Mississippi River Bedform Roughness and Streamflow Conditions near Vicksburg, Mississippi
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS VICKSBURG United States
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Bedforms are a consequence of flow of sufficient magnitude over a mobile sediment bed. They are a primary component of the drag acting upon a moving stream, yet are infrequently explicitly treated in numerical models of fluvial sediment transport. This study aims to document the collection of bathymetric data in the Mississippi River in an area of persistent and dynamic bedforms over a range of flow conditions, statistically examine bedform geometry, and parameterize results for inclusion in numerical models. Bathymetric data were collected several times to measure rates of bedform transport. Linear profiles of the bedforms were extracted from the bathymetry and analyzed for roughness and dune population statistics. These statistics are compared with the flow conditions under which the bedforms were observed. Bedforms increase in size with discharge and decrease in steepness height length ratio. At extremely high discharges, bedforms begin to decrease in size. In comparing results with methods for calculating form drag coefficients, it was observed that the dunes at higher river stages, despite their greater size, may present less resistance to flow due to their reduced steepness and reduced relative heights dune height flow depth.
- Hydrology, Limnology and Potamology