Storm Surge Hazard in Canada

Storm surges occur frequently in Canada mainlydue to extra-tropical cyclones (ETC'S) also referred to as winter storms. The hurricanes from the Gulf of Mexico can affect eastern Canada including Lakes Ontario and Erie regions, after they get modified and acquire some extra-tropical characteristics. Storm surges have occurred both on the Atlantic and Pacific coasts, in the Gulf of St.Lawrence, St.Lawrence Estuary, Bay of Fundy, Hudson Bay, James Bay, Northwest Passage, Beaufort Sea, the Great Lakes and other large lakes such as Lake Winnipeg.Squall lines which are embedded in the largerscale synoptic systems like the ETC'S could also generate storm surges (referred to as edge waves) in Lakes Huron, Erie and Ontario (edge waves are most prominent in Lake Michigan, but Canada has no territory touching this lake). The effect of climate change on storm surges in the Canadian water bodies could be two-fold. First, there may be some possible intensification of the weather systems and the associated wind fields resulting in bigger surges. Second, and probably even more relevant, is an east-west and north-south shift in the tracks of the weather systems, which could expose certain new areas to storm surge activity.A high priority for proper assessment of storm surge hazard is the production of maps showing inundation zones for storm surges that might occur in populated coastal areas. Such maps can be used to improve public awareness of tsunamis and for planning purposes (i.e., to reduce or avoid the risk).     

Changes in North Sea storm surge conditions for four transient future climate realizations

Storm surges in the North Sea are one of the threats for coastal infrastructure and human safety. Under an anthropogenic climate change, the threat of extreme storm surges may be enlarged due to changes in the wind climate. Possible future storm surge climates based on transient simulations (1961–2100) are investigated with a hydrodynamical model for the North Sea. The climate change scenarios are based on regionalized meteorological conditions with the regional climate model CCLM which is forced by AR4 climate simulations with the general circulation model ECHAM5/MPIOM under two IPCC emission scenarios (SRES A1B and B1) and two initial conditions. Possible sea level rise in the North Sea is not taken into account. The analysis of future wind-induced changes of the water levels is focused on extreme values. Special emphasis is given to the southeastern North Sea (German Bight). Comparing the 30-year averages of the annual 99 percentiles of the wind-induced water levels between the four climate realizations and the respective control climates, a small tendency toward an increase is inferred for all climate change realizations toward the end of the twenty-first century. Concerning the German Bight, the climate change signals are higher for the North Frisian coastal areas than for the East Frisian ones. This is consistent with an increase in frequency of strong westerly winds. Considering the whole time series (1961–2100) for selected areas, this tendency is superimposed with strong decadal fluctuations. It is found that uncertainties are related not only to the used models and emission scenarios but also to the initial conditions pointing to the internal natural variability.     

Maximum Storm Surge Curve Due to Global Warming for the European North Sea Region During the 20th–21st Century

Computations of storm surges during the 20th century needs to incorporate globalwarming of about 0.6 °C ± 0.2 °C (IPCC, 2001). In order totake this global warming into consideration, the development of all storm surgesoccurred during the 20th century have been analysed. The study comprises determiningto what degree the storm surge curve and storm surge level depend on each other. Thisfact can be used to calculate a maximum storm surge curve and each single storm surgeevent can be summarised. The tendency of the surge and wind parameters do not showthat this maximum storm surge levels in the 20th century will occur earlier than predicted, however, the global warming of 0.6 °C will extend the duration of the mean storm surge curve.     

A numerical study of storm surges caused by cold-air outbreaks in the Bohai Sea

Storm surges in the Bohai Sea are not only associated with tropical cyclones and extra-tropical cyclones, but also cold-air outbreaks. Cold-air outbreaks attack China from four major tracks, with each track having its own prevailing wind over the Bohai Sea. As the pressure field of cold-air outbreaks can be converted into the surface wind, storm surges can be investigated by the pressure field of cold-air outbreaks entirely. This paper took the different major tracks, pressure field, and high wind period into consideration and constructed 20 scenarios to describe the actual situation of cold-air outbreaks. Based on the results modeled by FVCOM, the influence of various cold-air outbreaks on the maximum surge in the Bohai Sea and the probability of the surge elevation at three typical tide gauges were investigated. Finally, a powerful decision-making tool to estimate storm surges induced by cold-air outbreaks was provided.     

Mitigation of Flooding and Cyclone Hazard in Orissa, India

Storm surges generated by the strong tangential wind stressesand normal atmospheric pressure gradients at the sea surface due to tropical cyclones (TC'S)have been studied with the goal of detecting any significant and systematic changes due to climatechange. Cyclone and storm surge data for the 19th and 20th centuries for the Bay of Bengalcoast of the state of Orissa in India are available to varying degrees of quality and detail,the data being more scientific since the advent of the India Meteorological Department in 1875.Based on more precise data for the period 1971 to 2000, statistical projections have been madeon the probable intensities of tropical cyclones for various return periods. The super cyclone ofOctober 29, 1999 (SC1999) appears to have a return period of about 50 years. The cyclones of1831, 1885 and possibly the one in 1895 could have been super cyclones. During the 19th century,there were 72 flooding events associated with cyclones, whereas in the 20th century therewere only 56 events. There was no observational evidence to suggest that there was an increaseeither in the frequency or intensity of cyclones or storm surges on the coast of Orissa. However,the impact of cyclones and surges is on the increase due to increase of population and coastalinfrastructure.     

渤海湾西部风暴潮漫滩数值模拟

基于ROMS海洋模式,结合近年的地质实测资料,建立了渤海湾西部地区风暴潮漫滩的数值模型。对模型进行验证后,对渤海湾西部区域重现期为50a、100a、200a及500a的风暴潮漫滩进行了数值模拟,分析了不同重现期风暴潮漫滩发展的动态过程及最大漫滩淹水范围。结果表明,数值模型基本能反映风暴潮的增水趋势,能够模拟风暴潮漫滩发生发展的动态过程。随着风暴潮强度的增加,渤海湾西部地区淹水范围具有从东海岸向西部内陆区域扩展的趋势。通过曲线拟合发现,风暴潮最大漫滩面积比值与高水位之间基本呈线性关系。     

Simulation of water levels and extent of coastal inundation due to a cyclonic storm along the east coast of India

The devastation due to storm surge flooding caused by extreme wind waves generated by the cyclones is a severe apprehension along the coastal regions of India. In order to coexist with nature’s destructive forces in any vulnerable coastal areas, numerical ocean models are considered today as an essential tool to predict the sea level rise and associated inland extent of flooding that could be generated by a cyclonic storm crossing any coastal stretch. For this purpose, the advanced 2D depth-integrated (ADCIRC-2DDI) circulation model based on finite-element formulation is configured for the simulation of surges and water levels along the east coast of India. The model is integrated using wind stress forcing, representative of 1989, 1996, and 2000 cyclones, which crossed different parts of the east coast of India. Using the long-term inventory of cyclone database, synthesized tracks are deduced for vulnerable coastal districts of Tamil Nadu. Return periods are also computed for the intensity and frequency of cyclones for each coastal district. Considering the importance of Kalpakkam region, extreme water levels are computed based on a 50-year return period data, for the generation of storm surges, induced water levels, and extent of inland inundation. Based on experimental evidence, it is advocated that this region could be inundated/affected by a storm with a threshold pressure drop of 66 hpa. Also it is noticed that the horizontal extent of inland inundation ranges between 1 and 1.5 km associated with the peak surge. Another severe cyclonic storm in Tamil Nadu (November 2000 cyclone), which made landfall approximately 20 km south of Cuddalore, has been chosen to simulate surges and water levels. Two severe cyclonic storms that hit Andhra coast during 1989 and 1996, which made landfall near Kavali and Kakinada, respectively, are also considered and computed run-up heights and associated water levels. The simulations exhibit a good agreement with available observations from the different sources on storm surges and associated inundation caused by these respective storms. It is believed that this study would help the coastal authorities to develop a short- and long-term disaster management, mitigation plan, and emergency response in the event of storm surge flooding.     

Risk assessment on storm surges in the coastal area of Guangdong Province

The coastal area of Guangdong Province is one of the most developed regions in China. It is also often under severe risk of storm surges, as one of the few regions in China which are seriously threatened by storm surges. Based on the data of storm surges in the study area in the past 30 years, the return periods of 18 tide stations for storm surge are calculated separately. Using the spatial analysis technology of ArcGIS, combined with the topography data of the study area, the submerged scope for storm surge in the coastal area of Guangdong Province is determined, and the hazard assessment is carried out. According to the view of systematic point, this article quotes the result of vulnerability assessment which was done by the author in the previous research. Based on the hazard evaluation and vulnerability evaluation, risk assessment of storm surges in the study region is done, and the risk zoning map is drawn. According to the assessment, Zhuhai, Panyu and Taishan are classified as the highest risk to storm surges in Guangdong Province; Yangdong, Yangjiang and Haifeng are in higher risk to storm surges; Dongguan, Jiangmen, Baoan and Huidong are in middle risk to storm surges; Zhongshan, Enping, Shanwei, Huiyang, Longgang and Shenzhen are in lower risk of storm surges; Guangzhou, Shunde and Kaiping are in the lowest risk to storm surges. This study builds a complete process for risk assessment of storm surges. It reveals the risk of storm surges in the coastal cities, and it would guide the land use of coastal cities in the future and provide scientific advices to the government for the prevention and mitigation of storm surge disaster. It has important theoretical and practical significance.     

Storm surge modelling for the Bay of Bengal and Arabian Sea

Most of the countries around the North Indian Ocean are threatened by storm surges associated with severe tropical cyclones. The destruction due to the storm surge flooding is a serious concern along the coastal regions of India, Bangladesh, Myanmar, Pakistan, Sri Lanka, and Oman. Storm surges cause heavy loss of lives and property damage to the coastal structures and losses of agriculture which lead to annual economic losses in these countries. About 300,000 lives were lost in one of the most severe cyclones that hit Bangladesh (then East Pakistan) in November 1970. The Andhra Cyclone devastated part of the eastern coast of India, killing about 10,000 persons in November 1977. More recently, the Chittagong cyclone of April 1991 killed 140,000 people in Bangladesh, and the Orissa coast of India was struck by a severe cyclonic storm in October 1999, killing more than 15,000 people besides enormous loss to the property in the region. These and most of the world’s greatest natural disasters associated with the tropical cyclones have been directly attributed to storm surges. The main objective of this article is to highlight the recent developments in storm surge prediction in the Bay of Bengal and the Arabian Sea.     

A modeling study of coastal inundation induced by storm surge,sea-level rise,and subsidence in the Gulf of Mexico

The northern coasts of the Gulf of Mexico (GoM) are highly vulnerable to the direct threats of climate change, such as hurricane-induced storm surge, and such risks are exacerbated by land subsidence and global sea-level rise. This paper presents an application of a coastal storm surge model to study the coastal inundation process induced by tide and storm surge, and its response to the effects of land subsidence and sea-level rise in the northern Gulf coast. The unstructured-grid finite-volume coastal ocean model was used to simulate tides and hurricane-induced storm surges in the GoM. Simulated distributions of co-amplitude and co-phase lines for semi-diurnal and diurnal tides are in good agreement with previous modeling studies. The storm surges induced by four historical hurricanes (Rita, Katrina, Ivan, and Dolly) were simulated and compared to observed water levels at National Oceanic and Atmospheric Administration tide stations. Effects of coastal subsidence and future global sea-level rise on coastal inundation in the Louisiana coast were evaluated using a “change of inundation depth” parameter through sensitivity simulations that were based on a projected future subsidence scenario and 1-m global sea-level rise by the end of the century. Model results suggested that hurricane-induced storm surge height and coastal inundation could be exacerbated by future global sea-level rise and subsidence, and that responses of storm surge and coastal inundation to the effects of sea-level rise and subsidence are highly nonlinear and vary on temporal and spatial scales.     

Impact of wind gusts on sea surface height in storm surge modelling, application to the North Sea

Storm surge models usually do not take into account the explicit effect of wind gusts on the sea surface height. However, as the wind speed enters quadratically into the shallow water equations, short-term fluctuations around the mean value do not average out. We investigate the impact of explicitly added gustiness on storm surge forecasts in the North Sea, using the WAQUA/DCSM model. The sensitivity of the model results to gustiness is tested with Monte Carlo simulations, and these are used to derive a parametrisation of the effect of gustiness on characteristics of storm surges. With the parametrisation and input from the ECMWF model archive, we run hindcasts for a few individual cases and also the 2007–2008 winter storm season. Although the explicit inclusion of gustiness increases the surge levels, it does not help to explain, and hence reduce, the errors in the model results. Moreover, the errors made by ignoring gustiness are small compared to other errors. We conclude that, at present, there is no need to include gustiness explicitly in storm surge calculations for the North Sea.     

Hydrodynamic Response of Northeastern Gulf of Mexico to Hurricanes

The northeastern Gulf of Mexico in the USA is extremely susceptible to the impacts of tropical cyclones because of its unique geometric and topographic features. Focusing on Hurricanes Ivan (2004) and Katrina (2005), this paper has addressed four scientific questions on this area’s response to hurricanes: (1) How does the shallow, abandoned Mississippi delta contribute to the storm surge? (2) What was the controlling factor that caused the record-high storm surge of Hurricane Katrina? (3) Why are the responses of an estuary to Hurricanes Ivan and Katrina so different from the corresponding surges on the open coast? (4) How would the storm surge differ if Hurricane Katrina had taken a different course? Guided by field observations of winds, waves, water levels, and currents, two state-of-the-art numerical models for storm surges and wind waves have been coupled to hindcast the relevant hydrodynamic conditions, including storm surges, surface waves, and depth-averaged currents. Fairly good agreement between the modeled and measured surge hydrographs was found. The quantitative numerical simulations and simple qualitative analysis have revealed that the record-high storm surge of Hurricane Katrina was caused by the interaction of the surge with the extremely shallow, ancient deltaic lobe of Mississippi River. A hypothetical scenario formed by shifting the path of Hurricane Katrina to the observed path of Hurricane Frederic (1979) resulted in a much smaller surge than that observed in coastal Mississippi and Louisiana. However, this scenario did still result in a high surge near the head of Mobile Bay. One of the important lessons learned from Hurricane Katrina is that the Saffir–Simpson scale should be systematically revised to reflect the topographic and geometric features of a complex, heterogeneous coast, including the possible surge amplification in an estuary or a submerged river delta.     

Modeling the impact of land reclamation on storm surges in Bohai Sea,China

A nested model for the simulation of tides and storm surges in the Bohai Sea, China, has been developed based on the three-dimensional finite-volume coastal ocean model. The larger domain covers the entire Yellow Sea and Bohai Sea with a horizontal resolution of ~10 km, and the smaller domain focuses on the Bohai Sea with a fine resolution up to ~300 m. For the four representative storm surges caused by extratropical storms and typhoons, the simulated surge heights are in good agreement with observations at coastal tide gauges. A series of sensitivity experiments are carried out to assess the influence of coastline change due to land reclamation in recent decades on water levels during storm surges. Simulation results suggest that changes in coastline cause changes in the amplitude and phase of the tidal elevation, and fluctuations of surge height after the peak stage of the storm surges. Hence, for the assessment of the influence of coastline changes on the total water level during storm surges, the amplitudes and phases of both the tidal and surge heights need to be taken into account. For the three major ports in the Bohai Bay, model results suggest that land reclamation has created a coastline structure that favors increasing the maximum water level by 0.1–0.2 m. Considering that during the storm surges the total water level is close to or even exceeds the warning level for these ports, further increasing the maximum water level by 0.1–0.2 m has the potential to cause severe damages and losses in these ports.

     

A review of cyclone track shifts over the Great Lakes of North America: implications for storm surges

Natural Hazards - Cyclone tracks over the Great Lakes of North America shift, both East–West as well as North–South. The reasons for the shifts are various small-scale as well as...     

Flood Hazard Assessment for a Hyper-Tidal Estuary as a Function of Tide-Surge-Morphology Interaction

Astronomical high tides and meteorological storm surges present a combined flood hazard to communities and infrastructure. There is a need to incorporate the impact of tide-surge interaction and the spatial and temporal variability of the combined flood hazard in flood risk assessments, especially in hyper-tidal estuaries where the consequences of tide and storm surge concurrence can be catastrophic. Delft3D-FLOW is used to assess up-estuary variability in extreme water levels for a range of historical events of different severity within the Severn Estuary, southwest England as an example. The influence of the following on flood hazard is investigated: (i) event severity, (ii) timing of the peak of a storm surge relative to tidal high water and (iii) the temporal distribution of the storm surge component (here in termed the surge skewness). Results show when modelling a local area event severity is most important control on flood hazard. Tide-surge concurrence increases flood hazard throughout the estuary. Positive surge skewness can result in a greater variability of extreme water levels and residual surge component, the effects of which are magnified up-estuary by estuarine geometry to exacerbate flood hazard. The concepts and methodology shown here can be applied to other estuaries worldwide.     

Modelling a storm surge under future climate scenarios: case study of extratropical cyclone Gudrun (2005)

Weather Research and Forecasting atmosphere model and Finite Volume Community Ocean Model were for the first time used under the pseudo-climate simulation approach, to study the parameters of an extreme storm in the Baltic Sea area. We reconstructed the met-ocean conditions during the historical storm Gudrun (which caused a record-high +275 cm surge in Pärnu Bay on 9 January 2005) and simulated the future equivalent of Gudrun by modifying the background conditions using monthly mean value differences in sea surface temperature (SST), atmospheric air temperature and relative humidity from MIROC5 in accordance with the IPCC scenarios RCP4.5 and RCP8.5 for 2050 and 2100. The simulated storm route and storm surge parameters were in good accordance with the observed ones. Despite expecting the continuation of recently observed intensification of cyclonic activity in winter months, our numerical simulations showed that intensity of the strongest storms and storm surges in the Baltic Sea might not increase by the end of twenty-first century. Unlike tropical cyclones, which derive their energy from the increasing SST, the extratropical cyclones (ETCs) harvest their primary energy from the thermal differences on the sides of the polar front, which may decrease if the Arctic warms up. For climatological generalizations on future ETCs, however, it is necessary to re-calculate a larger number of storms, including those with different tracks and in different thermal conditions.     

Storm surges in the northern part of the Sea of Japan

All the available historic records of sea level and appropriate weather charts have been used to study storm surges in the northern part of the Sea of Japan. The generation of surges in this area was investigated by means of a two-dimensional numerical model. Computed sea levels were compared with hourly observed residual sea levels in De-Kastri. The agreement between computed and observed storm surges is quite satisfactory. The relative importance of various meteorological parameters and bottom topography in formation of the strong storm surge on 20–21 September 1975 was studied numerically.     

Numerical simulation and prediction of storm surges and water levels in Shanghai harbour and its vicinity

A water level model incorporating the nonlinear interactions between tides and storm surges for numerical simulation and prediction use is developed in this paper. Using a conventional two-dimensional nonlinear storm surge model and tide model and associated semi-momentum finite-difference scheme, both the storm surges caused by the tropical cyclones hitting Shanghai and the tides in related regions during the period 1949–1990, are numerically simulated. In simulating storm surges, 16 tropical cyclones with different kinds of tracks are chosen. Meanwhile, to simulate tides, the governing equations for tides, along with 63 prescribed tidal constituents at open sea boundaries are numerically computed. Sixteen associated cases of total water-level simulations comprising joint effects linking surges and tides and one case of real-time prediction have been carried out in 1990 on the basis of computed surges and tides. The total water levels thus obtained in this way give better results than those obtained by the traditional method, i.e. without taking into account, in the model, nonlinear coupling between storm surges and tides.Comparison of the predictions of storm surges and the total water level with the hindcast ones in 1990 showed that a relatively larger error of prediction mainly results from the incorrect forecasting of tropical cyclones but not from the prediction method itself.     

Impact of cyclonic wind field on interaction of surge–wave computations using finite-element and finite-difference models

Both finite-element and finite-difference numerical models are applied to simulate storm surges and associated currents generated by tropical cyclones that struck the coast of Andhra Pradesh, located on the east coast of India. During a cyclone, the total water level at any location on the coast is made up of the storm surge, surge–wind wave interaction and the tide. The advanced circulation two-dimensional depth-integrated (ADCIRC-2DDI) model based on finite-element formulation and the two-dimensional finite-difference model of storm surges developed at IIT Delhi, hereafter referred as IITD storm surge model, are used. These models are driven by astronomical tides at the open ocean boundary and cyclonic asymmetric winds over the surface of the computational domain. Comparison of model simulated sea-surface elevations with coarse and finer spatial resolutions suggests that the grid resolution near the coast is very crucial for accurate determination of the surges in addition to the local bathymetry. The model underpredicts surges, and the peak surge location shifts more to the right of the landfall as the spatial resolution of the model becomes coarser. The numerical experiments also demonstrate that the ADCIRC model is robust over the IITD storm surge model for surge computations as the coastline is better represented in the former.     

Correction to: Tropical cyclone: expressions for velocity components and stability parameter

Historically, Leyte Gulf in central eastern Philippines has received catastrophic damage due to storm surges, the most recent of which was during Typhoon Haiyan in 2013. A city-level risk assessment was performed on Leyte Gulf through synthetic storm generation, high-resolution ocean modeling, and decision tree analyses. Cyclones were generated through a combination of a Poisson point process and Monte Carlo simulations. Wind and pressure fields generated from the cyclones were used in a storm surge model of Leyte Gulf developed on Delft3D. The output of these simulations was a synthetic record of extreme sea level events, which were used to estimate maximum surge heights for different return periods and to characterize surge-producing storm characteristics using decision tree analyses. The results showed that the area most prone to surges is the Tacloban–Basey area with a 2.8?±?0.3 m surge occurring at a frequency of every 50 years. Nearby Palo area will likely receive a surge of 1.9?±?0.4 m every 50 years while Giporlos–Salcedo area a surge of 1.0?±?0.1 m. The decision tree analysis performed for each of these areas showed that for surges of 3–4 m, high-velocity winds (>?30 m/s) are consistently the main determining factor. For the areas, Tacloban, Basey, and Giporlos–Salcedo, wind speed was also the main determining factor for surge?>?4 m.