Spatio-temporal analysis of storm surge in the Korean Peninsula

The Korean Peninsula (KP) located in the Northwest Pacific have different topographic features. West coast of the KP has large tidal variations. If storm surge occurred at high tide, the west coast is vulnerable to flooding. The south coast has a complex coastline with hundreds of islands. Its complex topography can amplify storm surge height (SSH) and it also makes it difficult to conduct numerical modeling for storm surge. Moreover, as the KP is located in the pathways of typhoons, it has been affected by an average of three typhoons every year. The KP has actually suffered from storm surge-induced disaster several times in the past. In order to plan efficient and effective countermeasures against storm surge disasters, it is required to identify the vulnerability of coastal regions in the KP. Therefore, this study quantitatively analyzed the frequency and cause of occurrence of storm surges that occurred along the Korean coast in the past.

First, this study collected observed tidal data at 48 tide stations which are installed along the coast of the KP and performed a hormonic analysis on the observed tidal data to build a database of SSH information that occurred along the coast of the KP from 1979 to 2021. Next, the cause of the storm surge was evaluated based on the occurrence time of the high-level SSH. If the storm surge occurred in winter season, it was treated as being caused by an extra-tropical cyclone, and if in summer season, by and tropical cyclone. Lastly, storm surge vulnerable areas were assessed based on frequency and level of the SSH. To this end, the coast of the KP was divided into five zones: the northwest coast, the southwest coast, Jeju island, the southeast coast and northeast coast. The frequency of the high-level SSH generated in those zones was calculated, and areas where storm surge occurred a lot were selected as vulnerable areas.

As a result of the study, it was found that the high-level SSH with more than 1 m in the KP are caused by tropical cyclone in summer, and the area most vulnerable to storm surge is the southeast coast.

However, the observed tidal data used in this study has a limitation in that the collection period differs depending on the zone: the observation period is longer for the southeast coast than for the southwest coast. Looking at the paths of past typhoons, many typhoons passed through the west coast, so the possibility that the southwest coast would have been judged to be more vulnerable than the southeast coast cannot be ignored if the observed tidal data for the southwest coast were more abundant. In addition, since storm surge is phenomenon that is affected not only by meteorological conditions but also by topographic conditions (e.g., complexity of coastline, water depth, etc.), spatio-temporal analysis of storm surge by topographic conditions is going to be conducted through future research.

 

Acknowledgement

This work was supported by the National Research Foundation of Korea grant funded by the Korea government(MSIT) (No. 2022R1C1C2009205).