Locally Concentrated Damages and Erosions on Seisho Coast Caused by Typhoon T0709

Abstract

This paper explores physical mechanisms of locally concentrated damages and erosions observed on Seisho coast caused by typhoon T0709. Field survey was first conducted to capture alongshore distributions of hydrodynamic forces during the storm. The measured water mark elevations showed certain periodic undulation along the coast and their peak was located at the most damaged area. Time-series of surface water levels and velocities recorded at Hiratsuka Experiment Station were then analyzed and it was found that both free and bounded long waves grew as T0709 approached to the damaged site and short wave heights increased. Numerical analysis is finally carried out to investigate how free long waves and nearshore currents affect observed locally concentrated damages.