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Stream Stabilization

Description
Stream corridor stabilization involves controlling down cutting stream beds and shaping, armoring and vegetating vertical, eroding stream banks. Down cutting stream beds are usually controlled by installing riffle-pool systems that stop the advance of "nick points" (vertical drops in the stream bed). Nick points are evidence of a bed that is down cutting. Vertical, bare stream banks are excavated back to a stable slope, which usually requires a bank sloped back 3 horizontal feet for every 1 foot of vertical height.

Once a bank is sloped back it can be vegetated. Deep, rooted native prairie plants are recommended for stream bank vegetation to hold banks in place. Toes of steam banks can be armored with rip rap rock or other measures. Armoring protects the toes of slopes from the bounce in flows associated with runoff from the frequent, small rainfall events that account for the vast majority of annual precipitation.

 

Benefits
Researchers at ISU have documented that 60% to 70% of sediment loading is from stream corridor erosion in some watersheds. Stabilizing eroding stream corridors will reduce sediment loading and phosphorus delivery that is attached to soil eroding from stream banks. In some cases, stabilizing urban stream corridors is needed to protect infrastructure such as sanitary sewers or trails that may be threatened by erosion in the a down cutting bed or an eroding bank. In many cases, habitat enhancement can be done in conjunction with stream corridor stabilization to create or improve a fishery.

 

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