Many coastal areas in Japan are in a distressed condition due to beach erosion, making beachpreservation and restoration important issues. Sand bypassing systems offer one countermeasure for beach erosion. A typical example of conventional sand bypassing is collecting sand with an excavator and transporting it by dump truck. However, this method requires some mechanism to move the shovel used to collect the sand and considerable manpower, including dump truck drivers.Moreover, truck transportation also causes air pollution, noise, and other environmental problems.
　This paper proposes a new sand bypassing system of simple composition comprised of a suction pipe with holes, on which a slurry pump is mounted. A water jet pipe is attached to the underside of the suction pipe. The pump inlet is connected to the suction pipe, and the outlet is connected to a sand discharge pipe.
　The device is placed on an area where sand has accumulated and water jets out from the water jet pipe, fluidizing the surrounding sand, which is then drawn into the suction pipe together with seawater. As the sand is fluidized, the suction pipe/pump assembly sinks into the sand under its own weight, enabling continuous collection/transportation of sand.
　A prototype experimental device was test-manufactured and used in field experiments. In continuous operation for approximately 1 hour, it was possible to collect/transport 200-500 l/m of sand, which is roughly equivalent to 50,000 m³ in a 3-month period.