FIELD DOCUMENTATION OF OXBOW LAKE FORMATION AT AN EVOLVING CHUTE CUTOFF ON THE WABASH RIVER, IL-IN

Chute cutoffs are a common feature of meandering rivers worldwide. Chute cutoffs play a role in the dynamic equilibrium of the long term planform morphology of a river by shortening and straightening the river channel. Cutoffs also influence floodplain sedimentation through oxbow lake formation and filling. Given their influence on channel planform morphology as well as floodplain sedimentation dynamics, an understanding of the underlying processes governing oxbow lake formation is of central importance. In this paper, we present field documentation of a recent chute cutoff on the Wabash River, IL-IN. Our methods include repeated hydroacoustic measurements of three-dimensional flow velocity and bed elevation at the upstream and downstream ends of the chute cutoff, as well as GPS surveys of channel banklines and aerial photograph analysis. Based on these observations we present a conceptual model for the co-evolution of flow structure and channel morphology during oxbow lake formation.