Comparison of bed form variance spectra within a meander bend during flood and average discharge

Abstract

Time series analysis of streambed elevation in a meander bend along the Congaree River was used to determine the changes in bed form population succeeding a 16-year flood event. Bed forms observed during the flood event had a significantly greater total height variance than bed forms observed at the same location one week later. Variance spectra were computed for a 595 m longitudinal profile. The data indicate that: a) the bed form variance for the flood record is significantly greater for all wavelengths from 5 to 30 m; b) no well-demarcated bed form classes were present during the survey times, pointing to the possible existence of a continuum of bed form sizes rather than well-defined classes; and c) bed forms produced by the flood discharge were rapidly altered as the stage returned toward average level.