Degree
Doctor of Philosophy (PhD)
Department
Geography and Anthropology
Document Type
Dissertation
Abstract
Meander cutoffs are pivotal events in the life cycle of rivers, abruptly adjusting flow fields and reshaping riparian environments. The consequences of cutoffs extend beyond geomorphology, influencing aquatic ecosystems, sediment storage within the floodplain, nutrient and contaminant cycling, and risks to human infrastructure. Yet, research of cutoffs has not produced a clear conceptual understanding of the persistence of oxbow lakes, and the dynamics of post-cutoff planform change that aligns with the observations of cutoff events on a global scale. This research aims to use satellite imagery to further clarify our understanding of the post-cutoff morphometrics and processes that constrain the persistence of oxbow lakes, the migration of neck cutoff bends, and the terrestrialization of the post-neck cutoff channels.
A global dataset of 218 cutoff events documented within four decades of Landsat imagery was used to study the terrestrialization of abandoned channels and track active channels following cutoff. Results show that in the first 10 years after cutoff, chute cutoffs infill with sediment and terrestrialize at twice the rate of neck cutoffs, and the distance of the active channel from the abandoned channel was greater for neck cutoffs. The difference between the two styles of cutoff is novel and suggests for the first time that migration of the active channel following cutoff is a key control on oxbow sedimentation. From that larger dataset, 137 neck cutoffs were further analyzed for migration of their post-cutoff bends. Results show that most neck cutoffs result in high curvature bends, migration of the post-cutoff bend is over six times greater than the average migration of the reach, and the style of migration is influenced by the maximum curvature of the cutoff bend. A detailed analysis of six neck cutoffs using high resolution Planet-imagery showed sedimentation locations are influenced by inherited flow, and the length ratio and curvature of the cutoff bend influence the cutoff bar shape.
The results of this study serve to adjust and refine the classical models used to describe post-cutoff sedimentation and planform morphology, highlighting cutoffs as dynamic, fundamental processes that reshape meandering rivers, govern oxbow lifespans, and influence floodplain evolution.
Date
11-2-2025
Recommended Citation
Shoemaker, Dylan T., "Dynamics of Meandering River Cutoffs and Post-Cutoff Sedimentation" (2025). LSU Doctoral Dissertations. 6948.
https://repository.lsu.edu/gradschool_dissertations/6948
Committee Chair
Kory Konsoer