Statistical Analysis of Some Morphometeric Characteristics and Effective Factors on Landslide Occurrence in Sajarood Watershed

The purpose of this study was to analyze some physical, morphological and effective factors on landslide occurrence to better recognition of landslide mass behavior in the study area. Based on the mean annual rainfall of 25 years period and elevation above sea level of 12 stations located within and surrounding the study area, the rainfall gradient equation of the area was developed. Based on field surveys, aerial photographs interpretation and filling out questionnaires of landslide, some important morphometric factors including landslide deformation coefficient, landslide longitudinal deformation coefficient, landslide latitudinal deformation coefficient and landslide depth index and some effective factors on landslide occurrence such as distance to fault, manner of relation to drainage network, elevation and mean annual rainfall in 35 land sliding locations were computed. The results of statistical analysis including correlation analysis and linear multiple modeling between effective factors and landslide morphometric characteristics showed that most landslides were long with deep extension and very low longitudinal deformation and latitudinal deformation in comparison to depth. Also, decrease in elevation above sea level and increase in mean annual rainfall, have resulted in deeper and with latitudinal extension landslides, while longitudinal extension of landslides decreased. In the study area considerable amount of sediment was delivered to drainage network. because of the proximity to drainage network and land use change from forest to garden and roads in lower elevations.