The Mississippi River and Ohio River Confluence

The 2011 flood resulted in the operation of the Birds Point-New Madrid Floodway.  Floodway operation altered the sediment transport regime at and downstream of the confluence of the Mississippi River and the Ohio River.  Floodway operation decisions also impacted the execution of operation plans.  Future operation of the floodway will be influenced by system behavior at crevasse points and their method of operation.

The changes in sediment transport, i.e., deposition or erosion of the channel bed, that resulted from floodway operation may have long-term effects on the system, including effects on water levels at the confluence and operational decisions.  A study is needed to evaluate the potential for observed changes in the confluence reach.

Principle tasks to be performed during this study include:

• Develop a medium scale physical model of the confluence reach downstream to Caruthersville, MO.  The model will be used to assess system change due to floodway operation and to evaluate short-term and long-term impacts of this change. 
• Various alternatives of floodway operation will be tested in the model to evaluate their effects on flood stages and system response.
• Perform field data collection to support model development.
• Analyze historic hydrographic surveys to gain understanding of reach dynamics.
• Review geologic and geomorphologic maps of the area.
• Evaluate sediment flux through this reach during the 2011 flood.
• Analyze historic dredging records.
• Develop a report describing the findings of the investigation.