Storm surge induced by Tropical Storm Pabuk (2019) and its impact by track variation scenarios on the Thailand coast

Tropical Storm Pabuk in 2019, the most severe storm event in the past two decades, provided a unique opportunity to assess storm surge impact in the Gulf of Thailand. Employing the COMCOT-SURGE model with a two-layer nested-grid configuration, this study examined storm surges from offshore to nearshore driven by the ERA5 reanalysis winds and the 1980 Holland wind model. The spatial and temporal variations of storm surges generated by Tropical Storm Pabuk were both investigated. The ERA5-driven case indicated severe storm surges in the coastal regions of Thailand and matched well with the tide-gauge observations in the timing and amplitude of peak surges. However, the Holland wind model case showed the maximum storm surges shifted southward and poorly agreed with the measured surges. This discrepancy was attributed to the absence of environmental winds in the parametric wind model. Moreover, the effect of the radius of maximum winds on storm surges was tested. To further explore potential storm surges in the Gulf of Thailand, this study focused on the variations in storm tracks along the latitudinal axis and associated storm surges. Among the proposed storm track scenarios, the one landing more northward in Thailand than Pabuk represented the most severe case to the Thailand coast, followed by Pabuk’s track. In the proposed scenarios, cities such as Chumphon, Surat Thani, and Nakhon Si Thammarat were found to face higher storm surge risks than other regions.