Abstract
This work proposes an expression for the alongshore sediment transport and a one-line type model to analyze the importance that the curvature of the shoreline and the bathymetric contours, and the associated alongshore wave energy gradients have in the evolution of the coastline and in the development of shoreline undulations. This model characterizes the alongshore wave energy gradients by means of the surf zone width variations and does not make any restriction on the shoreline curvature. The shoreline undulations of two different types of coast are investigated: a curvilinear coast in a prograding spit front, and an erosional stretch of coast adjacent to a river mouth. The results for the first one are in good agreement with observations. For the erosional coast good qualitative results are obtained, although a more intensive study is required.
Highlights
This work proposes an expression for the alongshore sediment transport and a one-line type model to analyze the importance that the curvature of the shoreline and the bathymetric contours, and the associated alongshore wave energy gradients have in the evolution of the coastline and in the development of shoreline undulations
Ashton et al (2001) used this mechanism to explain the presence of sand waves on rectilinear coastlines, which are coastline features similar to shoreline undulations, as the result of an instability mechanism based on the coupling between littoral drift and coastal morphology induced by high-angle waves
This work analyzes the influence of shoreline curvature in the morphological evolution of the coastline and the formation of shoreline undulations
Summary
This work proposes an expression for the alongshore sediment transport and a one-line type model to analyze the importance that the curvature of the shoreline and the bathymetric contours, and the associated alongshore wave energy gradients have in the evolution of the coastline and in the development of shoreline undulations. A change in the orientation of the beach planform, as it occurs at the tip of a spit (Figure 1),frequently leads to the development of morphologies such as shoreline undulations (López-Ruiz et al, 2012) These shoreline features have spatial dimensions of 101-103 m and can propagate towards the tip of the spit (Petersen et al, 2008). On Sylt Island in the southern North Sea (Germany) with dimensions of 500-1000 m (Figure 1a); at the spit on the west side of Cape Lookout (North Carolina, USA) with dimensions of 250-1000 m (Figure 1b); at the Arçay Spit (France) with lengths of 500-1000 m (Figure 1c); and at Sandy Hook Spit (New York, USA) with lengths of 1000-2000 m (Figure 1d) Examples of these undulations on the Spanish coast can be found at Doñana (Figure 2), at the mouth of the Guadalquivir Estuary (Gulf of Cádiz). The so called high-angle wave instability (HAWI) mechanism cannot explain the formation of shoreline undulations in the prograding front of the spit. Ashton et al (2001) used this mechanism to explain the presence of sand waves on rectilinear coastlines, which are coastline features similar to shoreline undulations, as the result of an instability mechanism based on the coupling between littoral drift and coastal morphology induced by high-angle waves (offshore waves approaching at an angle greater than 43o with respect to shoreline orientation)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call