The Demonstration Erosion Control Project (DEC) addressed problems associated with watershed erosion, sedimentation, flooding, and environmental degradation. Initiated by the federal government in 1984, DEC activities were targeted at 17 watersheds comprising 7,600 sq. km within the Yazoo River Basin of northwest Mississippi. These watersheds had suspended sediment yields about three to six times greater than the national average for similar-sized watersheds.

DEC watersheds were plagued with accelerated channel erosion caused by poor watershed management practices and channelization. Stream channels tended to deepen as small waterfalls or knickpoints migrated upstream from the mouths of the larger channels to the upstream end of even the tiniest tributaries. After channel depth exceeded a critical threshold, explosive widening often occurred. Erosion, sedimentation, and changes in streamflow patterns associated with channel incision degrade and destroy fish and wildlife habitats. The DEC project has been renamed the Mississippi Delta Headwaters Project.

Channel bed erosion by upstream progressing knickpoint	DEC low-drop structure used to control bed erosion

 

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Objectives

• Demonstration of a systems approach for stabilizing watersheds suffering from erosion and sedimentation associated with channel incision.

• Research, monitoring, and evaluation of the performance of control measures.

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DEC is conducted through cooperative efforts of several agencies and institutions.

• Construction

U.S. Army Corps of Engineers (CoE), Vicksburg District

U.S. Department of Agriculture (USDA) Natural Resources Conservation Service

• Research, monitoring, and evaluation

USDA Agricultural Research Service National Sedimentation Laboratory

CoE Waterways Experiment Station

Center for Computational Hydroscience and Engineering at the University of Mississippi

U.S. Geological Survey

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Stream corridors respond to inputs of runoff and sediment from upland areas as well as to conditions in the channels themselves. Accordingly a systematic approach is required to diagnose and treat problems associated with watershed degradation due to channel incision. Notable advances in land treatment and soil erosion conservation practices, stable channel assessment, streambank erosion, stream habitat restoration, physical and computational modeling of rivers and watersheds, sediment transport mechanics, and grade control structure design have resulted from NSL research sponsored by DEC.

Eroding channel bank destabilized by bed erosion	Bank protection measures used by DEC

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Completed DEC structures include (approximate)

• 980 minor grade control structures (drop pipes)
• 182 low drop grade control structures
• 9 high drop grade control structures
• 10 flood water retarding structures
• 30.5 km of levees
• 152 km of bank stabilization
• 29.3 km of channel modifications

 

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Contacts of DEC - Technology Transfer Activities

DEC -developed technology is available for transfer to other agencies and institutions in the United States and around the world to address watershed and channel erosion problems as well as enhance the conservation of natural resources.

Selected National Technology Transfer International Technology Transfer Mississippi Technology Transfer