Typhoon Surge Research Articles

An extended, 2.4-ka long record of western Pacific tsunamis and pumice rafts in northern Taiwan: Tsunami recurrence, pumice sources, and drifting routes

Encircled by arcs and trenches, the western Pacific region of the Philippine Sea is exposed to trans-oceanic tsunamis and pumice rafts. However, shortage of extended archive has limited our knowledge of tsunami recurrence, pumice sources, and drifting routes. This study identifies a backshore colluvium with three new pumice gravel layers in northern Taiwan, stratigraphically below four previously reported pumice-bearing paleotsunami deposits from the last millennium. The new layers are attributed to tsunamis, based on foreshore-derived sediments, facies characteristics reflecting suspension-rich turbulent flow process, supratidal locations exceeding typhoon surge heights, and mismatched super typhoon occurrences. The tsunami record therefore extends in duration from 1.0 to 2.4 ka with an increase in event number from four to seven, which unfolds new time intervals, stretches the recurrence from 100–400 to 100–800 years, and indicates complicated tsunami occurrences and sources in this region. Simultaneously, a stranded pumice archive is established by six of the seven paleotsunami deposits with abundant pumices rounded by grain-to-grain abrasion during drifting. The pumices consist of black, shoshonitic trachyte–trachyandesite grains and white, low-K dacite–rhyolite grains, indicating diverse sources and drifting routes. The unique alkali and adjoining subalkaline volcano provinces of the Izu-Bonin-Mariana Arc might have successively generated pumice rafts since 2.4 ka that embarked the Kuroshio counter and branch currents for northern Taiwan in a ∼2000-km-long course across the Philippine Sea. White rhyolite pumice domination is also present and comparable in composition to the southern Ryukyu pumice, indicating a ∼200 km-long northwest-bound route.

Effect of Summer Sea Level Rise on Storm Surge Analysis

Typhoons occur intensively between July and October, and the sea level is the highest during this time. In particular, the mean sea level in summer in Korea is higher than the annual mean sea level about 14.5cm in the west coast, 9.0 to 14.5cm in the south coast, and about 9.0 cm in the east coast. When the rising the sea level and a large typhoon overlap in summer, it can cause surges and flooding in low-lying coastal areas. Therefore, accurate calculation of the surge height is essential when designing coastal structures and assessing stability in order to reduce coastal hazards on the lowlands. In this study, the typhoon surge heights considering the summer mean sea level rise (SH_m) was calculated, and the validity of the analysis of abnormal phenomena was reviewed by comparing it with the existing surge height considering the annual mean sea level (SH_a). As a result of the re-analyzed study of typhoon surge heights for BOLAVEN (SANBA), which influenced in August and September during the summer sea level rise periods, yielded the differences of surge heights (cm) between SH_a and SH_m 7.8~24.5 (23.6~34.5) for the directly affected zone of south-west (south-east) coasts, while for the indirect south-east (south-west) coasts showed -1.0~0.0 (8.3~12.2), respectively. Whilst the differences between SH_a and SH_m of typhoons CHABA (KONG-REY) occurred in October showed remarkably lessened values as 5.2~ 14.2 (19.8~21.6) for the directly affected south-east coasts and 3.2~6.3 (-3.2~3.7) for the indirectly influenced west coast, respectively. The results show the SH_a does not take into account the increased summer mean sea level, so it is evaluated that it is overestimated compared to the surge height that occurs during an actual typhoon. Therefore, it is judged that it is necessary to re-discuss the feasibility of the surge height standard design based on the existing annual mean sea level, along with the accurate establishment of the concept of surge height.

Environmental influences on sinking rates and distributions of transparent exopolymer particles after a typhoon surge at the Western Pacific

A multidisciplinary approach was used to investigate the causes of the distributions and sinking rates of transparent exopolymer particles (TEPs) during the period of September–October (2017) in the Western Pacific Ocean (WPO); the study period was closely dated to a northwest typhoon surge. The present study discussed the impact of biogeophysical features on TEPs and their sinking rates (sTEP) at depths of 0–150 m. During the study, the concentration of TEPs was found to be higher in areas adjacent to the Kuroshio current and in the bottom water layer of the Mindanao upwelling zone due to the widespread distribution of cyanobacteria, i.e., Trichodesmium hildebrandti and T. theibauti. The positive significant regressions of TEP concentrations with Chl-a contents in eddy-driven areas (R2 = 0.73, especially at 100 m (R2 = 0.75)) support this hypothesis. However, low TEP concentrations and TEPs were observed at mixed layer depths (MLDs) in the upwelling zone (Mindanao). Conversely, high TEP concentrations and high sTEP were found at the bottom of the downwelling zone (Halmahera). The geophysical directions of eddies may have caused these conditions. In demonstrating these relations, the average interpretation showed the negative linearity of TEP concentrations with TEPs (R2 = 0.41 ~ 0.65) at such eddies. Additionally, regression curves (R2 = 0.78) indicated that atmospheric pressure played a key role in the changes in TEPs throughout the study area. Diatoms and cyanobacteria also curved the TEPs significantly (R2 = 0.5, P < 0.05) at the surface of the WPO. This study also revealed that TEP concentration contributes less to the average particulate organic carbon in this oligotrophic WPO.

Co-occurrence probability of typhoon surges affecting multiple estuaries in the northern coastal region of Taiwan

Taiwan lies on the northwest Pacific and is usually invaded by typhoons in summers and autumns. When typhoons strike the coast, surges usually occur. In addition, if a typhoon surge occurs during a high-tide period, the water level starts to rise. As a result, largely urbanized and highly populated regions around the estuaries may be devastated by catastrophic damage owing to floodwater elevation rising and unable to drain off floodwater. Therefore, in order to allocate regional resources reasonably and prevent and reduce coastal disasters effectively, it is necessary to estimate the co-occurrence probability of typhoon surges in multiple estuaries. In this study, total 36 typhoon processes are applied to calculate the simultaneous-occurrence probability of typhoon surges in three estuaries in Nan-Kan River, Huang River, and Lan-Yang River in the northern part of Taiwan. We first use certain extreme-value distribution models to fit the simulated peak values of a typhoon surge. These univariate statistical distributions include the Pearson type III, Weibull, generalized extreme value, and lognormal distributions. Through hypothesis and goodness-of-fit tests, the Pearson type III distribution is chosen as the optimal curve to fit the typhoon surges in these three estuaries. Then, according to the dependence of the typhoon surges in these three estuaries, a three-dimensional compound probability distribution model P-GH-TriP3 is constructed, and the joint return periods are calculated. The results indicate the simultaneous-occurrence probability of disasters in these three estuaries is small, which can provide some reasonable proposal for coastal typhoon disaster prevention and reduction and ocean engineering design.

Damage Analysis of Typhoon Surge Flood in Coastal Urban Areas Using GIS and ADCIRC

Choi, H.; Lee, H.J., and Kim, G., 2019. Damage analysis of typhoon surge flood in coastal urban areas using GIS and ADCIRC. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 381-385. Coconut Creek (Florida), ISSN 0749-0208.Typhoon Maemi, which landed in the coastal area of Masan City on September 12, 2003, was the largest coastal disaster in Korea. Typhoon surges can cause extreme flood damage when they overlap with high tides. In this study, the maximum flooding zone according to the highest tide was calculated and the accuracy of the flooding model was analyzed by comparing it with the actual flooding zone in the Masan Bay area. A GIS-based hydrologic model for flood forecasting can complement the disadvantages of complex multidimensional flood damage estimation in which data acquisition and processing are complicated. It is important to establish a method to minimize damage by developing a more accurate damage simulation model. It is necessary to utilize data such as high-resolution satellite images and LiDAR for accurate analysis data considering the topographical characteristics of typhoon surge flood areas in the future.

Assessing the Potential Highest Storm Tide Hazard in Taiwan Based on 40-Year Historical Typhoon Surge Hindcasting

Typhoon-induced storm surges are catastrophic disasters in coastal areas worldwide, although typhoon surges are not extremely high in Taiwan. However, the rising water level around an estuary could be a block that obstructs the flow of water away from the estuary and indirectly forms an overflow in the middle or lower reaches of a river if the occurrence of the highest storm surge (HSS) coincides with the highest astronomical tide (HAT). Therefore, assessing the highest storm tide (HST, a combination of the HSS and HAT) hazard level along the coast of Taiwan is particularly important to an early warning of riverine inundation. This study hindcasted the storm surges of 122 historical typhoon events from 1979 to 2018 using a high-resolution, unstructured-grid, surge-wave fully coupled model and a hybrid typhoon wind model. The long-term recording measurements at 28 tide-measuring stations around Taiwan were used to analyze the HAT characteristics. The hindcasted HSSs of each typhoon category (the Central Weather Bureau of Taiwan classified typhoon events into nine categories according to the typhoon’s track) were extracted and superposed on the HATs to produce the individual potential HST hazard maps. Each map was classified into six hazard levels (I to VI). Finally, a comprehensive potential HST hazard map was created based on the superposition of the HSSs from 122 typhoon events and HATs.

Geological records of South China Sea tsunamis on Penghu Islands, Taiwan

The coasts around the South China Sea are highly populated and threatened by the ubiquitous tsunamigenic structures of the Manila trench-arc system. However, owing to limited historical records and rare geological findings of tsunamis, our comprehension of and preparation for regional tsunami risks are far from sufficient. Located in the NE South China Sea, the Penghu Islands in Taiwan’s western offshore area are selected for a geological tsunami survey because of their advantages of lengthy coastlines and abundant upper Holocene deposits.Three gravel layers of marine incursion events were identified and correlated between three far-separated coastal sections based on the constraints of radiocarbon dating. Intercalated with talus, soil, and dune sand, the gravel layers are poorly sorted, matrix-supported, up to boulder in size, and dominated by marine bioclastics and rounded basalts, which are identical to modern beach gravels. The deposits are located 3–4 m above present sea level, which is significantly higher than the local high tide levels and maximal typhoon surges of 2–3 m high. Furthermore, the deposits are distributed extensively on south-facing shores, indicating relatively large and abnormal inundation events from the South China Sea.Based on the radiocarbon dating results of the event deposits, three tsunamis likely occurred in the periods from the 4th to 6th, 11th to 12th, and 15th to 16th centuries. A recurrence interval of 400–500 years is accordingly associated with these event deposits. These findings demonstrate great tsunami risks exist in the South China Sea basin and call for more attestations and future studies. The major contribution of this study is also supported by the AD 1076 Guangzhou tsunami, which is comparable in age to the middle event deposit.

Copula-Based Joint Probability Analysis of Compound Floods from Rainstorm and Typhoon Surge: A Case Study of Jiangsu Coastal Areas, China

Coastal areas are vulnerable to floods caused by rainstorms and typhoons. It is necessary to ascertain the risk of floods caused by both of these extreme weather events. A conceptual risk model is proposed to evaluate the rainstorm risk, typhoon surge risk, and the compound risk in the coastal areas of Jiangsu Province during the period of 1960–2012. The results of the model show that the typhoon surge risk in the study region is greater than the rainstorm risk. Three Archimedean copulas were used to fit the joint probability distributions of the compound events. The Frank copula and the Gumbel copula proved to be the best-fitting joint distribution function for the Huaibei plain district and the Lixiahe district, respectively. The probability of the extreme compound events not happening is less than 90% in the study region. This means that the flood risk is mainly subject to the encounter of a low-level rainstorm and a low-level typhoon surge. The study shows that the northern region of Jiangsu Province is more vulnerable to the compound risk, and that we should pay more attention to the floods caused by the compound events of rainstorm and typhoon surge.

Estimation of Probable Maximum Sea Level at Macro-tidal Area

The concept of probable maximum sea level was applied to estimate design tide level of which could be applied to a very restricted design requirement such as a nuclear power plant. Furthermore, regarding macro-tidal area such as West Coast, empirical simulation technique was applied as sea level needs to be estimated with considering both tide and typhoon surge. The return period has been set up for 10,000 years, and the sea level was simulated by generating hypothetical typhoon in order to typhoon-surge event which is included in training set. If one year among advanced generation of high tide data for 20 years, is selected, maximum sea level would be set by combination of single typhoon-surge event of the training set in certain time frame. Sea level of 10,000 year return period and others would be estimated by this hypothetical generation. In addition, in order to reflect future climate change, enlargement in storm intensity which could be led more than 20% stronger and increase in sea level regarding RCP 8.5 scenario on the basis of 2100. The probable maximum sea level was ultimately estimated by calculating the maximum extent of confidence intervals in order to maximize the sea level.

A Unified Numerical Model for Typhoon Surge in the Northwestern Pacific

ABSTRACT Kang, S.K.; Seung, Y.H.; Kim, K.O.; Kim, E.J., and Jung, K.T., 2017. A unified numerical model for typhoon surge in the Northwestern Pacific. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 139–143. Coconut Creek (Florida), ISSN 0749-0208. A new finite difference modeling system with modified fetched variable grid technique has been developed in order to predict the typhoon induced surge over the Northwestern Pacific. The grid resolution ranges from 18.5 km (10 ′) in open ocean to 109 m (1/17 ′) near the coastal areas of interest, which is quite suitable for resolving the complicated coastal boundaries of the Korean coasts. The total grid number is about 1,350,000 points and the model computation can be effectively carried out with efficient time interval satisfying 1–30 Courant numbers. This system has various advantages over regular finite difference grid system, allowin...

Bias Correction in Typhoon and Storm Surge Projection Considering Characteristics of Global Climate Model MRI-AGCM3.2S

The typhoons that so often rage across Japan’s southwestern island, Kyushu, are expected to occur even oftener in the future due to global warming. Storm surge projections have been reported based on the super-high-resolution global climate model MRI-AGCM3.2S developed by Japan’s Meteorological Research Institute (MRI). AGCM3.2S overestimates typhoon strength around Japanese islands, however, and this could lead to exaggerated storm surge projection. We therefore evaluate a bias correction method of typhoon strength considering the typhoon characteristics of AGCM3.2 in estimating maximum storm surge anomaly on the Ariake Sea coast. Our results indicated the possibility of storm surge anomaly of 2.8 m, exceeding the current design storm surge anomaly of 2.36 m at the innermost Ariake Sea.

Selection of Methods for Predicting Tidal Levels with a Typhoon Surge Effect

ABSTRACT Yuan, H.; Tan, M., and Wang, W., 2015. Selection of methods for predicting tidal levels with a typhoon surge effect. Accurate prediction of tidal level with strong meteorological effects is very important for human activities in oceanic and coastal areas. Under severe weather, such as typhoons, the contribution of non-astronomical components to tidal level may be as significant as that of astronomical components. The traditional harmonic analysis method and other models based on the analysis of astronomical components do not work well in these situations. The objective of this paper is to select an effective method for predicting the tidal level under the influence of typhoons at Luchaogang, China. The linear regression, back-propagation (BP) and radial basis function neural network methods are compared. Based on the typhoon data and tidal-level data gathered from Pudong Hydrological Bureau, seven parameters of typhoon are extracted and employed as input parameters while the corresponding tidal-l...

A storm surge intensity classification based on extreme water level and concomitant wave height

Storm surge is one of the predominant natural threats to coastal communities. Qingdao is located on the southern coast of the Shandong Peninsula in China. The storm surge disaster in Qingdao depends on various influencing factors such as the intensity, duration, and route of the passing typhoon, and thus a comprehensive understanding of natural coastal hazards is essential. In order to make up the defects of merely using the warning water level, this paper presents two statistical distribution models (Poisson Bi-variable Gumbel Logistic Distribution and Poisson Bi-variable Log-normal Distribution) to classify the intensity of storm surge. We emphasize the joint return period of typhoon-induced water levels and wave heights measured in the coastal area of Qingdao since 1949. The present study establishes a new criterion to classify the intensity grade of catastrophic storms using the typhoon surge estimated by the two models. A case study demonstrates that the new criterion is well defined in terms of probability concept, is easy to implement, and fits well the calculation of storm surge intensity. The procedures with the proposed statistical models would be useful for the disaster mitigation in other coastal areas influenced by typhoons.

Wave-tide-surge coupled simulation for typhoon Maemi

The main task of this study focuses on studying the effect of wave-current interaction on currents, storm surge and wind wave as well as effects of current induced wave refraction and current on waves by using numerical models which consider the bottom boundary layer and sea surface roughness parameter for shallow and smooth bed area around Korean Peninsula. The coupled system (unstructured-mesh SWAN wave and ADCIRC) run on the same unstructured mesh. This identical and homogeneous mesh allows the physics of wave-circulation interactions to be correctly resolved in both models. The unstructured mesh can be applied to a large domain allowing all energy from deep to shallow waters to be seamlessly followed. There is no nesting or overlapping of structured wave meshes, and no interpolation is required. In response to typhoon Maemi (2003), all model components were validated independently, and shown to provide a faithful representation of the system’s response to this storm. The waves and storm surge were allowed to develop on the continental shelf and interact with the complex nearshore environment. The resulting modeling system can be used extensively for prediction of the typhoon surge. The result show that it is important to incorporate the wave-current interaction effect into coastal area in the wave-tide-surge coupled model. At the same time, it should consider effects of depth-induced wave breaking, wind field, currents and sea surface elevation in prediction of waves. Specially, we found that: (1) wave radiation stress enhanced the current and surge elevation otherwise wave enhanced nonlinear bottom boundary layer decreased that, (2) wind wave was significantly controlled by sea surface roughness thus we cautiously took the experimental expression. The resulting modeling system can be used for hindcasting (prediction) the wave-tide-surge coupled environments at complex coastline, shallow water and fine sediment area like areas around Korean Peninsula.

Predict typhoon-induced storm surge deviation in a principal component back-propagation neural network model

To reduce typhoon-caused damages, numerical and empirical methods are often used to forecast typhoon storm surge. However, typhoon surge is a complex nonlinear process that is difficult to forecast accurately. We applied a principal component back-propagation neural network (PCBPNN) to predict the deviation in typhoon storm surge, in which data of the typhoon, upstream flood, and historical case studies were involved. With principal component analysis, 15 input factors were reduced to five principal components, and the application of the model was improved. Observation data from Huangpu Park in Shanghai, China were used to test the feasibility of the model. The results indicate that the model is capable of predicting a 12-hour warning before a typhoon surge.

부산 연안지형 VRS-GPS 계측을 통한 태풍해일 침수예측

A coastal flood area was predicted using the empirical superposition of the typhoon surge level and typhoon wave height along the Busan coastal area. The historical typhoon damages were reviewed, and the coastal topography was measured using VRS-GPS. A FEMA formula was applied to estimate the coastal flood area in a typhoon case when the measured and predicted data of typhoon waves are not available. The results in the area of Haeundae beach and Gwangalli beach were verified using the flood area data from the case of Typhoon Maemi (2003). If a Hurricane Katrina class typhoon were to pass through the Maemi trajectory, the areathat would be flooded along theBusan coastal area was predicted and compared with the results of the Maemi case. Because of the lack of ocean environment data such as data for the sea level, waves, bathymetry, wind, pressure, etc., it is hard to improve the prediction accuracy for the coastal flood area in the typhoon case, which could be reflected in the policy to mitigate a typhoon`s impact. This paper discusses the kinds of ocean environment information that is needed to predict a typhoon`s impact with better accuracy.

PREDICTION OF STORM SURGE INTENSITY IN COASTAL DISASTER EVALUATION

In coastal area, serious storm surge disasters are frequently caused by the higher tidal level and concomitant huge wave heights toward shoreline. Qingdao is located at the southern tip of Shandong Peninsula of China. The storm surge disaster in Qingdao depends on various influencing factors such as the intensity, duration, and route of the passing typhoon. In order to make up the defects of the warning water level, a Poisson Bi-variable Gumbel Logistic Distribution is presented to predict storm surge intensity. On the basis of observed records of tidal level and simultaneously occurred wave height series that are sampled from typhoon processes in Qingdao coastal area of China since 1949, the return periods of typhoon surge are estimated by this model. Then a new criterion is put forward to classify intensity grade of disaster-induced typhoon surges. A practical case indicates that the new criterion is clear in probability concept, easy to operate, and fits the calculation of typhoon surge intensity. Thus the procedure with the proposed statistical model will be a reference for the disaster mitigation in the other coastal area influenced by typhoons.

Variation Characteristics of Typhoon Surge in the Future of Three Major Bay Calculated by Using Result of Climate Projection Model

We simulated typhoon surge around Osaka, Ise and Tokyo bays of typhoons for 10,000 years in each present and future climate. Their typhoons were reproduced by Yasuda(2010) using with a stochastic typhoon model. Yasuda projected typhoons in the future derived by super-high-resolution atmospheric models. In the beginning, we showed that the calculated surge of present climate stochastic typhoons comprised the other of recorded typhoon. Variations of each three bays which were located west to east projected totally similar but different in detail. Near the modal classes their frequencies was decreased, but over the more higher classes their frequencies were increased.

Numerical simulation of typhoon surges along the coast of Taiwan

A numerical model has been designed to study the storm surge induced by typhoon along the coast of Taiwan. The governing equations have been expressed in spherical coordinate system, and a finite difference method has been used to solve them. In the system of hydrodynamical equations, the nonlinear advection and lateral eddy viscosity terms are prominent in shallow coastal waters. Air pressure gradient and wind stresses are the driving forces in the model of typhoon surge. The model has been verified with storm surges induced by Typhoons Herb in 1996, and by typhoons Kai-Tak and Bilis in 2000.

Support vector regression methodology for storm surge predictions

To avoid property loss and reduce risk caused by typhoon surges, accurate prediction of surge deviation is an important task. Many conventional numerical methods and experimental methods for typhoon surge forecasting have been investigated, but it is still a complex ocean engineering problem. In this paper, support vector regression (SVR), an emerging artificial intelligence tool in forecasting storm surges is applied. The original data of Longdong station at Taiwan ‘invaded directly by the Aere typhoon’ are considered to verify the present model. Comparisons with the numerical methods and neural network indicate that storm surges and surge deviations can be efficiently predicted using SVR.