HYDRAULIC WIDTH VARIATION IN MEANDERING RIVER CHANNELS

Meandering in alluvial rivers occurs through processes of erosion along outer banks and deposition of sediment along inner banks. Traditional treatments of meandering rivers assume an equilibrium between rates of erosion and deposition, resulting in a constant channel width as rivers migrate through their floodplains. However, most natural rivers exhibit spatial and temporal variability in cross-sectional width. By examining the local variability among different meandering rivers and the relationships between parameters that influence morphology, insights can be gained into the process dynamics and planform evolution of meandering rivers at differing scales and environments. This study includes the extraction of high-resolution bathymetric data into cross sections, and delineation of river banklines from aerial photography. Steady flow conditions were modeled using the Army Corps of Engineers program HEC-RAS, and hydraulic widths at varying discharges were extracted. Additionally, channel curvature and spectral analysis were completed using MatLab. Preliminary results from three rivers are presented: the Amite River, LA; Wabash River, IL; and White River, AR. Through application of this methodology to numerous rivers, this research hopes to address the relationships among curvature, slope, migration rates, and variation in hydraulic widths among rivers exhibiting differences in width to depth ratios, scales, and geographic locations.