FORMATION MECHANISM OF DEBRIS FLOWS IN ROODBARAK SUB-BASIN , MAZANDARAN

In this study through field observations, 9 debris flows were investigated and their morphometric characteristics were determined in Roodbarak sub-basin. The most important morphometric characteristics of debris flows in this region are dip of debris flow’s head, dip of debris flow’s slope, length of crossing part, debris flow’s height and size of debris flow’s base. In order to analyze is these morphometric parameters acquired from debris flows of Roodbarak sub-basin, linear regression has been used for a meaningful analysis between parameters. According to the results of linear regression, maximum coefficient of determination of the size of debris flow’s base is computed with the independent variable of debris flow’s height (0.89) and after that with the length of crossing part (0.55) that shows more justification and determination of variation in the size of debris flow’s base with these two parameters. After these two parameters, the coefficient of determination for slope’s dip is 0.37 and the weakest coefficient of determination for dip is the one between head and slope of the debris flow having the current base. The results of quantitative analyses between the volume of debris and other independent variables also show that with a coefficient of determination of 0.95, the variable related to the length of crossing part has the most correlation with dependent variable (the volume of debris). Afterwards, the coefficient of determination for the crossing part was determined 0.82. Using the factor analysis, the most important factors in variation of the size of debris flow’s base and debris volume were determined as the respond variables. Regarding to the results of factor analysis by rotation of varimax, 3 effective components on variation of the base size of debris flows in Roodbarak sub-basin were determined that the first component has a dip of 0.95 for debris flow’s base, justifying 45.5 percent of changes of variance and is the most effective component on the respond variable. In this component, the height of debris flow and the length of crossing part with coefficient of 0.97 and 0.88, respectively, have a strong positive relation with the respond variable (the size of debris flow’s base) and are the most important parameters of variability of this dependent variable. In the first component, slope’s dip has a strong negative relation with dependent variable (the size of base); in other words, the size of debris flow’ base gets smaller when slope’s dip gets increased. For the dependent variable of the volume of debris, two effective variables on this variable were acquired by application of factor analysis; these two components justify 75.2 percent of changes of variance. First component with a coefficient of 0.96 is the principle effective component on variation of debris volume that justifies 54.7 percent of variance changes. [Sadroddin Motevalli, Mohammad Mahdi Hosseinzadeh, Reza Esmaili, Khabat Derafshi and Hasan Shaebaninia. FORMATION MECHANISM OF DEBRIS FLOWS IN ROODBARAK SUB-BASIN, MAZANDARAN, IRAN. Life Sci J 2013;10(1s):8-20] (ISSN:1097-8135). http://www.lifesciencesite. com. 2