Generating potential risk maps for typhoon-induced waves along the coast of Taiwan

Typhoon-induced waves threaten the coastal areas of Taiwan each year. The roaring waves caused by typhoon Meranti (2016) even destroyed a lighthouse in a fishing port on the southwestern coast of Taiwan. Therefore, there has been increased interest in creating potential risk maps for typhoon-induced waves along the coast of Taiwan. In this study, the highest intensity and lowest intensity typhoons (HITs and LITs, respectively) for each category from 1977 to 2016 were selected. A fully coupled tide-surge-wave model was utilized to map the distributions of maximum significant wave heights for 18 typhoon events. Each map was classified into one of 5 levels and employed to generate maximum and minimum potential risk maps for typhoon-induced waves. Our results demonstrate that the northern and the eastern coasts of Taiwan are threatened by violent waves (significant wave heights (SWHs) range from 7 to 11.5 m) over a coastline length of 236.4 km and roaring waves (SWHs exceeding 11.5 m) over a coastline length of 298.1 km under HIT conditions. The lengths of coastline threatened by big waves (SWHs ranging from 3 to 6 m) and small waves (SWHs less than 3 m) are 637.7 km and 553.4 km, respectively, under LIT conditions.