Submitted to: Soil Conservation and Water Quality Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 1995
Publication Date: N/A
Technical Abstract: The WEPP hillslope and channel erosion components use steady-state sediment continuity equations to estimate sediment movement down hillslopes and down channels. Hillslopes are conceptually divided into rill (small concentrated flow paths) and interrill (regions between rills) areas. In the hillslope continuity equation, the change in sediment load with distance down the slope in a rill is equal to the sum of the sediment delivery rate laterally from the interrill regions plus the detachment or deposition rate in the rill. Rill detachment is predicted when the sediment load in the flow is less than the flow sediment transport capacity and flow shear stress exceeds the critical shear stress value. Deposition in rills is a function of sediment load, sediment transport capacity, flow discharge rate, and sediment particle characteristics. Deposition in rills is predicted when the sediment load in the flow exceeds the flow sediment transport capacity. The channel sediment continuity equation is almost identical to the hillslope equation. The change in sediment load with distance down a channel is equal to the sum of the sediment delivery rate (from contributing hillslopes and impoundments, if any exist for the current channel) plus the detachment or deposition rate in the channel. The sediment delivery is computed in the hillslope and impoundment components of the WEPP model and provided to the channel routing routines. Channel detachment occurs if channel sediment load is less than channel sediment transport capacity and shear stress acting on the channel exceeds the critical shear stress value. Deposition of sediment in the channel occurs when channel sediment load exceeds the channel sediment transport capacity.