Maintaining Tidal Inlet Channels by Fluidization

Along the barrier islands off the east coast of the U.S. and at other areas of the world, there exist many tidal inlet channels which connect the ocean to back bay areas. An innovative technique is tested to maintain a stable, navigable channel. Water is pumped into a perforated pipe buried beneath the sand, and the water flowing through the perforations fluidizes the overlying sand. The fluidized sand along the pipe is then removed either by gravity flow, slurry pump, or entrainment in the overlying ebb tidal current. Laboratory experiments provided information necessary for the design of such a fluidization system, specifically, data on hole orientation, hole size, hole spacing, flow rate necessary for fluidization, and the effect of slurry removal on the channel shape. A small-scale field test, designed from the laboratory data and performed on a beach face, shows that the technique is technically feasible and that the design data is sound. In the field test, full fluidization along fluidization pipe was achieved and the fluidized sand was removed by pumping the slurry or, when the pipe was sloped, by gravity flow.