To meet legal mandates requiring the prevention and control of excessive soil erosion and sediment generation, Department of Defense (DoD) installations need an accurate, easily obtained, and cost-effective method to predict sources and sinks of eroded sediments generated on their properties. Currently available erosion and sediment models are hampered by the fact that they were developed for fairly uniform agricultural landscapes and do not accommodate topographic or land-use complexity. The objective of this project is to demonstrate and validate the Unit Stream Power Erosion and Deposition (USPED) model developed under the Strategic Environmental Research and Development Program (SERDP).

The USPED model is built on the backbone of the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) models produced by the U.S. Department of Agriculture. Although the USLE and RUSLE models are widely accepted and used for agricultural purposes, they are deficient when it comes to the complex topographies typical of DoD managed lands. The primary improvement offered by the USPED model is the manner in which it accommodates complex topography. Whereas the former models consider landscapes to be a series of large planes, the USPED model considers divergence and convergence of slope by modeling, in a geographic information system environment, the entire upslope area that contributes to the overland flow of water across every point in the landscape. The model more fully accounts for topographic complexity by considering both profile curvature (in the downhill direction) and the tangential curvature (perpendicular to the downhill direction). It computes both soil erosion and sediment deposition as the change in sediment transport capacity in the direction of flow. The USLE and RUSLE do not predict sediment deposition within the landscape.  

In this project, USPED estimates will be compared with visual estimates of soil erosion and deposition in the field. Whereas the USLE and RUSLE frequently and significantly overestimate actual soil erosion (because they do not estimate in-field sediment deposition), the demonstration will be considered successful if the model estimates agree with visual estimates more than 80% of the time.

It is anticipated that the USPED model will provide significant capability to DoD land managers to accurately predict soil erosion and sediment deposition both spatially and volumetrically, thereby enabling them to allocate limited land rehabilitation dollars to portions of the landscape with the greatest need of remediation. The model also can be used to identify areas least capable of supporting increased disturbance without becoming noncompliant with non-point source pollution standards. (Anticipated Project Completion - 2016)