COMPARISON OF OFFSHORE AND LONGSHORE SAND TRANSPORT AROUND TIP OF MIHONO-MATSUBARA SAND SPIT

Abstract

 At Mihono-matsubara sand spit located at the north end of the Shimizu coast, beach has been eroded due to the imbalance in longshore sand transport and a large amount of sediment discharges offshore through steep seabed. In this study, the changes in cross-sectional areas of the eroded and accreted areas near the tip of the sand spit were calculated on the basis of the bathymetric survey data and the rate of offshore and longshore sand transport on a steep coast was evaluated and compared each other. The offshore discharge of the sediment was estimated to be 6×10⁴ m³/yr between 1998 and 2010, and it increased up to 7.5×10⁴ m³/yr. Furthermore, it was found that 8.7×10⁴ m³/yr of sediment has discharged in the entire area of the sand spit.