Insights on Coarse Sediment Routing in Tributaries of the Buffalo National River, AR

Abstract

Sediment routing studies are of particular importance to understanding geomorphic changes in fluvial systems. Although tributary-derived sediment inputs serve as primary sources of sediment in main stems, few in-situ studies analyze controls that dictate these inputs. Thus, gravel caliber and provenance variability in major tributaries of the Buffalo National River (BNR) of northwest Arkansas have been analyzed to identify how lithology and basin morphometrics influence tributary gravel routing in a gravel-mantled bedrock stream. Analyses identified significant coarse sediment inputs from 3 of the 4 study tributaries, with basin area and drainage density appearing to be the most influential morphometric controls on tributary sediment routing processes. Additionally, a pilot study on reach-scale gravel movement was conducted in one of the headwater tributaries of the BNR. This RFID project identified that most bedload movements occur in only the largest peak discharge events, with sediment caliber and channel flow patterns influencing localized sediment entrainment. This study better constrains watershed-scale gravel routing patterns and controls in the BNR, which is critical for understanding channel and basin morphology in this ever-changing fluvial system.