|Shields Jr, Fletcher|
Submitted to: Management of Landscapes Disturbed by Channel Incision Stabilization Rehabi
Publication Type: Proceedings
Publication Acceptance Date: 1/15/1997
Publication Date: N/A
Citation: N/A Interpretive Summary: Channel downcutting is a problem throughout the hill lands that border the Mississippi River valley from Mississippi to Iowa to Illinois. Water quality problems have accompanied the sediment problems associated with channel incision and erosion. A federal interagency project (Demonstration Erosion Control Project in the Yazoo Basin) begun in 1984 in Mississippi has demonstrated many channel stability measures which can help solve these problems. This study discusses the water quality problems and how many of the construction measures being implemented to stabilize the region are also resulting in water quality improvements at no extra cost. Small impoundments, field scale grade control devices and created habitats can improve water quality. Our nation's surface water quality is a concern to all; federal and state water resources managers and regulatory agencies as well as individual farmers can benefit from these results.
Technical Abstract: A federal interagency demonstration project focusing on channel erosion was begun in 1984 in the loess hill lands of northwestern Mississippi. The major objective was developing stabilization/rehabilitation technology in 15 watersheds impacted by erosion and sedimentation associated with channel incision. Suspended sediment yields averaged about 1,000 t km**-2-yr**-2. Stream channels were typically straight due to past channelization, enlarged by erosion, and had scarce woody debris, pool habitat, or stable substrate. Initial efforts focused on acute problems such as flooding, bridge failures, and later, included water quality and aquatic habitat improvement measures. Common measures included field-scale grade control pipes, stream grade controls, bank protection, and floodwater-retarding reservoirs. Observed declines in water quality were temporary and generally associated with storm-generated runoff. Sediment and coliforms trends were shaped by runoff-related watershed processes while phosphorus and nitrogen concentrations were highly influenced by a municipality. Field-scale grade controls and sediment retention ponds processed sediment and nutrients and created wetland and open water habitats used by all classes of vertebrates.