ارزيابي ژئومورفولوژيكي توسعه شهري و آسيب پذيري ناشي از زمين لغزش در دامنه هاي كوهستاني كلان شهر تهران

Geomorpholigic Assessment of Urban Development and Vulnerability Caused by Landslide in Mountainous Hillsides of Tehran Metropolis

The subjects related to Geomorphologic studies of Tehran metropolis from assessment aspect that developed during last half a century are numerous. One of the related issues is the analysis of vulnerability caused by landslide in mountainous areas during urban development. (Apart from strengthening the vulnerable area) avoiding these areas is an important solution to decrease damages caused by landslide. At this article, using Landslide Index Method (LIM) we have prepared the map of landslide zonation hazard in mountainous areas of the city, to determine risky strips. Considering the research has been done by the use of field visits and the experiences of the expert. The factors which are effective in landslide incidence in the region, include: lithlogy, elevation, slope of mountainsides, direction of mountainsides, annual precipitation, 24-hours maximum precipitation (high), distance from faults and distance from drainage system. Then we matched the final map of landslide zoning obtained from the above-mentioned method, to the map of urban region in mountainous areas. In this way constructed region have been distinguished from very high to very low zonation. These limits was compared to the present situation of Tehran Metropolis. The research procedure is based on analytical method. The key elements of this research are compiling of Geographic Information System (GIS). The finalized results indicate that some mountainous regions of Tehran Metropolis are apt to landslide with middle to high risk. At present 875 hectares (17.3 percent) of residential regions in mountainous parts of the city have developed in middle to highly risky strips. As a result, some residential units have damaged. The comparison of the present border of Tehran (especially in middle parts) to the borders of low and high risky zones (more than average) also indicates that these lines do not match well.