Assessment of Forest Roads Sediment Yield using WARSEM, SEDMODL and Direct Measurement through Rainfall Simulation

In this study, the sediment yield of forest roads of Darabkola watershed was investigated and estimated using WARSEM and SEDMODEL. Rainfall simulator was applied to measure the sediment of abovementioned roads directly. In order to apply WARSEM and SEDMODEL models, field operations for measurement of different parameters including road length and width, height and coverage of road cut-slope, road longitudinal slope, shape and configuration of the road, road surface, and etc. were carried out in 63 different segments of the path of forest roads in the study area as 11979 meters long. Then sediment yield of roads was measured by rainfall simulator with nozzle of 3 meters high and plot of 2 square meters. Results of the WARSEM and SEDMODL models and rainfall simulation showed that sediment yield of forest roads are equal to 9.918, 5.109, and 4.141 kg/m2/year, respectively. Results also showed that there was no significant difference between sediment yield of rainfall simulation and SEDMODEL at significance level of %95. It was also revealed that SEDMODL is more suitable for estimating sediment yield of forest road with values of RD, MD, BIAS, RE and RMSE equal to 21.42, 4.54, 0.04, 17.59 and 0.71, respectively.