Collaborative Research: Unraveling the Controls on the Origin and Environmental Functioning of Oxbow Lakes

As meandering rivers move through their floodplains, they eventually intersect themselves to remove a portion of the channel. That channel segment can exist as a water body, called an oxbow lake, or become filled with sediment. The ability to predict whether a segment will transform into an oxbow holds significant importance, given that these lakes serve as repositories for pollutants and provide unique habitats. During the initial stages following cutoff, the geometry of the connection is decisive in determining how oxbow evolution plays out. Notably, cutoffs with high-angle junctions tend to accumulate sediment at the entrance, initiating oxbow formation. To evaluate the idea that the initial cutoff geometry determines the likelihood of oxbow formation, the researchers will undertake a comprehensive analysis of recent cutoffs in the West Fork White River (Indiana, USA). They will employ both field data collection and numerical modeling methodologies. Furthermore, collaboration with the Indiana Department of Environmental Management will enable estimates of pollutant storage within oxbows. Additionally, partnerships with the Indy Water Connection Camp and the Williams Summer Science Program will facilitate experiential learning opportunities for local students. Once a meander cutoff occurs, it establishes a bifurcation with the primary river channel. The stability of this bifurcation determines whether it ultimately transforms into an oxbow lake. If the bifurcation is unstable and rapidly fills with sediment, the formation of an oxbow lake becomes more probable. To investigate the role of initial bifurcation geometry in facilitating sedimentary plugging and oxbow development, the project will focus on cutoffs on the West Fork of the White River in Indiana. Various tools, including multibeam bathymetry, sub-bottom profiling, and sediment core analysis, will be employed to assess the geometry and chronology of sediment fill. Subsequently, these data will be utilized in morphodynamic models that simulate the evolution of bifurcations following a cutoff event. The presence of different bifurcation geometries will allow the researchers to model and evaluate how specific geometric configurations lead to accelerated sediment plugging and subsequent oxbow formation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.