Modeling Reach Scale Response to Regulated Flows on the Willamette River
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Date
2022-02-18
Authors
Webster, Dion
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
The upper Willamette river was historically a multi-threaded gravel-bed river. The multidecadal effects of a reduced flow regime, sediment flux, recruitment of large woody debris and bank stabilization caused by anthropogenic disturbances have resulted in decreased riverscape complexity. This project incorporates a 2D hydrodynamic landscape evolution model to simulate the extent of functional floodplain and the erosion/deposition patterns associated with the functional flow event for a segment of the upper Willamette River. The functional floodplain simulation indicated secondary features with tall banks and majority of the geomorphic change occurring in the main channel and adjacent bars rather than the floodplain features. Compared to a previous study on potential 2-year flood extent, the contemporary functional floodplain is drastically smaller. Modeling results show high precision values for inundation and a need for more erosion/deposition validation data. Results from this study also advocate for the inclusion of more landscape evolution model simulations for future restoration efforts.
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Keywords
Fluvial geomorphology, Geomorphology