Accession Number:

ADA199779

Title:

Biological and Physical Effects of Missouri River Spur Dike Notching

Descriptive Note:

Final rept.

Corporate Author:

ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB

Report Date:

1988-09-01

Pagination or Media Count:

56.0

Abstract:

Since 1975 there has been a program of creating notches or gaps in river training structures along the Missouri River. More than 1,300 notches have been constructed. An additional 20 spur dike training structures located in two reaches of the Missouri River near Omaha were modified using a new notch design. Material excavated from notches was used to construct a small reef just downstream of each notch. Results of semiannual hydrographic surveys of the regions immediately adjacent to 12 of these notch-with-reef structures were analyzed to determine the effects of modification on depths and water surface area. Means and standard deviations of depth adjacent to dikes increased after notching, as did water surface area at a reference stage. Considerable variation in bed response to notch-with-reef construction was observed from dike to dike and between the two reaches studied. In an effort to compare fish use of the notch-with-reef structures with that of other types of training dikes, a study was conducted in one of the above-mentioned reaches. Fish, water quality, current velocity, and bed material were sampled during moderate flow in June and August adjacent to nine spur dikes. Three of the dikes were unmodified, 3 were notched with reefs, and 3 were simply notched. No significant differences were observed among dike types for any of the variables. However, the areas around the dikes are distinctive from the main channel--and much more valuable ecologically.

Subject Categories:

  • Ecology
  • Civil Engineering

Distribution Statement:

APPROVED FOR PUBLIC RELEASE