Study on Locally Varying Inundation Characteristics Induced by Super Typhoon Haiyan. Part 2: Deformation of Storm Waves on the Beach with Fringing Reef Along the East Coast of Eastern Samar

Abstract

This paper investigates characteristics of coastal damage caused by Super Typhoon Haiyan with special focuses on locally varying wave deformations along the coast of Eastern Samar fronted by shallow fringing reef. The paper first summarized the field survey results and indicated that the erosion depth of the beach had negative correlation with the width of fringing reef along the straight coastline while a drastic variation of the damage levels was observed around Matarinao Bay mouth. A phase-resolved nonlinear dispersive wave model and a linear mild slope equation model were respectively applied for computations of wave deformations on the long-straight coastline with fringing reef and on the coast around Matarinao Bay. Computed rapid decay of waves on the reef reasonably explained observed negative correlations between erosion depth and the reef width. Around Matarinao Bay, on the other hand, wave refraction and diffraction played a significant role to explain wave concentration on the reef just outside of the bay mouth and also significant wave attenuation inside the bay mouth. Observed wave deformation characteristics were not sensitive to incident wave angles and periods and were reasonably consistent with the observed alongshore variation of maximum water levels and corresponding damages along the coast.