental resources in these provinces. This paper concludes that policymaking and planning in these provinces should be based on hazard maps and appropriate to the hazards and damages due to land subsidence in areas susceptible to land subsidence. Vast areas in Tehran province such as the west and southwest regions, as well as Varamin plain, Shahriar, Karadj, Nazarabaad and Savojbolagh in the Alborz province are among the susceptible to land subsidence; this indicates that founding and development of biological and demographic centers and, in general, any civil activities in these areas demanding special sensitivity and require the evaluation, monitoring, control and continuous protecting the influential factors in the likelihood occurrence and intensification of the land subsidence phenomenon in the region.