A unifying framework for shoreline migration: 2. Application to wave-dominated coasts
The Bruun rule, widely used to predict transgression due to sea level rise on decade to century timescales based on a fixed nearshore profile, neglects the influence of inland topography and substrate lithology, leading to physically unreasonable predictions on longer timescales. We use a new approach, the shoreline Exner equation, to model shoreline transgression on wave-dominated coasts over timescales of decades to millennia. Our results show that interactions between nearshore processes and inland topography, neglected by Bruun-style models, drive morphologic evolution which modulates shoreline retreat. Analytical solutions suggest that while short-term shoreline retreat will sometimes follow the Bruun rule, long-term transgression will always follow the slope of the inland topography. Moreover, our results show that the slope of the inland landscape, relative to the nearshore slope, exerts a first-order control on coastal morphology, such that steep coasts tend to form cliff-backed beaches while gentle coasts tend to form barrier island-lagoon systems. However compositional variations between the inland landscape and nearshore system can alter this pattern. Copyright 2009 by the American Geophysical Union.
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- 04 Earth Sciences
Citation
Published In
DOI
EISSN
Publication Date
Volume
Issue
Related Subject Headings
- 41 Environmental sciences
- 37 Earth sciences
- 04 Earth Sciences