Upper Mississippi River Restoration Program Long Term Resource Monitoring

Rates and Patterns of Net Sedimentation From 1997-2017 in Backwaters of Pools 4 and 8 of the Upper Mississippi River

Rogala, J.R., J. Kalas, and R.M. Burdis. 2020. Rates and Patterns of Net Sedimentation From 1997-2017 in Backwaters of Pools 4 and 8 of the Upper Mississippi River. A completion report submitted to the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration Program from the U.S. Geological Survey, LTRM-2018ST4. 23 pp. Location of supporting data: https://doi.org/10.5066/P9D467M3

Abstract

Loss of water depth in backwaters on the Upper Mississippi River (UMR) due to sedimentation is a major concern for river managers as it relates to the suitability of fish and wildlife habitat. In order to gain a better understanding of this issue, net sedimentation rates were obtained for backwaters of the UMR in Navigation Pools 4 and 8 by measuring bed elevation changes along transects between 1997 and 2017. Mean sedimentation rates (cm yr1 ± standard error) in aquatic areas during the 20-yr period were lower than most previously reported rates in backwaters of the UMR, with means of 0.27± 0.06 in Pool 4 and 0.51± 0.08 in Pool 8. Rates were highly variable within backwaters, but generally increased from terrestrial to deeper aquatic portions, with rates highest in areas deeper than 0.5 meter. Rates and loss of depth also varied among transects. These 20-yr estimates provide the most accurate information available on backwater sedimentation dynamics and are invaluable for planning management actions to maintain the viability of the diverse UMR ecosystem.

Keywords

Backwaters; erosion; Mississippi River; sediment transport; sedimentation