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Situated in the Western Pacific Ocean, Taiwan is frequently affected by powerful typhoons. The present research evaluates the storm surges that could take place along the western coastline of Taiwan, and the design water level that will likely be required by coastal structures in the course of the 21st century to protect coastal settlements. To do so, the intensity of a given case study typhoon (Soudelor, which caused great damage to Taiwan in 2015) that could affect the target case study area (Yunlin county) was modified by taking into account climate change and sea level rise (SLR), by changing the sea surface temperature (SST), atmospheric air temperature (AAT), and relative humidity (RH) in an ensemble of 14 GCMs in CMIP5 according to RCP4.5 and RCP8.5, targeting the year 2041~2060 and 2081~2100 time horizons. The Advanced Research Weather Research and Forecasting Model (WRF-ARW) and the Unstructured Finite Volume Community Ocean Model (FVCOM) were utilized to simulate the typhoons and storm surges. The hindcasting of the historical typhoon showed good agreement with the observed data provided by the Central Weather Bureau (CWB) in Taiwan, and the simulations under future climate change scenarios forecasted an increase in typhoon intensity, especially the maximum wind speed. However, the storm surge simulations indicated a limited increase in storm surge height, and even a decrease when considering also SLR. Nevertheless, the estimated maximum water level, including both effect of SLR and future storm surge height, can increase up to 3.53 m and 3.84 m relative to mean sea level at the tidal stations in Yunlin and Chiayi County, respectively. The results showed that storm surges in the study area, characterized by a shallow bathymetry with many sandbars and land reclamation projects, are highly influenced by the change in water depth due to SLR and tidal changes, and the existence of the Central Mountain Range, which can greatly affect the accuracy of the simulated typhoon wind fields., Journal of Coastal and Hydraulic Structures, Vol. 2 (2022)

An evacuation simulation is a helpful tool to evaluate the effectiveness of various countermeasures. To showcase its effectiveness and importance, the present study applied the authors’ agent-based tsunami evacuation simulation model to investigate the effectiveness of tsunami countermeasures (i.e., early evacuation, restricting car usage, and combination of these two measures) in an area that was affected by the 2011 Tohoku Earthquake and Tsunami (namely that of Tagajyo, Japan). As a result, it was found that restricting residents’ car usage would be a more effective countermeasure compared with simply encouraging people to immediately start evacuation after feeling the earthquake, which was found to be somewhat ineffective. However, if early evacuation were combined with restricted car use, the risk of residents being hit by a devastating tsunami would be significantly lower. The scenario results, therefore, highlighted the importance of tsunami evacuation simulations in formulating effective evacuation and reconstruction plans for coastal communities. Given the estimated return periods of a devastating tsunami, it is natural to assume that the tsunami-affected areas will gradually change; therefore, to ensure continued community resilience, it is imperative that simulation results be updated according to changes made in the urban landscape of the target city. Keywords: agent-based approach; tsunamis; evacuation; coastal resilience; reconstruction plan.

Sea level rise is likely to increase the risks of inundation due to coastal hazards in the course of the 21st century. To understand how different sea level rise (SLR) scenarios will affect the disaster risk management of tsunamis in Japan, the authors applied the Probabilistic Tsunami Hazard Assessment (PTHA), using a logic tree approach, to the eastern coastline of Japan. Considering a similar generation zone as the 2011 Tohoku Earthquake and Tsunami, a number of tsunami propagation simulations were conducted. In the logic tree construction, different branches of magnitude ranges, positions of asperity, recurrence intervals, standard deviations of log-normal distribution and truncations of log-normal distribution were set. The results indicate that the maximum water levels at output points increased according to the different SLR scenarios that were considered. It was also found that the effects that SLR has on expected tsunami heights and 90% confidence intervals are nonlinear and could vary according to location. Such results highlighted the importance of considering the effects of SLR to improve emergency response capacity.

Situated in the Western Pacific Ocean, Taiwan is frequently affected by powerful typhoons. The present research evaluates the storm surges that could take place along the western coastline of Taiwan, and the design water level that will likely be required by coastal structures in the course of the 21st century to protect coastal settlements. To do so, the intensity of a given case study typhoon (Soudelor, which caused great damage to Taiwan in 2015) that could affect the target case study area (Yunlin county) was modified by taking into account climate change and sea level rise (SLR), by changing the sea surface temperature (SST), atmospheric air temperature (AAT), and relative humidity (RH) in an ensemble of 14 GCMs in CMIP5 according to RCP4.5 and RCP8.5, targeting the year 2041~2060 and 2081~2100 time horizons. The Advanced Research Weather Research and Forecasting Model (WRF-ARW) and the Unstructured Finite Volume Community Ocean Model (FVCOM) were utilized to simulate the typhoons and storm surges. The hindcasting of the historical typhoon showed good agreement with the observed data provided by the Central Weather Bureau (CWB) in Taiwan, and the simulations under future climate change scenarios forecasted an increase in typhoon intensity, especially the maximum wind speed. However, the storm surge simulations indicated a limited increase in storm surge height, and even a decrease when considering also SLR. Nevertheless, the estimated maximum water level, including both effect of SLR and future storm surge height, can increase up to 3.53 m and 3.84 m relative to mean sea level at the tidal stations in Yunlin and Chiayi County, respectively. The results showed that storm surges in the study area, characterized by a shallow bathymetry with many sandbars and land reclamation projects, are highly influenced by the change in water depth due to SLR and tidal changes, and the existence of the Central Mountain Range, which can greatly affect the accuracy of the simulated typhoon wind fields.

The file named "time_histories.xls" includesthe time historiesof water surface elevation recorded at wave gauges for all the cases. The file named "summary.xls" includes the summary of the results used in the manuscript.&nbsp

On the 22nd of December 2018 tsunami waves generated by the flank collapse of the Anak Krakatau volcano in Indonesia flooded the shorelines of the nearby Sumatra and Java islands. The authors conducted a field survey of the Krakatau group of islands to clarify the volume of the collapsed flank and the run-up of the tsunami around the island themselves. To aid with the simulation of this complex tsunami and document the current situation of the islands, bathymetric surveys, aerial drone and panoramic video mapping were also carried out. The results show that while much of the source directionality was towards the SE of Anak Krakatau, significant wave run-ups were also measured towards the NW, indicating that further numerical modelling is needed to fully explain this event., Journal of Coastal and Hydraulic Structures, Vol 1 (2021): Single articles