Periodic Shoreline Morphology, Fire Island, New York

Abstract

Abstract:The presence of shoreline undulations along the Atlantic coast of Fire Island, NY requires careful consideration in developing erosion control and hurricane protection plans and design alternatives for the protection of the Fire Island barrier and the Long Island mainland. An analysis and geometric characterization of these morphologic shoreline features revealed that the magnitude of the shoreline undulations approximates typical protective berm design widths and exceeds typical advance nourishment beach widths. Because shoreline undulations are natural morphologic features of the Fire Island shoreline their presence after project construction must be anticipated. Conclusions drawn from the analysis of the Fire Island shoreline undulations indicate that the design berm width could be compromised well before scheduled renourishment if explicit consideration of shoreline undulations is not included in the development of the design cross-section.

Decoupling processes and scales of shoreline morphodynamics

“…However, there is little evidence of alongshore propagation of pulses of sediment at Fire Island (Fig. 2), in agreement with our CEOF analysis and findings by Gravens (1999), with the exception of the time period from approximately 1994 to 2002. The oscillations also appear abrupt (sub-year) based on the more recent time period (Figs.…”

What Determines the Wavelength of Self-Organized Shoreline Sand Waves?

“…Some of them are linked to surfzone rhythmic bars (megacusps) but we will here focus on those that are not necessarily linked to surfzone bars and that in general occur at larger length and time scales, i.e., km's and yr's. These shoreline sand waves are episodically or persistently found along many sandy coasts (Bruun 1954, Verhagen, 1989, Inman et al 1992, Thevenot and Kraus 1995, Gravens 1999, Guillén et al 1999, Stive et al 2002, Ruessink and Jeuken 2002, Davidson-Arnott and van Heyningen 2003, Medellín et al 2008, Alves 2009, Vila-Concejo et al 2009, Falqués et al 2011a, Kaergaard et al 2011, Ryabchuk et al 2011. They can be triggered by different physical mechanisms, including forcing by offshore bathymetric anomalies or input of large quantities of sand at inlets and rivers, but they can also emerge from irregularities of an otherwise rectilinear coast in absence of any forcing at their length scale.…”

Modeling shoreline sand waves on the coasts of Namibia and Angola

“…The undulations do not only occur in the shoreline position but the bathymetric contours also undulate with decreasing amplitude up to a certain depth. Shoreline sand waves are episodically or persistently found along various sandy coasts around the world (Bruun, 1954, Verhagen, 1989Inman et al, 1992;Thevenot and Kraus, 1995;Gravens, 1999;Guillén et al, 1999;Stive et al, 2002;Ruessink and Jeuken, 2002;Davidson-Arnott and van Heyningen, 2003; Medellin et al, 2008; Alves, 2009).…”

“…Shoreline sand waves can be triggered by different physical mechanisms, including forcing by offshore bathymetric anomalies (Gravens, 1999) or periodic input of large quantities of sand due to inlets and rivers (Thevenot and Kraus, 1995). However, sand waves can also emerge from small irregularities of an otherwise rectilinear coast in absence of any forcing at its wavelength.…”

“…The undulations do not only occur in the shoreline position but the bathymetric contours also undulate with decreasing amplitude up to a certain depth. Shoreline sand waves are episodically or persistently found along various sandy coasts around the world (Bruun, 1954, Verhagen, 1989Inman et al, 1992;Thevenot and Kraus, 1995;Gravens, 1999;Guillén et al, 1999;Stive et al, 2002;Ruessink and Jeuken, 2002;Davidson-Arnott and van Heyningen, 2003; Medellin et al, 2008; Alves, 2009).Shoreline sand waves can be triggered by different physical mechanisms, including forcing by offshore bathymetric anomalies (Gravens, 1999) or periodic input of large quantities of sand due to inlets and rivers (Thevenot and Kraus, 1995). However, sand waves can also emerge from small irregularities of an otherwise rectilinear coast in absence of any forcing at its wavelength.…”