Landslide hazard zonation using LNRF model (Case study: Ghomroud- Aligudarz basin)

Determination and zoning of landslide hazard areas is a primary activity in environmental hazard management and reduce the landslide costs because this phenomenon is caused to financial and felon, soil and land degradation and increasing sedimentation in the watershed outlet. Therefore, identification of susceptible zones to landslide using experimental models is one of the basic steps in hazard management in basins. In this study, to effective factors in a landslide and also landslide hazard zonation in Ghomroud- Aligudarz basin was used LNRF model and GIS techniques. For this purpose, effective layers in landslide such as land use, lithology, rainfall, slope, aspect, distance to fault, distance from the river, Stream Transport Index and Topographic Wetness Index were prepared and digitized. The intersection of independent and dependent variables of mass movements and the weighting factor classes in each class have been executed based on LNRF model. The result of this investigation indicates that most of the landslide occurred in Gypsiferous and Sandy Marl, Shale with intercalations of limestone, Tuffaceous Shale and green Tuff units, slope class 5- 20 percent, and a north aspect. On the other hand, most of the instability occurred in rangeland and agricultural classes, a distance of 0-600 m from drainage network, and rain class 266-300 mm. Also, the class of 7.5- 10 for Topographic Wetness Index and class of more than 12 for stream transport index had shown the most susceptible to landslide. Also in the area, a landslide had a direct relationship to the distance of the fault and reflects the ineffectiveness of the faults in the landslide in the region. It is expected that based on these results, the best plan is done for the Ghomroud- Aligudarz basin, in particular, the construction of structures such as roads, building construction, and facilities to reduce the environmental and economic costs.