| Summary: | Theory is reviewed which relates infiltration into a permeable beach with the net onshore
or offshore transport of sediment by wave action. This theory is tested experimentally by
using sands of different permeability and by using underdrains in the beach and a pump to
increase the infiltration capacity. Previous studies are reviewed, although these earlier
studies have had different purposes. Some prior investigations have studied wave
propagation over a permeable slope or have determined wave damping and energy
dissipation due to percolation into a porous bed. Other studies have investigated wave
interactions with permeable structures such as rubblemound breakwaters and have shown
that the exchange of fluid between the external and internal flow regions markedly affects
wave uprush, backrush and set-up in the surf zone. A limited number of previous studies
have considered the flow of fluid into a permeable beach and its role in beach
stabilization and erosion control. The present tests were performed in the wave flume of
the Hydraulics Laboratory of the Department of Civil Engineering at the University of
British Columbia. Intermediate and equilibrium beach profiles are presented and
compared. The findings of this study indicate substantial differences between
impermeable and porous material. Experimental results show more permeable beaches
form steeper profiles, while less permeable beaches form shallower profiles. Moreover,
increasing infiltration by pumping initiates immediate onshore sediment motion and
considerable steepening of the cross-sectional profile. To a large extent this steepening
process was reversible when pumping was stopped. The results of this study confirm the
predictions of the theory that infiltration contributes directly to a net onshore stress and
onshore sediment transport. === Applied Science, Faculty of === Civil Engineering, Department of === Graduate
|
|---|
