Mississippi Valley Division Engineer Research and Development Center

Merriwether – Cherokee Potamology Study

Mississippi River Geomorphology and Potamology Report No. 9

During the historic flood of 2011, the Mississippi River reached record-breaking water

levels between Cairo, IL, and Memphis, TN. Downstream from Tiptonville, TN, Sheep 

Ridge Road Spur Levee (private) was overtopped and crevassed when the Mississippi 

River reached a stage of 48.35 feet (ft) on the Tiptonville gage. The length of spur levee 

crevassed was 3,000 ft, and the length of bankline eroded was 2,700 ft. As a result, the 

Mississippi River began to form a new cutoff from river mile 869 to 860. Erosion 

extended approximately 4,000 ft along Island 13, degrading the landscape to elevations 80 

feet below natural ground. The crevasse divided the Sheep Ridge Road Spur Levee, 

leaving an approximate 3,000 ft section to the east of the crevasse (eastern spur levee) and 

an approximate 2.2-mile section to the west of the crevasse of Sheep Ridge Road Spur 

Levee (the western spur levee). The eastern spur levee is connected to the mainline 

Tiptonville–Obion River Levee. 

A concern was that without modification of the western spur levee and Island 13 overbank, 

the Mississippi River would continue to form a 9-mile cutoff. If a cutoff were to form, 

potential adverse impacts included the following: changes in long-term reach dynamics, 

navigation outdraft conditions, increased dredging operations, hydrodynamic condition 

changes in close proximity to a Mississippi River Levee mainline levee (Tiptonville-Obion 

River Levee), endangerment of existing channel improvement features ($60M), 

endangerment of completed crevasse repairs ($27M), and endangerment of planned 

crevasse repairs.

The Merriwether-Cherokee Potamology Study report documents the following analyses: 

infrastructure, Low Water Reference Plane, thalweg and tertiary layer, volumetric, 

specific gage, duration, multi-dimensional modeling, one-dimensional modeling, and a 

navigation assessment.

Multi-dimensional model domain surface
Points of Contact

Brian M. Hall, P.E. 

Author

USACE MVM

Brian.M.Hall@usace.army.mil

Freddie Pinkard

MRG&P Sr. Program Manager

USACE MVK

Freddie.Pinkard@usace.army.mil

Ty V. Wamsley, Ph.D.

MRG&P Technical Director

USACE MVD

Ty.V.Wamsley@usace.army.mil

For More Information

To access the full version of Merriwether-Cherokee Potamology Study report, click the following link: https://erdclibrary.erdc.dren.mil/xmlui/handle/11681/22562

Additional MRG&P reports, historic reports, and MRG&P information can be accessed from the MRG&P Publications 

and Technology Transfer website:

http://www.mvd.usace.army.mil/Missions/MississippiRiverScienceTechnology/MSRiverGeomorphologyPotamology/

PublicationsTechTransfer.aspx.

Summary of Significant Findings

• The study results indicated that there is a moderate risk for cutoff 

formation. Dense vegetation on the entire Island 13 overbank 

was recommended to mitigate the long-term risk of cutoff 

formation. Short-term risk mitigation measures are required until 

mature vegetation across entire overbank is established.

• The analysis indicated a severe risk for local scour at the closure 

structure. Local scour countermeasures were evaluated and 

recommended for implementation.

• The navigation analysis indicated a potential for an outdraft 

condition at the study crevasse.

• The analysis indicated scour potential at the toe of the Tiptonville–

Obion River Levee. It is recommended that further investigation 

be conducted on the scour potential to determine if MRL 

protection measures are required.

Island 13 overbank crevasse post 2011 flood. Multi-dimensional model island 13 overbank 

features.