Energy Model to Predict Suspended Load Deposition Induced by Woody Debris: Case Study

Large woody debris (LWD) has been used repeatedly to create aquatic habitats. This study attempts to quantify and predict geomorphological changes induced by LWD. Six cylindrical bundles of LWD were anchored in a stream in central Ohio, and bed elevations were monitored for up to seven months. A model was developed to predict deposition downstream of the LWD. Sediments accumulated immediately downstream of the LWD structures. The average accumulation depth 0.25 m downstream of the LWD was 0.10 m. At 1.25 m downstream, accumulation depth averaged 0.07 m. The model to predict the sediment deposition had R^2 values of 0.87-0.77, respectively, at the two downstream locations. The most important terms in the model were the Froude number and bankfull depth. An advantage of this model was the use of easily measurable variables including average bankfull velocities, depth, and cross-sectional area. This fact will facilitate the use of the model in field settings. Suggestions for future improvements to the model include calibration/validation in different streams, inclusion of a temporal variable, and sediment characterization.