The Effect of land Use Change on Runoff Fractions and Soil Loss Using Rainfall Simulator Chaharzbar e Olia in Kermanshah Province

The aim of this study was to evaluate the impact of forest on erosion and runoff variables and compare it with rangeland and agricultural in part of Mereg watershed located in Kermanshah province. At first, three forest mass were identified and divided into three density categories (low, medium and Many), then Soil and hydrological parameters were measured in each forest density area and also in both agricultural and rangeland using a rainfall simulator. Rainfall was run at a rate of 83 mm / h for 24 minutes with 18 repetitions. The hydrological results in forest mass showed that the mass 2 (with medium density) produced 32.6 percent more runoff than the first stand and 33.5 percent more than the third Mass, which could be due to the soil repellency in forest, but no statistically significant difference was observed in other variables. Also, the comparison of the hydrological variables in three land uses (forest, rangeland and agriculture) showed that although the runoff from forest was 61.5 percent more than rangeland and 54.2 percent more than agricultural, however, the amount of sediment output from these plots was 62 percent less than rangeland and 91percent less than agricultural. This decrease in rangeland compared to agriculture was 76.26 percent.