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Flow regime, sediment supply and base level control geometry and evolution of alluvial channels and floodplains. Single thread rivers subject to constant forcing can reach equi-librium conditions in which the amount of sediment deposited on the floodplain through point bar deposition and overbank sedimentation is balanced by erosion of floodplain sed-iment through channel migration. At equilibrium, floodplain slope and sediment size dis-tribution, reach-averaged channel geometry (width and depth) and channel migration rates do not change in time. In response to changes in sediment supply and floodplain width, channel geometry and migration rate, floodplain slope and size distribution are expected to evolve in space and time. Predicting this response remains an open problem for geoscien-tists and engineers. Here we use an equilibrium solution of a 1D morphodynamic frame-work of channel-floodplain evolution to investigate how equilibrium conditions change as a function of sediment supply and floodplain width. Sediment is modeled here as a mix-ture of two grain sizes, sand and mud. Channel migration rate and width are functions of near-bank flow properties and floodplain characteristics. We zero the model using input parameters based on the pre-1930 ~ reach of the Minnesota River from Mankato to Jordan, USA, where data is available for proper field scale model verification. We then use the validated model to quantify the long-term (equilibrium) response of the schematic reach to changes in sediment supply magnitude and size distribution, as well as to changes in floodplain width.
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The Power of Environmental Observatories for Advancing Multidisciplinary Research, Outreach, and Decision Support: The Case of the Minnesota River Basin
Abstract Observatory‐scale data collection efforts allow unprecedented opportunities for integrative, multidisciplinary investigations in large, complex watersheds, which can affect management decisions and policy. Through the National Science Foundation‐funded REACH (REsilience under Accelerated CHange) project, in collaboration with the Intensively Managed Landscapes‐Critical Zone Observatory, we have collected a series of multidisciplinary data sets throughout the Minnesota River Basin in south‐central Minnesota, USA, a 43,400‐km2tributary to the Upper Mississippi River. Postglacial incision within the Minnesota River valley created an erosional landscape highly responsive to hydrologic change, allowing for transdisciplinary research into the complex cascade of environmental changes that occur due to hydrology and land use alterations from intensive agricultural management and climate change. Data sets collected include water chemistry and biogeochemical data, geochemical fingerprinting of major sediment sources, high‐resolution monitoring of river bluff erosion, and repeat channel cross‐sectional and bathymetry data following major floods. The data collection efforts led to development of a series of integrative reduced complexity models that provide deeper insight into how water, sediment, and nutrients route and transform through a large channel network and respond to change. These models represent the culmination of efforts to integrate interdisciplinary data sets and science to gain new insights into watershed‐scale processes in order to advance management and decision making. The purpose of this paper is to present a synthesis of the data sets and models, disseminate them to the community for further research, and identify mechanisms used to expand the temporal and spatial extent of short‐term observatory‐scale data collection efforts.
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- Award ID(s):
- 1209402
- PAR ID:
- 10453998
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Water Resources Research
- Volume:
- 55
- Issue:
- 4
- ISSN:
- 0043-1397
- Page Range / eLocation ID:
- p. 3576-3592
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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