Master of Environmental Science, Miami University, 2006, Environmental Sciences

This study investigated the impact of high-stage events on riverbed scour and hydraulic conductivity (Kv). Seepage-meter measured riverbed Kv averaged 0.092 m/d. Slug-test measured Kv of the underlying sediment averaged 9.6 m/d. The low riverbed Kv is probably due to a gravel and cobble layer clogged with fine sediment (colmation layer). Kv of cores of transient material overlying the cobble layer averaged 5.3 m/d. Event-driven scour, measured with cross-sectional profiles, scour chains, and a load-cell pressure sensor, never exceeded 0.06 m, indicating that the colmation layer remained intact, despite even a 60-year event. A riverbed conceptual model of three distinct layers –transient sediment, an armor/colmation layer and a transitional bottom – had an overall Kv of 4.6 m/d. Sensitivity analysis of layer thicknesses indicated that a) the transient layer has negligible impact on the overall Kv and b) loss of the colmation layer, while not observed, could double the overall Kv.

Committee: Jonathan Levy (Advisor) Subjects: