Evaluation rainfall factor in the occurrence of landslide margin of the forest Road (Case Study: Watershed of Pahne kolla)

Landslide phenomenon results in moving material on the hillside by the force of water and gravity.This Paper has attempted to study the factors of rainfall in the occurrence of landslide phenomena in the Forest of Mazandaran watershed. This watershed is located in the Pahne Kolla area and is the harvesting location of Tajan Wood and Paper Industries. Measured rainfall from the years 2002 to 2011, were analyzed in this study. These data show that the greatest amount of rainfall and number of landslides occurred in 2005 in the forested areas of Tajan. According to field visits the total area of the landslide surface for 2011 is 141/2 acres. The destruction caused by landslides has increased the cost of road maintenance over the 10years ego. The ratio, of landslide surface area to total surface area was calculated, Analysis of data was performed by entering the independent variable (rainfall) and the dependent variable (number of dots scrolling) into Excel software. The correlation between rainfall and number of landslides was studied using the Pearson method to-test for a regression series. Analysis of these results suggest that in 2002 there was an increase in landslide activity that was associated with an increase in and that there is a positive and significant correlation between rainfall amount and landslide activity results Show that rainfall is an important factor in creating landslides within the study area.