Bedform Analysis For Select Flows In The Mississippi River At Vicksburg, Mississippi

Quantification of sediment transport rates is necessary for river management, but the measurements are difficult to acquire due to large volumes of sediment in motion, spatiotemporal heterogeneity in river conditions, the need for expensive equipment, and high personnel costs. Repeated measurements of bed topography, collected at different times for the same reach, can be used to provide bed-load transport measurements in rivers. The U.S. Army Corps of Engineers-Engineer Research and Development Center (USACE-ERDC) collected acoustic multi-beam topographic data in the Mississippi River near Vicksburg, MS, USA, to measure sediment bed load during the unusually high flows that occurred during May and June of 2011. This topography data, along with data from three other dates that were included for comparison, has been further analyzed to examine the characteristics of bedforms in the channel. Bedform dimensions were strongly affected by position in the channel cross-section, with lower amplitude, shorter length bedforms near the east bank, larger bedforms near the west bank, and much higher amplitudes and greater lengths in the center section of the channel. Superimposed bedforms were found for flows on the falling limb of the 2011 flood hydrograph. Bedform amplitudes and lengths were positively correlated with flow depths, but bedform amplitudes were typically greater and lengths were shorter in comparison to recently developed predictive methods. Best fit power law relationships for bedform amplitude and length will be presented. In addition, topography data from lower, more typical flows are included to illustrate the topographic variation induced by a wide range of discharges.