Improvement of Numerical Simulation Using Applied Statistical Properties of Directional Waves by Typhoons

Kim, D.-H.; Yoo, C.-I.; Jeong, Y.-H.; Lee, S.-Y., and Kim, H.-J., 2021. Improvement of numerical simulation using applied statistical properties of directional waves by typhoons. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 231–235. Coconut Creek (Florida), ISSN 0749-0208. Typhoon-generated wave fields are of importance both scientifically for understanding coastal zone protection and operationally for predicting potentially hazardous conditions for coastal regions. However, the effects of directional wave-to-wave characteristics near bays and estuaries during typhoons are poorly understood due to a strong lack of wave field data. To improve the accuracy of wave height design, this study investigated a highly accurate numerical simulation using the statistical properties of directional waves. Directional wave data were collected using the directional wave recorder MIDAS-DWR, the Geoje and Haeundae floating buoys, and the Gwangan light beacon on typhoons Ma-on and Muifa in July and August, 2011. Moreover, numerical simulation results from STWAVE based on the wave action balance equation were compared with significant wave heights and periods of collected in-situ measurement data. Model input parameters included significant wave height and peak period, as well as wave direction either from wave gauge observations (Case 1) or wave direction statistical properties (Cases 2 and 3). Numerical simulations using the mean and standard deviation of principal wave direction observation data in Mode ± 45° for the largest wave height (Case 3) showed excellent agreement. Results show that wave characteristics can be accurately analyzed using statistical analysis of wave direction rather than actual wave direction inputs, which fluctuates highly in the outer sea. Further, a numerical experiment considering the influence of local wind and flow was performed, showing that the influence of these factors on wave characteristics during typhoons can be studied continuously.