A Stream Restoration Plan for the City of Davenport
Matthiesen, Ed A.
Spector, D. F.
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The City of Davenport, Iowa, is drained by two major stream systems - Duck Creek and Blackhawk Creek – and a network of smaller streams and open channels. As urbanization increases these streams are experiencing significant and continued erosion due to extreme swings in storm flows. These flows have caused stream bank failures and channel head cutting, resulting in sediment and brush in the channel, loss of park land and residential property, threats to infrastructure such as park trails, and bridge and culvert plugging. It is expected that future water quality impairments such as turbidity and biotic impairment in the creeks will have to be addressed by the City as the MS4 permit holder. Davenport is located in the eastern side of Iowa on the Mississippi River in the Quad Cities area, which has a combined population of about 380,000. This project developed a stream restoration plan for 18 miles of public and private stream channel using standardized construction details to develop construction level plans and project priorities for the entire channel length. The project was completed using a rapid visual assessment of all channel reaches. The channels were walked by a team who recorded conditions and estimated channel bank recession rate according to a method developed by the Natural Resource Conservation Service. The team compiled a photographic record and field records of proposed remedial actions. At selected locations, a Rosgen Bank Erosion Hazard Index was calculated, bank pins and channel chains were installed and a cross section measured using a GPS unit. A hydrologic/ hydraulic model was also constructed using the EPA SWMM model to estimate channel velocities and shear stress and to assist in developing planning standards for undeveloped land.