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Soft measures such as evacuation planning are recommended to mitigate the loss of life during tsunamis. Two types of evacuation models are widely used: (i) agent-based modelling (ABM) defines sets of rules that individual agents in a simulation follow during a simulated evacuation; and (ii) geographical information systems (GIS) are more accessible to city planners, but cannot incorporate the dynamic behaviours found in ABMs. The two evacuation modelling methodologies were compared through a case study by assessing the state of evacuation preparedness and investigating potential mitigation options. The two models showed different magnitudes for mortality rates and facility demand but had similar trends. Both models agreed on the best solution to reduce the loss of life for the community. GIS may serve as a useful tool for initial investigation or as a validation tool for ABMs. ABMs are recommended for use when modelling evacuation until GIS methodologies are further developed. Key words: evacuation model, agent-based model, GIS model, tsunami inundation, coastal hazards. Des mesures souples, comme la planification d'evacuation, sont recommandees pour attenuer les pertes de vie lors de tsunamis. Deux types de modeles d'evacuation sont largement utilises : (i) la modelisation fondee sur les agents (MFA) definit des ensembles de regles que les agents individuels d'une simulation suivent pendant une evacuation simulee tandis que (ii) les systemes d'information geographique (SIG) sont plus accessibles aux urbanistes, mais ne peuvent integrer les comportements dynamiques des MFA. Les deux methodes de modelisation d'evacuation ont ete comparees au moyen d'une etude de cas en evaluant l'etat de preparation a l'evacuation et en examinant les options d'attenuation possibles. Les deux modeles presentaient des ampleurs differentes pour les taux de mortalite et la demande d'installations, mais des tendances semblables. Les deux modeles concordaient quant a la meilleure solution pour reduire les pertes de vie dans la collectivite. Les SIG peuvent servir d'outil pour l'enquete preliminaire ou comme outil de validation pour les MFA. Il est recommande d'utiliser les MFA lors de la modelisation d'evacuation jusqu'a ce que les methodologies de SIG soient developpees davantage. [Traduit par la Redaction] Mots-cles : modele d'evacuation, modele fonde sur les agents, modele de systeme d'information geographique (SIG), inondation par tsunami, dangers cotiers., 1. Introduction 1.1. Evacuation planning as a tsunami mitigation measure In Japan, hard-structural tsunami mitigation measures such as the Kamaishi breakwater and other seawalls protecting the coastal areas experienced partial [...]

On January 1 2024, at 16:10 JST, an earthquake of Mw 7.5 occurred underneath the Noto Peninsula of Ishikawa Prefecture, Japan. This event caused a cascading disaster impact on cities in the Noto Peninsula through a series of strong earthquake shakes, strong ground motions, slope failures, liquefaction, fire, and tsunamis. The tsunami first reached Suzu City a few minutes after the earthquake, eventually affecting approximately 340 km of the coast from the Ishikawa to Niigata Prefectures. The Coastal Engineering Committee of the Japan Society of Civil Engineers conducted an organized post-event field survey to understand the impact of tsunamis on land. This study summarizes the post-event field survey results and provides a general understanding of tsunami behavior and damage using measured tsunami inundation and run-up heights. [ABSTRACT FROM AUTHOR]

Hydraulic experiments using a wave flume with a wind tunnel at a scale of 1/40 were carried out to investigate the effect of wind on wave overtopping of a vertical seawall. To ascertain the possible effects of wave breaking, incident waves with various wave steepness (0.0102 to 0.0371) and three kinds of wind forcing (0 m/s, 6.84 m/s, 10.04 m/s) were used. The authors found that winds significantly increased the overtopping rate in general, and that there is a clear relationship between the overtopping rate and the wave steepness. Velocity fields obtained from PIV analysis revealed that the onshore winds directly enhanced the transport of overtopping water mass. The influence of the wind on the wave hydrodynamic processes that indirectly have an effect on the overtopping rate (such as the formation of a partially standing wave, breaker location, and breaker type) is also discussed. The perspective of treating wave overtopping as a transport of water mass could provide a novel understanding of complex fluid behavior, which would help to formulate countermeasures against future disasters influenced by intensive wind forcing. [ABSTRACT FROM AUTHOR]

The actions of wind and atmospheric pressure associated with tropical cyclones (e.g. typhoons) are considered the primary factors behind the generation of storm surges, though the fields used in meteorological models can sometimes deviate from observations. To improve these, the direct modification method (DMM) has been previously proposed, though this only modifies the wind field of a typhoon, and further development is necessary for applying it to storm surge hindcasts. The present work describes the development of a semi-empirical gradient wind balance-based method (GWB-M) for modifying both the wind and pressure fields in meteorological models, based on the dynamic relationship between the wind and pressure in typhoons (i.e. gradient wind balance). The applicability of GWB-M was assessed through a storm surge hindcast based on Typhoon Faxai in 2019, which generated powerful waves and a storm surge at Tokyo Bay. GWB-M improved the time series of 10 m wind speed and sea level pressure, with their spatial distributions being more realistic than those in DMM and blending parametric typhoon models (BM), which cannot take into account the influence of the complex topography around Tokyo Bay. Further, the maximum sea level anomalies after the typhoon made landfall were also captured by GWB-M with a higher accuracy than DMM. [ABSTRACT FROM AUTHOR]

The roll-on/roll-off (ro-ro) transport system, which plays a huge role in the transportation and economy of the Philippines, mainly uses piers to provide smooth berthing of ships. However, its structural configuration attracts different hazards causing damage, particularly to piles. Tsunamis produce devastating wave forces. This may heavily result in discontinuity of the whole port operation as there will be no available berthing structure for ships. Hence, this study was conducted to determine the structural resilience of the pile-supported piers of the Port of Batangas against tsunami loads at different variations of wave height and water depth. Structural software was used to model the piers and incorporate calculated tsunami drag forces. Furthermore, pushover analysis was performed to produce the base shear versus displacement curves needed for the calculation of the robustness index. The rapidity index, on one hand, is based on an interview with the Philippine Ports Authority - Port Management Office (PPA-PMO) of Batangas resulting in recovery rates for demolition works and pile replacement. Combining these indices using the concept of resilience triangle, values of the resilience index ranging from 0.0 to 1.0 were calculated at both longitudinal and transverse directions. As a result, the piers were categorized as highly resilient in almost 50% of the tsunami load cases. It proved that the pier with existing batter piles exhibits higher resilience than the other which is only supported by vertical piles. [ABSTRACT FROM AUTHOR]

Haiyan in 2013 was one of the most powerful typhoons to have affected the Philippines, devastating in its path a wide portion of Leyte, and causing extensive damage to structures in Tacloban City. To understand the likely impacts that would be exerted by a storm surge on a structure deemed important, the authors used a coupled model that hindcasted the flooding that took place during Haiyan. This coupled model included the use of the Weather Research and Forecasting (WRF) Model (with Bogussing scheme) to simulate the atmospheric conditions during the passage of Haiyan, the Finite Volume Coastal Ocean Model (FVCOM) to simulate the storm surge and obtain the boundary conditions for the wind and flood (hydrostatic, hydrodynamic, and breaking wave), and the Structural Analysis and Designing Program (STAAD.Pro) to calculate the corresponding axial, shear, and bending moment envelopes based on the storm surge simulation. A 4-floor public school building in Tacloban was modeled and the effects that the storm surge would have on a corner column were analyzed. Based on the results, the axial, shear, and moment at the corner column significantly increased when considering flood loads, indicating the importance of including such loads in the design of essential structures. [ABSTRACT FROM AUTHOR]

As part of its economy-wide decarbonization target towards 2050, Japan plans to increase renewable generation, especially offshore wind, for which the country has a high potential. However, this resource is currently under-developed as available turbines are prone to shut-downs and can even suffer damage during the passage of typhoons. With new typhoon proof (T-class) turbines being currently developed by various companies, Japan now aims to develop 10 GW of offshore wind between 2021 and 2030, and 91 GW in the long-term. This research estimates the impact of integrating offshore wind into the Japanese main power grid using T-class turbines by considering three scenarios. First, a business-as-usual (BAU) case with 10 GW offshore wind capacity (following the 6th Strategic Energy Plan of Japan). Second, an offshore wind capacity of 91 GW. Third, the 91 GW offshore capacity being redistributed amongst regions to maximize its integration opportunities (Scenario 2). The simulations were carried out using the Energy System simulation model (EnSym). The results show that the BAU and Scenario 1 resulted in offshore wind achieving 1.7% and 7.28% of generation share, respectively, increasing to 9.77% for Scenario 2. Increasing the share of offshore wind in the energy mix mainly replaced liquefied natural gas (LNG). [ABSTRACT FROM AUTHOR]

Following the devastating Typhoon Haiyan, a project initiated by the Philippine government, known as Road Heightening and Tide Embankment (RHTE), was constructed to protect the coastal communities of the Leyte region in the Philippines against future storm surges. This research focuses on this newly built structure, which was investigated for coastal flooding and wave overtopping against extreme waves. Experimental and numerical modeling were conducted to simulate wave-structure interaction under different water level conditions. A 1∶30 scale representative geometry of the tide embankment was set up inside a wave flume containing a scaled beach profile representing areas beyond the No-Build Zone mandated by the government. Dam-break wave flow was used to generate turbulent bores similar to that of a storm surge. For the numerical model, SolidWorks and ANSYS CFX version 17.1 software were used. The multiphase Volume of Fluid (VOF) method was used to track the free surface of the fluid flow and was shown to be an accurate tool for numerical validation, as the maximum wave height distributions in the presence of the structure using both methods were in close agreement with one another, but the numerical results overestimated the wave heights. The final design of the tide embankment with a return wall was modeled using ANSYS CFX. Experimental and numerical models generated wave heights that were higher than Typhoon Haiyan with inundation heights of 6 to 9 m above mean sea level (MSL) approaching the structure while the inland wave height was approximately 2 to 4 m above MSL. Results of the experiment also showed that the presence of the structure reduced the water level by 1 to 5 cm (about 0.3 to 1.5 m in actual scale). Moreover, the presence of a return wall will reduce the inland inundation height between 0.1 and 0.5 m above MSL. [ABSTRACT FROM AUTHOR]