|Shields Jr, Fletcher|
Submitted to: International Conference on Water Resources Engineering Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/10/1998
Publication Date: N/A
Interpretive Summary: Many streams in agricultural watersheds are characterized by unstable channel boundaries. Erosion in these unstable channels not only destroys valuable agricultural land, but also degrades the habitat for fish and other aquatic organisms. Bank protection measures have the potential to preserve valuable agricultural lands and enhance aquatic habitats. A laboratory study was conducted to improve the design of spur dikes (a structure widely used to protect stream banks) to not only protect the stream banks, but also to maximize the volume of the scour pool formed by the structure. Stable pools are an important part of improving aquatic habitats in unstable stream channels. It was found that spur dikes constructed with an angle of 135 degrees to the bank had the most potential benefit to aquatic habitat and the best potential for protection of the banks. This type of information is needed by managers concerned with agricultural watersheds.
Technical Abstract: Volumes of the scour hole in the vicinity of model spur dikes were measured in a laboratory flume under clear-water overtopping flows. Angles of 45, 90 and 135 degrees were used with contraction ratios of 0.125 and 0.250. These experiments were undertaken to optimize the design of spur dikes to enhance aquatic habitats and maintain protection of stream banks. Results showed that of the three angles tested, spur dikes with angles of 135 degrees caused the least potential for erosion of the bank and caused the greatest volume of local scour which would maximize potential benefits to aquatic habitats.