Exploring the Potential for Conservation Lands in Middle Mississippi River Floodplains to Mitigate Flood Flows for Ecosystem Services Active
Reconnection of floodplains to their rivers has been considered a fundamentally beneficial ecological practice.
Providing room for floods to expand has also been considered useful in increasing social and ecological resilience to flood disturbances. Implementation of connectivity projects in heavily engineered rivers, however, can be complex and optimization requires a comprehensive understanding of the underlying physical processes. This project explores the physical processes of floodplain connectivity on the Middle Mississippi River and addresses options that may increase ecosystem services associated with connectivity. The research is an interdisciplinary collaboration among the USGS-University of Missouri Cooperative Fish and Wildlife Research Unit, the School of Earth Systems and Sustainability, Southern Illinois University, and the River Studies Branch, USGS, Columbia Environmental Research Center.
Addressing the issue:
The location for our study is the Wilkinson Island Unit of the Middle Mississippi National Fish and Wildlife Refuge (fig. 1). Refuge managers indicated that they had concerns about where and when the unit flooded, how flooding could be related to nutrient and carbon processing in the unit, and whether there were engineering alternatives that could correct excessive overbank sedimentation in the upstream third of the unit.
We developed a high-resolution 2-dimensional hydrodynamic model for the channel and floodplain, calibrated the model with measured water-surface elevations from boat surveys and pressure transducers, and validated the model with acoustic Doppler current profiler (ADCP) data.
We used the model to evaluate when and where the unit floods -- especially to assess when the unit backfloods from downstream connections compared to upstream overbank flooding -- and the effects on provision of floodplain habitats (fig. 2). We also evaluated the ability of two deflection levee configurations (a short berm and a long berm) to alter flooding, shear-stress distributions, and sedimentation (fig. 3).
Future steps:
The research team has completed calibration and evaluation of the 2-dimensional hydrodynamic model. We ran the 2-dimensional modeling for the existing conditions, two deflection levee scenarios, and over a relevant range of overbank discharges. A final report, journal article, and data release will be completed in FY 2022. The results are also being used in extensions to evaluating nutrient processing and the interactions between surface and groundwater.
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- Overview
Reconnection of floodplains to their rivers has been considered a fundamentally beneficial ecological practice.
Sources/Usage: Public Domain. View Media Details(fig. 1) Location of the Wilkinson Island Unit in the Middle Mississippi River. Providing room for floods to expand has also been considered useful in increasing social and ecological resilience to flood disturbances. Implementation of connectivity projects in heavily engineered rivers, however, can be complex and optimization requires a comprehensive understanding of the underlying physical processes. This project explores the physical processes of floodplain connectivity on the Middle Mississippi River and addresses options that may increase ecosystem services associated with connectivity. The research is an interdisciplinary collaboration among the USGS-University of Missouri Cooperative Fish and Wildlife Research Unit, the School of Earth Systems and Sustainability, Southern Illinois University, and the River Studies Branch, USGS, Columbia Environmental Research Center.
Addressing the issue:
The location for our study is the Wilkinson Island Unit of the Middle Mississippi National Fish and Wildlife Refuge (fig. 1). Refuge managers indicated that they had concerns about where and when the unit flooded, how flooding could be related to nutrient and carbon processing in the unit, and whether there were engineering alternatives that could correct excessive overbank sedimentation in the upstream third of the unit.
Sources/Usage: Public Domain. View Media Details(fig. 2) Model domain for the Wilkinson Island hydrodynamic model. Green arrows indicate downstream to upstream flooding. Red arrows indicate upstream to downstream. We developed a high-resolution 2-dimensional hydrodynamic model for the channel and floodplain, calibrated the model with measured water-surface elevations from boat surveys and pressure transducers, and validated the model with acoustic Doppler current profiler (ADCP) data.
We used the model to evaluate when and where the unit floods -- especially to assess when the unit backfloods from downstream connections compared to upstream overbank flooding -- and the effects on provision of floodplain habitats (fig. 2). We also evaluated the ability of two deflection levee configurations (a short berm and a long berm) to alter flooding, shear-stress distributions, and sedimentation (fig. 3).
Sources/Usage: Public Domain. View Media Details(fig. 3) Flooding extent and depths for a 6.5% daily exceedance flood for the existing condition and for the short-berm deflection levee (black line) scenarios. Future steps:
The research team has completed calibration and evaluation of the 2-dimensional hydrodynamic model. We ran the 2-dimensional modeling for the existing conditions, two deflection levee scenarios, and over a relevant range of overbank discharges. A final report, journal article, and data release will be completed in FY 2022. The results are also being used in extensions to evaluating nutrient processing and the interactions between surface and groundwater.
Return to Large River Ecology, Restoration, and Management
Return to River Studies