Evaluation of Effect of Recycle Use of Sand at Northern End of Sand Spit on Shimizu Coast

Abstract

At the northern end of the Shimizu coast, a steep slope and submarine canyon develop and approximately 6×10⁴ m³/yr of sand has been discharged into the deep sea through the steep slope every year, resulting in the net loss of sand. To prevent sand from discharging into the offshore zone, the recycle use of sand at the north end of the coast was considered. The effect of sand excavation near the shoreline at the north end of the coast was investigated using the contour-line-change model. It was found that minimum volume of excavation was 2×10⁴ m³/yr for the erosion not to expand to the surrounding coast under the condition that longshore sand transport is 6×10⁴ m³/yr.