Woody Vegetation Protects Streambank Stability during the 1993 Flood in Central Kansas

ABSTRACT:

Streambank changes after the Kansas flood of 1993 were examined using aerial photography to determine the relationship of streambank stability to natural riparian vegetation, stream channel morphology, and soil type. The flooding event that occurred that summer along river courses in the central plains area of the United States was considered in the magnitude of a 100–500 year category. Water flooded riverbanks and farmlands for a two month period in the summer. Lateral streambank erosion was related significantly to vegetative cover and soil types; erosion was greatest on cropland and minimal on the forested streambanks and greater on sandy than on silty soils. Channel position or the interaction of soils with cover type or channel position did not influence lateral erosion, but the interaction of channel position with cover type was significant. Stream characteristics of radius of curvature, width, and ratio of radius to width did not influence erosion. The flood was so large that the water flowed over the banks for great distances much of the time, masking the dynamic effect of water at various channel positions.