Incorporating flowpaths as an explicit measure of river-floodplain connectivity to improve estimates of floodplain sediment deposition
Date
2024-05-28
Journal Title
Journal ISSN
Volume Title
Publisher
Geomorphica
Abstract
Variation in floodplain topography can lead to gradual flooding and increase river-floodplain connectivity. We show that incorporating flowpaths as an explicit measure of river-floodplain connectivity can improve estimates of floodplain sediment deposition. We focus on the floodplain of the South River, downstream of Waynesboro, Virginia, where measurements of mercury accumulation have been used to estimate decadal-scale sedimentation rates. We developed a two-dimensional Hydrologic Engineering Center's River Analysis System (2D HEC-RAS) hydrodynamic model and used simulated model results with sediment deposition data to create regression models describing sedimentation across the floodplain. All of our statistical models incorporated a flowpath length from the location on the floodplain downstream to the riverbank as an explicit measure of river-floodplain connectivity that improved our estimates of floodplain sediment deposition (r2 = 0.514). We applied our best regression model to our hydrodynamic model results to create a map of floodplain sedimentation rate and discuss differences of three separate sections of floodplain. We found that floodplains with variable topography had wider, bimodal probability distribution functions (PDFs) of sedimentation rate (aggregated spatially) than floodplains without this topographic relief (with narrower log-normal PDFs). Our work highlights how floodplain topography and river-floodplain connectivity affect sedimentation rates and can help inform the development of floodplain sediment budgets.
Description
This article was originally published in Geomorphica. The version of record is available at: https://doi.org/10.59236/geomorphica.v1i1.25. Copyright (c) 2024 Sumaiya Sumaiya, John T. Schubert, Jonathan A. Czuba, James E. Pizzuto
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/)
Keywords
2D HEC-RAS, floodplain sedimentation, floodplain topography, mercury contamination, river-floodplain connectivity
Citation
Sumaiya, S., Schubert, J. T., Czuba, J. A., & Pizzuto, J. E. (2024). Incorporating flowpaths as an explicit measure of river-floodplain connectivity to improve estimates of floodplain sediment deposition. Geomorphica, 1(1). https://doi.org/10.59236/geomorphica.v1i1.25