CURVES, CONFLUENCES, AND CUTOFFS: MORPHODYNAMIC INSIGHTS FROM THE WABASH RIVER

The Wabash River is ~800 km long and drains more than 100,000 km² of central Indiana and eastern Illinois. Over the past 12 years, a series of research projects has examined the dynamics of confluences, bends, and cutoffs along the Wabash River – one of the largest unregulated meandering rivers in the United States. These process-based studies have revealed many new insights into the dynamics of meandering rivers, including 1) feedbacks between three-dimensional flow structure, near-bank large woody debris, and rates and patterns of bank erosion, 2) mean and turbulent flow characteristics at channel confluences, including confluent meander bends, and the relation of flow characteristics to confluence morphology, 3) characteristics of three-dimensional flow and planform adjustment in elongate meander loops, and 4) interaction between channel form and flow structure in evolving chute cutoffs. These studies also show how external forcings, including variations in discharge, backwater effects, partial bedrock exposure, and variability in geotechnical properties of the floodplain, influence the dynamics of the Wabash River. The presentation summarizes and synthesizes key findings from over a decade of ongoing research on a large, mixed bedrock-alluvial meandering river, and suggests directions for future research.