Modeling Soil Erosion and Transport on Forest Landscape

Century-long studies on the impacts of forest management in North America suggest sediment can cause major reduction on stream water quality. Soil erosion patterns in forest watersheds are patchy and heterogeneous. Therefore, patterns of soil erosion are difficult to model and predict. The objective of this study is to develop a user-friendly management tool for land managers to design forest management activities (e.g., road building, prescribed burning) that may minimize water quality impacts. This system has the capability to predict long-term soil erosion and sediment transport from hillslopes to stream networks under different climate conditions and forest management scenarios. A Geographic Information System (GIS) coupled with the Universal Soil Loss Equation (USLE) model was used to facil itate database development, manipulation, and output display. The 1140 ha watershed was divided into 30 x 30 m grid cells and gross soil erosion was first predicted by the USLE model for each cell. The Arc/Info GIS utilities are employed to calculate the total mass of sediment moving from each cell to the nearest stream network. Field measurements were used to develop sediment movement routing functions. This study concluded that poorly managed roads are the main source of sediment in a forested watershed. The spatial location of forest roads affected sediment contribution to streams.