EXPERIMENTAL INVESTIGATION OF THE FLOW STRUCTURE AT A CHUTE CUTOFF WITH SIMPLIFIED GEOMETRY

Meandering rivers shorten and straighten their planform through the development of cutoffs. This study investigates the flow structure at a chute cutoff through detailed flow velocity measurements in a physical model with a simplified geometry and an immobile, flat bed. The first configuration of the physical model consists of three consecutive bends with a sine-generated planform and no cutoff channel. The three-dimensional flow structure in the bends was documented using an acoustic Doppler velocimeter at key cross-sections. Surface velocities were measured using particle tracking velocimetry. Following documentation of the flow structure in the bends, a straight cutoff channel was inserted across the neck of the middle bend and the flow measurements were repeated. The results provide insight into the mechanisms responsible for the patterns of morphological change that occur following the development of chute cutoffs.