A NEW CONCEPTUAL MODEL FOR NECK CUTOFFS REVEALED BY HIGH-RESOLUTION BATHYMETRIC DATASETS (Invited Presentation)

Neck cutoffs and their resultant oxbow lakes are important and prominent features of riverine landscapes. Detailed field-based research focusing on the morphologic evolution of neck cutoffs is currently insufficient to fully characterize neck cutoff evolution. High-resolution bathymetric data were collected over three years for the purpose of determining channel morphology and morphologic change on three actively evolving neck cutoffs. Here we present results from these detailed field surveys, and summarize the findings into a new conceptual model for neck cutoffs. Channel planform geometry and location of cutoff in relationship to the bend were found to have a substantial impact on the morphodynamics of the cutoffs. The findings of this research are also combined with recent analyses of the three-dimensional flow structure through neck cutoffs to provide a mechanistic explanation for the morphodynamics of neck cutoffs.