Investigation of effective factors on landslide occurrence and landslide hazard zonation...

Investigation of effective factors on landslide occurrence and landslide hazard zonation – Case Study Shirin Rood Drainage basin, Sari, Iran

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kelarestaghi, A
M. S (high expert ) , Faculty of Natural Resources , University of Tehran
Email : [email protected]

S. Feiznia
Full Professor , Faculty of Natural Resources , University of Tehran

Abstract
In drainages basins of northern part of Iran , combination of natural and human factors have caused numerous landslides and a lot of damages due to landslides . For restricting the activity of landslides one of the main solution is to avoid these regions. For doing this, landslide hazard zonation map of the area should be prepared and low hazard and high hazard zones should be separated . In this research nine following factors were recognized as effective factors in landslide occurrence : slope , Altitude , aspect , rainfall , landuse , geology , distance from faults, distance from roads and distance from main drainges . After overalying the map of landslide occurrences with the maps of the above-mentioned factors, it was recognized that aspect and distance from main drainages have little effect on landslide occurrence . Then by considering the other seven factors, landslide hazard zonation of the area was done using two following methods: index overlay, valuing area accumulation.

The results of this research have shown that in two methods, the regions in which land use changes have occurred seriously , belong to high-hazard zones and inversely , regions in which forests have not been destroyed , belong to low-hazard zones. After this phase the evaluation of zonation methods was done . For doing this , two following methods were used: checking by the use of landslide occurrence map , using accumulation ratio in each of hazard classes. The results of two methods have shown that in index overlay method, different hazard zones were separated better.