Abstract
Sand dunes and other natural coastal barriers (e.g. barrier islands) represent important components of the defense system against consequences of storm surges. However, in many coastal systems, major storm surges represent important drivers of coastal erosion. Increased extreme events potentially result in accelerated coastal erosion, coastal barrier breaching, and coastal flooding. The response of a barrier to a storm surge is often determined by mutual interaction among the driving hydrodynamics, the subsequent morphodynamics, and the local geology, including spatial variations of subaqueous bathymetry and subaerial topography. However, the effect of alongshore variability of soil properties on the alongshore varying response is not yet considered. Therefore, this study examines soil parameters that may affect coastal erosion during major storm surges. Moreover, it applies a novel extension of the numerical model XBeach that accounts for spatial variation of soil properties to an artificial dune system of spatially varying soil permeability. Results showed that variability of soil permeability alongshore the dune results in alongshore varying resistance to erosion so that breaches may occur at the locations of less resistance that are corresponding to locations of higher soil permeability. Outcomes of the numerical simulations proved also that reduced soil permeability represents a nature-based solution that increases the resilience of natural defense systems during major storm surges by mitigating rates of coastal erosion.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/1ERwbW5BmYA
Highlights
Recent extreme storm surges induced for instance by (i) hurricanes Irma that hit Florida in 2017 (Xian et al 2018) and Katrina affecting Louisiana in 2005 (Fritz et al 2007), (ii) the 2010 storm Xynthia that impacted south-western Europe (Bertin et al 2012), and (iii) the 2013/2014 winter storms that impacted the UK coastline (Masselink et al 2016) have proven that coastal areas are highly vulnerable environments to coastal floods
It is a real challenge that arises from the fact that the breaching process represents a mutual interaction between (i) the hydraulic loading, (ii) the alongshore complexities of barriers topography and fronting bathymetry and (iii) the type and properties of the barrier’s soil, which may vary along the barrier
This study addressed the alongshore variability of coastal erosion, of natural coastal barriers under storm surges
Summary
Recent extreme storm surges induced for instance by (i) hurricanes Irma that hit Florida in 2017 (Xian et al 2018) and Katrina affecting Louisiana in 2005 (Fritz et al 2007), (ii) the 2010 storm Xynthia that impacted south-western Europe (Bertin et al 2012), and (iii) the 2013/2014 winter storms that impacted the UK coastline (Masselink et al 2016) have proven that coastal areas are highly vulnerable environments to coastal floods. When Run 2 is re-considered with decreased porosity value (i.e. n0 = 0.3 instead of 0.4), the erosion is decreased as shown in Figure 9 because of increasing the resistance and the modified critical Shields number according to the dilatancy theory (Equation 5).
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