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United States Department of Agriculture

Agricultural Research Service

Title: Temporal Variations in Point Bar Morphology Within Two Incised River Meanders, Goodwin Creek, Mississippi

Authors
item Bennett, Sean
item Simon, Andrew
item Kuhnle, Roger

Submitted to: International Conference on Water Resources Engineering Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 15, 1998
Publication Date: N/A

Interpretive Summary: The erosion, transport, and deposition of sediment in agricultural watersheds plays an important role in the loss of usable land for agriculture and agriculturally-derived sediments and chemicals can severely impact water quality and ecology. Along stream meanders, sediment such as sand and gravel can be stored as bar deposits. These bars may act as temporary or permanent storage sites depending on whether the bend is actively moving or migrating, and the magnitude of the flows passing through the reach. Two meander bends along Goodwin Creek, MS, were chosen to examine the time-variation of point bar morphology over a two-year period. Sediment erosion generally occurred during Winter/Spring months, was associated with moderately high flow discharges, and bar surface texture tended to become coarser-grained. Sediment deposition generally occurred during Summer/Fall months, was associated with the highest flow discharges, and bar surface texture tended to become finer-grained. The net changes at each site occurred in synchronicity and of nearly equal magnitude. The bars are growing vertically at a rate close to 30 mm/yr, and they are migrating laterally at a rate close to 3 m/yr.

Technical Abstract: Two meander bends along Goodwin Creek, Mississippi, were chosen to examine incised-meander migration processes, bank failure mechanics, and point bar response. Detailed topographic surveys of the point bars over a two-year period reveal discrete episodes of net change in bar morphology. Sediment erosion generally occurred during Winter/Spring months, was associated with moderately high flow discharges, and bar surface texture tended to become coarser-grained. Sediment deposition generally occurred during Summer/Fall months, was associated with the highest flow discharges, and bar surface texture tended to become finer-grained. The net changes at each bendway site occurred both in synchronicity and of nearly equal magnitude, and show net vertical accretion rates of 30 mm/yr.

Last Modified: 10/23/2014
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