2020 Volume 76 Issue 2 Pages I_330-I_335
In order to clarify the dynamics of sediment transport when water is discharged in the direction perpendicular to the shoreline on the coast where longshore sediment transport is dominant, field experiments of sediment movement using colored sand tracer were carried out on the water discharge at the Hamaoka Nuclear Power Station. The experiments were conducted for three months in the winter season when eastward coastal currents were dominant. 6.6 t of blue colored sand was injected into the water outlet of the power plant, and the appearance of colored sand was observed in the sea area in front of the water outlet and the neighboring coast. As a result, the colored sand in the offshore area was found at a depth of less than 7 m, which implies a high probability that sand movement by the discharge water does not reach the closure depth for sediment movement (hc = 10 m) in this area. Moreover, the colored sand on the beach was found on the east and west ends of the survey area (about 12 km in the coastal direction); thus, it has become clear that sand movement by a longshore current is widespread quickly.
