Investigation on some environmental factors influencing water erosion (Case study: Ghara aghaj basin)

The purpose of current study is to investigate the effects of some of environmental factors on erosion value، to find the most important governing factors and the relation between erosion of working units and environmental factors (soil characteristics، slope، aspect، elevation، lithology، geomorphology faces and vegetation cover percentage). Working units map was prepared using geomorphology method. This map was derived by overlaying slop، aspect، elevation، lithology and geomorphology faces maps. In order to study plant cover random-systematic sampling in each working unit was conducted in 10 plots. Regarding the species type and distribution the area of each plot was determined based on the minimal area method. Canopy cover of species was determined in each plot. Furthermore، 5 profiles were sampled within the working units to study soil characteristics in 0-50 cm depth. Subsequently، the texture، percent of lime، organic matter، gravel، pH and EC were measured. Erosion value was determined in each working unit using E. P. M. method. Statistical analysis was done using the Principal Components Analysis (PCA) through PC-ORD4 software program. The results showed that among environmental factors، vegetation cover، slope، stone resistance، organic matter and aspect as the first set of factors determine the change in erosion value by 54. 35% while the second set of factors، including loam and clay percentage play contributes to the change by 26. 96%. These two sets of factors altogether explain 81. 31% of erosion value variation in Ghara aghaj basin.