DOI: 10.6084/m9.figshare.29149982.v2
title: Data Availability for Barrier Island Response to Energetic Storms: a Global Process-Based Modelling Overview

description: The table contains the morphological and hydrodynamic variables and the erosion and flooding process-based indicators to support the paper "<i>Barrier Island Response to Energetic Storms: </i><i>a Global Process-Based Modelling Overview</i>" by V. Fanti, Ó. Ferreira, V. Kümmerer and C. Loureiro<b>Morphological variables:</b><br>- Latitude and Longitude (°) of the barrier islands selected.<br>- Depth of closure (m): the morphodynamic boundary separating the active upper shoreface from the non-active lower shoreface. It was estimated from the Hallermeier's (1981) formulation from the Hs that is exceeded for 12 hours per year and the associated wave period.- Nearshore slope (-): calculated from the depth of closure to the MSL (h = 0).- Total barrier volume (m3/m): calculated as the volume, per linear meter alongshore, between MSL and the dune crest.- Beach slope (-): calculated between the MSL and the pre-storm dune toe.- Beach width (m): calculated as the horizontal distance between the MSL and the pre-storm dune toe.- Berm volume (m3/m): calculated as the volume, per linear meter alongshore, between MSL and the pre-storm dune toe.- Dune half width (m): calculated as the horizontal distance between the pre-storm dune toe and the pre-storm dune crest. Only the half width was considered due to the presence of different morphologies of the barrier island, with some having vegetation in the back barrier area, others a second dune, others a lagoon.- Dune height (m): calculated as the vertical distance between the pre-storm dune toe and the pre-storm dune crest. Three methods to identify the dune toe location were tested: the second derivative; the farthest point from a linear fit between the position of the mean high water (average of all high tide levels in the record) and the dune crest; setting a threshold slope change. The latter was the method chosen for giving the most reasonable results after visual inspection.- Dune volume (m3/m): calculated as the volume, per linear meter alongshore, between the pre-storm dune toe and the dune crest.- D50 (mm): mean grain size obtained from fitting the Dean equilibrium profile from the MSL to the depth of closure.- Dimensionless fall velocity (-): estimated as in Anthony (1998) from the breaker wave heigh Hb, which was assumed to correspond to the average storm Hs propagated to ~30 m depth with SWAN; the mean storm Tp was also obtained from the SWAN propagation to ~30 m water depth; while the sediment fall velocity ws was estimated according to Soulsby (1997). Assuming that the morphology is in equilibrium with the hydrodynamic forcing, a lower than 1 is associated with a fully reflective beach, 1 &lt; &lt; 6 intermediate and &gt; 6 dissipative.<b>Hydrodynamic variables:</b>- Maximum offshore Hs (m): maximum significant wave height during the synthetic storm, which corresponds to the 50-year return period Hs estimated from the WAVERYS global reanalysis and propagated to ~30 m water depth with SWAN.- Maximum offshore Tp (s): maximum peak period during the synthetic storm estimated from the WAVERYS global reanalysis and propagated to ~30 m water depth with SWAN.- Relative storm direction (-): the SWAN propagated direction is modified so that the XBeach input direction ranges from 180° to 360° (nautical convention, clockwise from the north), with 270° waves approaching perpendicularly to the coast. As wave direction is a circular variable, in order to allow its use in correlation analysis it was linearized with the sine function and referenced to 270°. This results in negative values (until -1) for storms approaching from the north and positive values (until 1) for storms from the south.- Storm power (MWh/m): cumulative storm power that takes into account both the duration and intensity of the event, calculated following Splinter et al. (2014) from the duration of the storm event, is the seawater density (1025 kg/m3), the acceleration due to gravity and the temporal resolution of the wave data.- Wave energy at the depth of closure (Nm/m2): estimated as the sum of the wave energy (E) output parameter from XBeach at the depth of closure over the entire storm duration.- Wave energy at 2 m depth (Nm/m2): estimated as the sum of the wave energy (E) output parameter from XBeach at 2 m water depth over the entire storm duration.- Maximum water level (m): calculated as the sum of the peak of the mean spring tidal cycle and the peak of the storm surge that corresponds to a 50-year return period Hs, both estimated from the GTSM database.- Tide range (m): amplitude of the tidal signal during the storm (excluding the storm surge), calculated as the sum of the highest peak and lowest through.- Mean annual Hs (m): estimated over the 30 years of WAVERYS Hs data.- Mean annual tide range (m): estimated as the mean difference between high and low tide over the 27 years of GTSM tidal data.Process-based indicators The erosion and flooding response variables are also reported, obtained respectively from XBeach surfbeat (XB-SB) and XBeach non-hydrostatic (XB-NH) runs:<b>Erosion process-based indicators:</b><br>- Collision hours (%): following Sallenger's (2000) storm impact scale a collision regime is when the run-up (estimated from the run-up gauge of XB-SB) exceeds the dune toe. The percentage number of hours of collision was calculated over the total storm duration.<br>- Maximum run-up XB-SB (m): estimated using the gauge option from XBeach that moves with the waterline and gives a time-series output of locations representing the run-up at time steps of 100 s.- Dune eroded volume (m3/m): calculated as the initial dune volume minus the final dune volume, integrated from the pre-storm dune toe until the dune crest. Positive (negative) values stand for erosion (accumulation).- Berm eroded volume (m3/m): calculated as the initial berm volume minus the final berm volume, integrated from the MSL until the dune toe. Such simplification was necessary due to the lack of more accurate information on the berm location, which is not captured by the 12 m resolution DEM model TanDEM-X.- Total eroded volume (m3/m): calculated as the initial total volume minus the final total volume, integrated from MSL until the dune crest.- Maximum retreat (m): maximum horizontal retreat calculated from MSL to the dune crest.- Mean retreat (m): mean horizontal dune retreat calculated from MSL to the dune crest.- Dune toe retreat (m): horizontal difference between pre-storm dune toe position and post-storm dune toe position.- Shoreline retreat (m): horizontal difference between pre-storm shoreline position and post-storm shoreline position referenced to MSL.- Relative volume loss (%): percentage of eroded volume over the total pre-storm volume (calculated from MSL to the dune crest).<b>Flooding process-based indicators:</b>- Overwash hours (%): following Sallenger's (2000) storm impact scale the overwash regime is when the run-up (estimated from the run-up gauge of XB-NH) exceeds the dune crest. The total number of hours when the run-up was higher than the dune crest was divided by the total storm duration, and the percentage was computed.- Maximum run-up XB-NH (m): highest elevation referenced to MSL that was reached by the water during the storm determined by identifying the maximum value registered by the run-up gauge at each time step.- Overtopping volume (m3): estimated by computing the total volume of water that overtopped the dune crest. This was done using the overtopping discharge in the x-direction (parameter qx in the XBeach output). Specifically, for each time step, the volume of water that overtopped the dune crest was calculated as the product of the discharge (qx in m2/s) and the time interval between measurements. This was then summed across all time steps to obtain the total overtopping volume in cubic meters (m³).- Average overtopping discharge (l/s/m): the average rate at which water overtops the dune crest in liters per second per meter of barrier length, computed from the total volume of overtopping water over the storm divided by the storm duration and the cross-sectional area of the overtopping basin (estimated from the profile length).- Number of overtopping waves (-): determined by counting the number of events during the storm when the water level exceeded the dune crest.- Mean overtopping event duration (s): calculated by first identifying the start and end times of each overtopping event (using a peak detection algorithm on the run-up data). The duration of each event was computed as the difference between the start and end times, and the average of these durations was then taken to give the mean overtopping event duration in seconds.- Overwash extent (m): most landward point reached by the run-up in the backbarrier measured from the dune crest.