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In this study progradation of the dune toe on the sandy, dune-backed beaches of Makah Bay, on the Pacific Ocean shorelines of the reservation lands of the Makah Tribe, were documented for the first time. A shoreline assessment was implemented that included repeat beach profile surveys using RTK-DGPS and aerial lidar, and historical change analysis using aerial photos. Analysis of GNSS and aerial lidar suggest patterns of dune toe progradation over the last decade at average rates of ~0.8 m/yr between 2010 and 2022 over almost all the 5.5 km length of beach in Makah Bay, excepting the ~250m long erosional area that prompted the study. A beach vegetation line delineated in aerial photos collected between 1952 and 2019 moved seaward at average rates of ~0.7 m/yr across the entire length of Makah Bay, suggesting that the pattern of progradation is long-lived. We assess evidence to evaluate whether this pattern of dune progradation can be explained by sediment supplies from watersheds draining to Makah Bay and conclude that local sediment supply cannot explain observed patterns. A variety of shoreline processes associated with relative sea-level fall are discussed and may explain the observed rates of shoreline progradation.
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Exploring Marine and Aeolian Controls on Coastal Foredune Growth Using a Coupled Numerical Model
Coastal landscape change represents aggregated sediment transport gradients from spatially and temporally variable marine and aeolian forces. Numerous tools exist that independently simulate subaqueous and subaerial coastal profile change in response to these physical forces on a range of time scales. In this capacity, coastal foredunes have been treated primarily as wind-driven features. However, there are several marine controls on coastal foredune growth, such as sediment supply and moisture effects on aeolian processes. To improve understanding of interactions across the land-sea interface, here the development of the new Windsurf-coupled numerical modeling framework is presented. Windsurf couples standalone subaqueous and subaerial coastal change models to simulate the co-evolution of the coastal zone in response to both marine and aeolian processes. Windsurf is applied to a progradational, dissipative coastal system in Washington, USA, demonstrating the ability of the model framework to simulate sediment exchanges between the nearshore, beach, and dune for a one-year period. Windsurf simulations generally reproduce observed cycles of seasonal beach progradation and retreat, as well as dune growth, with reasonable skill. Exploratory model simulations are used to further explore the implications of environmental forcing variability on annual-scale coastal profile evolution. The findings of this work support the hypothesis that there are both direct and indirect oceanographic and meteorological controls on coastal foredune progradation, with this new modeling tool providing a new means of exploring complex morphodynamic feedback mechanisms.
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- PAR ID:
- 10125135
- Date Published:
- Journal Name:
- Journal of Marine Science and Engineering
- Volume:
- 7
- Issue:
- 1
- ISSN:
- 2077-1312
- Page Range / eLocation ID:
- 13
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/jmse7010013
