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Abstract High‐resolution topography reveals that floodplains along meandering rivers in Indiana commonly contain intermittently flowing channel networks. We investigated how the presence of floodplain channels affects lateral surface‐water connectivity between a river and floodplain (specifically exchange flux and timescales of transport) as a function of flow stage in a low‐gradient river‐floodplain system. We constructed a two‐dimensional, surface‐water hydrodynamic model using Hydrologic Engineering Center's River Analysis System (HEC‐RAS) 2D along 32 km of floodplain (56 km along the river) of the East Fork White River near Seymour, Indiana, USA, using lidar elevation data and surveyed river bathymetry. The model was calibrated using land‐cover specific roughness to elevation‐discharge data from a U.S. Geological Survey gage and validated against high‐water marks, an aerial photo showing the spatial extent of floodplain inundation, and measured flow velocities. Using the model results, we analyzed the flow in the river, spatial patterns of inundation, flow pathways, river‐floodplain exchange, and water residence time on the floodplain. Our results highlight that bankfull flow is an oversimplified concept for explaining river‐floodplain connectivity because some stream banks are overtopped and major low‐lying floodplain channels are inundated roughly 19 days per year. As flow increased, inundation of floodplain channels at higher elevations dissected the floodplain, until the floodplain channels became fully inundated. Additionally, we found that river‐floodplain exchange was driven by bank height or channel orientation depending on flow conditions. We propose a conceptual model of river‐floodplain connectivity dynamics and developed metrics to analyze quantitatively complex river‐floodplain systems.
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This content will become publicly available on April 1, 2026
James Buttle Review: Bed, Banks and Beyond: River Flood Dynamics
Floods are amplified and attenuated by features and processes across spatial scales, defined here as flood dynamics. We review and synthesise these influences at the catchment, river network and reach scales as a means of integrating understanding of controls on flood dynamics and identifying key questions that arise because of differences in techniques of investigation and disciplinary emphases between spatial scales. Catchment‐scale influences include catchment area, topography, lithology, land cover, precipitation, antecedent conditions and human alterations such as changing land cover. Network‐scale influences on flood dynamics include network topology, longitudinal variations in the geometry of successive river corridor reaches, lakes and wetlands and human alterations including flow regulation and cumulative changes in channel‐floodplain connectivity in multiple reaches across a network. Reach‐scale influences on flood dynamics include water sources, river corridor geometry and connectivity and human alterations such as artificial levees, channelisation, bank stabilisation, changes to floodplain land cover and drainage, dike operation, process‐based river restoration and urban stormwater management. Our review and synthesis of relevant literature suggest that the relative importance of these multiple influences on flood dynamics varies across spatial scales. Hillslope response may dominate hydrograph characteristics in smaller catchments, for example, whereas network geometry and flow dynamics exert progressively stronger influences on flood dynamics with increasing catchment size. Scale‐specific advances in understanding flood dynamics, including rainfall‐runoff analyses of water movements from uplands into channel networks (catchment‐scale), analyses of flow dynamics along networks of multiple channel reaches (network‐scale) and investigations of biophysical feedbacks and the influences of river corridor geometry and hydraulic roughness (reach‐scale), have largely contributed to understanding flood dynamics, but there remain important disconnects between these diverse bodies of research and outstanding questions related to the cumulative effects on flood dynamics across scales.
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- Award ID(s):
- 2142761
- PAR ID:
- 10595298
- Publisher / Repository:
- Hydrological Processes
- Date Published:
- Journal Name:
- Hydrological Processes
- Volume:
- 39
- Issue:
- 4
- ISSN:
- 0885-6087
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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