Lee, J.H. and Kim, T.R., 2018. Study of High Waves caused by Slanting-fetch Effects along the Coast. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 831–835. Coconut Creek (Florida), ISSN 0749-0208.

Design wave height estimation for the ports and coastal structures are mainly based on the waves from offshore wind which have long fetches enough to develop high waves. The waves generated by short fetched land wind are usually neglected because they are thought to be small and short period waves. However, in case of land wind oblique to the long coast line with short fetch, unexpected long period high waves are developed along the coast by slanting-fetch effects. These high waves can damage human lives as well as coastal structures, but are difficult to predict using offshore wave measurement system. Therefore, it is important to understand the characteristics of waves by slantingfetch and prepare countermeasures against them.

This paper analyzes observed wind and wave data in the East Sea, on Feb. 6–8th and Dec. 12–14th in 2013, when waves were developed by slanting-fetch effects near the coast. During these periods, strong northwest wind of over 15 m/sec lasted more than 24 hours, but southwestward waves with significant wave height of over 1.5 m and peak period of over 10 sec were observed at Hupo Harbor in spite of land wind with short fetch.

Unstructured WAVEWATCH III model is executed to simulate the waves generated by slanting-fetch effects and RDAPS/UM wind data with 12 km resolution provided by NCMS/KMA are used as forcing input data. The numerical wave model results at Hupo Harbor show relatively good agreement with in-situ measurement data explaining high waves with long period by slanting-fetch effects, and both observed and simulated wave directional spectrum at Hupo Harbor show strong energy in long period and southwestward direction.