Determining the effective Parameters and their Optimal Combination in Order to Model the Rill Erosion

Abstract

Rill erosion is under the influence of several factors that determine the most effective parameters. To select the optimal combination some of the following factors, for modeling this type of erosion seem to be essential. One of the factors of soil degradation in the hills of Mashhad vicinity is a kind of rill erosions that makes the recognition of the behavior and control essential. So in this research by establishing 50-m transects in each different slope length, effective parameters in shaping rills, including canopy cover, ground cover, gravel, sand, silt, clay, slope and its common effect on length have been measured. By measuring, widths and depth of any rill and their geometric section, surface area of rills have been calculated. Gamma test has been applied to find optimal combination of input parameters. Whereas the statistical tests including gamma, VRati, gradient, and standard error were different, combined statistics index of MIPE has been employed. This statistic criterion shows parameters composition including surface gravel, silt, slope and its common effects on length to be the optimal model. Ground cover, amount of silt and grave surface respectively play more important role when the priority of their effect is to be considered.