Prediction of the soil erosion in a forest and sediment yield from road network through GIS and SEDMODL

This study was conducted to classify water erosion risk for a deciduous forest and to predict the amount of sediment yield from forest road network.GIS in combination with AHP was used for determining the soil erosion risk degrees of forest.Beside,sediment yield from forest roads with gravel and asphalted surfacing was estimated using SEDMODL.Rainfall simulator was used in calibration and validation process of model.Results showed that47.9%of forest soil is classified from moderate to very high vulnerability.32.3%of roads were located in soil erosion risk class of very high.This class is generally found in the eastern region of forest,while areas with very low risk are found in the south western part.14.6%of the forest roads were ranked as having very low sediment yield.Only 61 segments out of 339 segments of forest road network delivered sediment to the ravine network.The estimated annual sediment yield for all of road sections by SEDMODL and rainfall simulator were 10,935.45 and10,509.29 g m~(-2),respectively.Results of the calibration and validation process showed that the variation accounted for in the predicted values by SEDMODL with the observed values under rainfall simulation was 3.90%.Best management practices(BMP) must be considered for the areas with high degrees of erosion risk.