Experimental study of bore-driven swash hydrodynamics on impermeable rough slopes: Fid-Bau Portal

Experimental study of bore-driven swash hydrodynamics on impermeable rough slopes

Kikkert, G.A. / O'Donoghue, T. / Pokrajac, D. / Dodd, N.

Abstract A detailed experimental investigation of the hydrodynamics of large-scale, bore-driven swash on impermeable, rough beach slopes is described. The experiments were carried out on 1:10 impermeable, rough slopes with three different surface roughnesses based on 1.3mm sand, 5.4mm gravel and 8.4mm gravel. The large-scale discrete swash event was produced by the collapse of a dambreak-generated bore on the beach. Simultaneous depths and velocities were measured using LIF, Laser-induced fluorescence, and PIV, particle image velocimetry, respectively, yielding better resolution of the hydrodynamics than previous studies. Depth time-series, instantaneous velocity profiles, depth-averaged velocities, instantaneous turbulent kinetic energy profiles, depth-averaged turbulent kinetic energy, Reynolds stress profiles and bed shear stresses are presented for five cross-shore measurement locations in the swash. The measurements resolve the backwash shoreline position, and the late backwash period when depths are shallow and velocities are high. The detailed data can be used to test and develop advanced numerical models for bore-driven waves on rough slopes.

Highlights ►Detailed hydrodynamics of bore-driven swash on impermeable, rough slopes. ►Large-scale laboratory experiments measuring simultaneous depths and velocities. ►Shows effects of slope roughness on bulk flow and turbulence properties. ►Yields measures of time-varying bed shear stress across the swash zone.