|Shields Jr, Fletcher|
Submitted to: Management of Landscapes Disturbed by Channel Incision Stabilization Rehabi
Publication Type: Proceedings
Publication Acceptance Date: 1/5/1998
Publication Date: N/A
Interpretive Summary: Streams in many agricultural watersheds are unstable and experience accelerated erosion and sediment deposition. Cost-effective strategies to restore stream channel stability and ecological resources are needed. Previous research has shown that longitudinal stone toe (a ridge of stone) placed along steep, eroding channel banks is one of the most reliable, cost-effective bank stabilization structures available. However, aquatic habitats associated with stone toe are generally inferior to that provided by stone spur dikes. This study tested a design that combined attractive features of stone toe and spurs by adding about 16% more stone to existing toe structures. Only modest changes in water depth and width resulted, but overall habitat quality improved. Fish populations responded more strongly than physical variables, shifting away from a structure typical of degraded habitats dominated by large numbers of small forage fish toward one more typical of less degraded conditions that included larger game fish. This research shows state and federal resource managers that aquatic habitat restoration objectives may be met when placing stone toe with minor additional cost.
Technical Abstract: Longitudinal stone toe is one of the most reliable and economically attractive approaches for stabilizing eroding banks in incised channels. However, aquatic habitat provided by stone toe is inferior to that provided by spur dikes. In order to test a design that combined features of stone toe and spurs, eleven stone spurs were placed perpendicular to 170 m of existing stone toe in Goodwin Creek, Mississippi. Response was evaluated by monitoring fish and habitats in the treated reach and an adjacent comparison reach (standard toe without spurs) over four years. Furthermore, physical habitat within the treated reach was compared with seven reaches protected with standard toe on a single date three years after construction. Overall results indicated that spur addition resulted in modest increases in baseflow stony bankline, water width and pool habitat availability, but had only local effects on depth. These relatively small changes in physical habitat were accompanied by major shifts in fish species composition away from a run-dwelling assemblage dominated by large numbers of cyprinids and immature centrarchids toward an assemblage containing fewer and larger centrarchids.