Data related to "Near-bed sediment transport during offshore bar migration in large-scale experiments"

Abstract: 

This paper presents novel insights into hydrodynamics and sediment fluxes in large-scale laboratory experiments with bi-chromatic wave groups on a relatively steep initial slope (1:15). An Acoustic Concentration and Velocity Profiler provided detailed information of velocity and sand concentration near the bed from shoaling up to the outer breaking zone including suspended sediment and sheet flow transport. The morphological evolution was characterized by offshore migration of the outer breaker bar. Decomposition of the total net transport revealed a balance of onshore-directed, short wave-related and offshore-directed, current-related net transport. The short wave-related transport mainly occurred as bedload over small vertical extents. It was linked to characteristic intrawave sheet flow layer expansions during short wave crests. The current-related transport rate featured lower maximum flux magnitudes but occurred over larger vertical extents. As a result, it was larger than the short wave-related transport rate in all but one cross-shore position, driving the bar's offshore migration. Net flux magnitudes of the infragravity component were comparatively low but played a non-negligible role for total net transport rate in certain cross-shore positions. Net infragravity flux profiles sometimes featured opposing directions over the vertical. The fluxes were linked to a standing infragravity wave pattern and to the correlation of the short wave envelope, controlling suspension, with the infragravity wave velocity.

About the data:

The data on beach profile (from mechanical profiler), velocity (from ACVP and ADV), sand concentration (from ACVP and OBS) and water surface elevation (from RWG, AWG and PT) measurements is given in .mat (MATLAB) files.

The folder “Beach Profiles” contains the measurements from the mechanical profiler before and after each test. To save time, only the morphologically active section of the profiles was measured. Additionally, the folder contains the initial profiles at the start of a sequence (after application of the benchmark waves). Here the full profile was measured.

The structure “MobFrame” contains the absolute cross-shore position of the mobile frame (from which detailed measurements were taken) in the considered tests.

The folder “ACVP” contains structures with ensemble-averaged velocity and concentration measurements in vertical reference to the undisturbed bed level or a few bins below it (zeta0-coordinate system) sampled at 50.5051Hz. For better interpretation of the measurements, it also features the ensemble-averaged intrawave instantaneous erosion depth (bed elevation) and the upper limit of the sheet flow layer.

The folder “ADV” contains structures with the ensemble-averaged ADV data of each test sampled at 100Hz. Apart from the velocity components of each ADV it contains the vertical elevation of each ADV with respect to the ACVP transceiver. The ADV measurements were not subject to the same vertical referencing procedure that was described in the paper for the near-bed ACVP measurements and a more or less constant distance to the bed was assumed.

The folder “OBS” contains structures with the ensemble-averaged OBS data of each test sampled at 40Hz. Apart from the concentration measurements it contains the vertical elevation of the OBSs with respect to the ACVP transceiver.

The folder “ETA” contains structures with the ensemble-averaged water surface elevation measurements in many different absolute cross-shore locations in the flume sampled at 40Hz.

For visualizing the near-bed concentration data, which may not be as trivial as visualizing the rest of the data, an example of MATLAB code is given:

%S=ACVP_xx; %to choose which ACVP file you want to look into
con=S.c;
con(con<1)=1; %to cater for the cells where the logarithm is not defined
xphase=linspace(0,1,length(S.solbed)).*ones(size(S.c,2),size(S.c,1));
figure; hold on; box on; 
[C,h]=contourf(xphase,S.z,log10(transpose(con)),[0:0.1:3]); 
cbh=colorbar; caxis([0 3]); 
set(h,'edgecolor','none'); 
tt=get(cbh,'Title'); set(tt,'String','$^{10}log(c)$ $[kg/m^3]$','Interpreter','Latex');
plot(xphase(1,:),S.solbed,'k','Linewidth',1.5);
plot(xphase(1,:),S.solflo,'r','Linewidth',1.5);
xlabel('$t/T_r$','Interpreter','Latex')
ylabel('$\zeta_0$ $[m]$','Interpreter','Latex')
set(gca,'Fontsize',18)