Study on effective factors causing landslide in the southwest of Khalkhal by using crosstables and chi-square method

Landslides, which happen usually in rural regions of southwest Khalkhal, not only cause considerable economic loss, but also provide social and cultural damages. This may effect the development project that are going to be implement in this area. This study was conducted to understand and analyze the contributing factors to these landslides and slope movements, so that the findings could be used in planning different projects such as new construction developments, improvement of agriculture, protecting the soil resources, environmental issues, and economic activities. After identifying all the landslides of the region, based on the existing aerial photos and the compiled field data, basic geological maps, slope gradients, land use, distribution of the landslides, annual rainfall, and length of the rivers and roads, the area of the buildings and the number of the waste water wells were prepared at 1:50000 scale. Then , statistical analysis based on cross table and chi – square method were applied. The coefficient values and the correlation of each factor with the landslides and slope movements were calculated and compared with one another. The results showed that there are significant differences between different types of factors and their contribution to slope movements, and the degree of difference varied from factor to factor. The results also showed that rock composition is the main factor which contributed to landslide occurrence. Other factors such as land use, distance from major faults, slope condition and rivers’ undercutting played a role obtained in landslide occurrence. Based on the results, practical and scientific methods were recommended for lowering the amount of direct and indirect damages.