As meandering rivers migrate laterally through their floodplains, the growth of individual bends increases the overall length and sinuosity of the channel. Intermittently, meander limbs from different bends migrate into one another causing the river pathway to shorten, in a process termed neck cutoff. Neck cutoffs and their resulting oxbow lakes are observed on meandering river across the globe, and have been the focus of numerous previous studies. Traditional conceptual models generalize the long-term morphologic evolution of neck cutoffs and depict over-simplified, straight planform geometries. However, neck cutoffs on meandering rivers exhibit a range of complex planform geometries resulting in systematic differences in the process dynamics and evolution of cutoffs.
In this presentation, results from detailed field and numerical studies of hydrodynamics and morphologic changes from five neck cutoffs on the White River in central Arkansas are shown, revealing the importance of channel curvature on cutoff dynamics. Using remotely sensed imagery, a global database of over 600 neck cutoff is then utilized to statistically characterize neck cutoffs into four groups based on cutoff centerline curvature. The findings from these studies are used to introduce new conceptual models for neck cutoffs that incorporate the natural planform variability observed around the globe, allowing for improved predictions of meandering river dynamics.