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\textbf{Experiment description}\newline
Hurricane Sandy made landfall as a Category 1 post-tropical storm on the New Jersey Coast on October 29, 2012. The storm severely impacted the Fire Island barrier island off the Long Island, New York, coast, where profile volume loss along the entire barrier island varied from 25\% to 75\% \citep{hapke2013}. Off the coast of Bellport (NY, \autoref{fig:overview_FI}), an uninhabited section of the barrier island Wilderness Area breached during Sandy. Dune crests were lowered, and large wash-over fans developed in the area around the breach. Prior to the storm, the area was covered by dune grass, wetland- and woody vegetation. The sea floor offshore of Fire Island shows shoreface-connected sand ridges in the western part and smaller, sorted bedforms along the eastern part of the island that includes the Wilderness area \citep{schwab2013}.  The cross-shore profiles are characterized by a steeply sloped beach (1 in 20 slope), a pronounced alongshore-uniform breaker bar, and a foreshore slope that gradually becomes less steep (1 in 85 slope) up to the wide continental shelf at a depth of ~25 m. 

During Sandy, maximum water levels (surge and tide) ranged 1.8 m (Montauk) to 3.5 m NAVD881 (The Battery) along the barrier island and offshore significant wave heights reached 10 m with periods up to 14 s. LiDAR surveys of the island were flown pre-Sandy in May 2012 \citep{fredericks2016} and post-Sandy on November 5, 2012. A median grain size of 400 μm was reported at Wilderness \citep{buster2018} with a grading of D90/D50 = 1.5. 

Comparison of pre- and post-storm observations of bed elevations (Figure 1) shows that the initial dune crest heights were ranging from only 2 to 6 m, much lower than generally found in the Netherlands. The observed cumulative erosion-sedimentation patterns show that the dune front eroded several meters along the entire stretch of coast. A breach developed between kilometer marks (KM) 1 and 1.2 where originally a high dune was located. Large overwash deposits were observed east of the breach (KM 1.2–2). West of the breach the dune crests were initially higher, and impact remained in the collision regime with little overwash deposits.  

\citet{lugt2019} setup a 2DH morphodynamic XBeach model with hydrodynamic forcing extracted from a regional coupled D-Flow FM/SWAN model, and showed that the model predicted erosion volumes, dune-crest lowering and breach-formation well. The model bathymetry and boundary conditions of this 2DH model is used to set-up 1D transects and validate the BOI-XBeach settings for morphological storm impact. 

${tools.image(os.path.join(data_path,'FireIsland'), 'overview_FI.png', 'Left: Model domain extent of the nested regional D-Flow FM/SWAN model (in grey) and the XBeach model (in red): Wilderness breach. Right: observed pre- (top) and post-(middle) bathymetry and sedimentation/erosion (bottom).',label='overview_FI', width=145)}

\textbf{Results}\newline		
The XBeach model results are validated using the post-Sandy LiDAR data obtained on November 5, 2012. The dune erosion volumes and retreat distances at 3 m +NAVD88, based on the measured pre- and post-storm profiles and the XBeach simulations for all 6 profiles are tabulated in \autoref{tab:Fire-Island}. Furthermore, the pre- and post-storm profile for profiles 5, 305 and 405 based on the measurements and on the XBeach simulation are presented in \autoref{fig:FireIsland_005}, \autoref{fig:FireIsland_305} and \autoref{fig:FireIsland_405} respectively.

${tools.table('FireIsland/', 'skill.tex', 'Modeled and measured erosion volumes [$m^3/m$] and retreat distances [m] at 3 m +NAVD88 in absolute values. NaN means that no dune retreat could be determined, i.e. the dune has breached. ', 'Fire-Island')} 

${tools.image('FireIsland/005', 'BL_BeforeAndAfterStorm_Profile005.eps', 'XBeach results for cross-shore transect 005 at Fire Island. Initial bed levels are depicted by the black dotted line, observed post-storm bed levels by the black solid line and XBeach model results are presented in red. The modelled dune erosion is shown by the red shaded area.',label='FireIsland_005', width=145)}

${tools.image('FireIsland/305', 'BL_BeforeAndAfterStorm_Profile305.eps', 'XBeach results for cross-shore transect 305 at Fire Island. Initial bed levels are depicted by the black dotted line, observed post-storm bed levels by the black solid line and XBeach model results are presented in red. The modelled dune erosion is shown by the red shaded area.',label='FireIsland_305', width=145)}

${tools.image('FireIsland/405', 'BL_BeforeAndAfterStorm_Profile405.eps', 'XBeach results for cross-shore transect 405 at Fire Island. Initial bed levels are depicted by the black dotted line, observed post-storm bed levels by the black solid line and XBeach model results are presented in red. The modelled dune erosion is shown by the red shaded area.',label='FireIsland_405', width=145)}



