Research

11 pages, 8598 KiB

Open AccessArticle

Empirical Fragility Assessment of Three-Waters and Railway Infrastructure Damaged by the 2015 Illapel Tsunami, Chile

by Jessica Rodwell, James H. Williams and Ryan Paulik

J. Mar. Sci. Eng. 2023, 11(10), 1991; https://doi.org/10.3390/jmse11101991 - 16 Oct 2023

Viewed by 912

Despite the importance of critical infrastructure for the effective functioning of communities, their vulnerability to tsunamis remains unstudied. This study addresses this issue by developing empirical fragility curves for infrastructure components currently absent from tsunami vulnerability research. This research applies post-event damage data [...] Read more.

Despite the importance of critical infrastructure for the effective functioning of communities, their vulnerability to tsunamis remains unstudied. This study addresses this issue by developing empirical fragility curves for infrastructure components currently absent from tsunami vulnerability research. This research applies post-event damage data from the 2015 Illapel tsunami in a cumulative link model (CLM) to form fragility curves for three-waters (manholes, culverts, and drain inlets) and railway infrastructure components. The synthesized fragility curves reveal that in response to the flow depth, culverts exhibit the highest vulnerability of all the infrastructures studied. The curves also suggest that culverts, drain inlets, and railways have higher vulnerability when compared to infrastructure such as roads or utility poles. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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14 pages, 3317 KiB

Open AccessArticle

Spatial Transferability of Residential Building Damage Models between Coastal and Fluvial Flood Hazard Contexts

by Ryan Paulik, Shaun Williams and Benjamin Popovich

J. Mar. Sci. Eng. 2023, 11(10), 1960; https://doi.org/10.3390/jmse11101960 - 11 Oct 2023

Viewed by 755

Abstract

This study investigates residential building damage model transferability between coastal and fluvial flood hazard contexts. Despite the frequency of damaging coastal flood events, empirical damage models from fluvial flooding are often applied in quantitative coastal flood risk assessments. This assumes that building damage [...] Read more.

This study investigates residential building damage model transferability between coastal and fluvial flood hazard contexts. Despite the frequency of damaging coastal flood events, empirical damage models from fluvial flooding are often applied in quantitative coastal flood risk assessments. This assumes that building damage response is similar from the exposure to different flood sources. Here, we use empirical data from coastal, riverine and riverine-levee breach flooding events to analyse residential building damage. Damage is analysed by applying univariable and multivariable learning models to determine the importance of explanatory variables for relative damage prediction. We observed that the larger explanatory variable range considered in multivariable models led to higher predictive accuracy than univariable models in all flood contexts. Transfer analysis using multivariable models showed that models trained on event-specific damage data had higher predictive accuracy than models learned on all damage data or on data from other events and locations. This finding highlights the need for damage models to replicate local damage factors for reliable application across different flood hazard contexts. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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20 pages, 18019 KiB

Open AccessArticle

Predicting Compound Coastal Flooding in Embayment-Backed Urban Catchments: Seawall and Storm Drain Implications

by Boxiang Tang and T. W. Gallien

J. Mar. Sci. Eng. 2023, 11(7), 1454; https://doi.org/10.3390/jmse11071454 - 21 Jul 2023

Cited by 2 | Viewed by 1229

Abstract

Urban coastal flooding is a global humanitarian and socioeconomic hazard. Rising sea levels will increase the likelihood of hydrologic events interacting with high marine water levels. These compound events may, in turn, nonlinearly interact with urban infrastructure, potentially resulting in more extreme coastal [...] Read more.

Urban coastal flooding is a global humanitarian and socioeconomic hazard. Rising sea levels will increase the likelihood of hydrologic events interacting with high marine water levels. These compound events may, in turn, nonlinearly interact with urban infrastructure, potentially resulting in more extreme coastal flooding events. Here, an integrated Delft3D-FM based numerical modeling framework is used to concomitantly resolve multi-source flood processes (i.e., high marine water levels, precipitation) and infrastructure (e.g., seawalls, storm drains). Hydrodynamic model results are validated with embayment pressure sensor data and photographic observations from historical events. The impact of tide and precipitation phasing are examined. Multiple storm drain characterizations are presented and evaluated. Results show seawall and storm drain infrastructure is fundamental to accurately resolving spatial and temporal flood dynamics. Importantly, coastal management strategies such as raising seawall elevations to mitigate tidal flooding may exacerbate precipitation-based flooding in low-lying urban regions. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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13 pages, 7684 KiB

Open AccessArticle

Assessing Indirect Impacts of Extreme Sea Level Flooding on Critical Infrastructure

by Charles Lan, Alec Wild, Ryan Paulik, Liam Wotherspoon and Conrad Zorn

J. Mar. Sci. Eng. 2023, 11(7), 1420; https://doi.org/10.3390/jmse11071420 - 15 Jul 2023

Cited by 2 | Viewed by 1309

Abstract

This study investigates the direct and indirect impacts of extreme sea level (ESL) flooding on critical infrastructure. While methods to quantify the direct impacts of ESL flooding on coastal areas are well established, the indirect impacts that extend beyond the directly affected population [...] Read more.

This study investigates the direct and indirect impacts of extreme sea level (ESL) flooding on critical infrastructure. While methods to quantify the direct impacts of ESL flooding on coastal areas are well established, the indirect impacts that extend beyond the directly affected population are less well understood. This study assesses the vulnerability of electricity, road, telecommunication, water supply, and wastewater infrastructure to service disruption from coastal flooding in South Dunedin, New Zealand. We quantified the population affected by single and multiple service losses caused by 100-year average recurrence interval (ARI) ESL flooding across 0.1 m sea-level rise (SLR) increments up to 1.5 m. The study identified an ESL “tipping-point” at 0.6 m SLR, where direct loss of road access and electricity services is extensive, and causes indirect loss of telecommunication services. This also impacted the functionality of a key wastewater pumpstation servicing the wider region. As sea levels in the area are projected to rise 0.60 m in the next ~60–90 years, this information can inform assessments of potential adaptation investments in long-term infrastructure management plans in the face of uncertainty. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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19 pages, 9281 KiB

Open AccessArticle

Coastal Flood at Gâvres (Brittany, France): A Simulated Dataset to Support Risk Management and Metamodels Development

by Déborah Idier, Jérémy Rohmer, Rodrigo Pedreros, Sylvestre Le Roy, José Betancourt, François Bachoc and Sophie Lecacheux

J. Mar. Sci. Eng. 2023, 11(7), 1314; https://doi.org/10.3390/jmse11071314 - 28 Jun 2023

Viewed by 871

Abstract

Given recent scientific advances, coastal flooding events can be modelled even in complex environments. However, such models are computationally expensive, preventing their use for forecasting. At the same time, metamodelling techniques have been explored for coastal hydrodynamics, showing promising results. Developing such techniques [...] Read more.

Given recent scientific advances, coastal flooding events can be modelled even in complex environments. However, such models are computationally expensive, preventing their use for forecasting. At the same time, metamodelling techniques have been explored for coastal hydrodynamics, showing promising results. Developing such techniques for predicting coastal flood information (e.g., inland water depths) requires large enough learning datasets providing such inland information. However, detailed inland coastal flood observations are scarce and—when available—only correspond to a limited number of events. This paper aims at demonstrating how we can fill this gap by introducing a publicly available dataset, presenting its setup, and providing examples of use and recommendations. It has been built for the site of Gâvres (France), relying on the joint use of spectral wave (WW3) and non-hydrostatic wave-flow (SWASH) models, accounting for wave overtopping. It compiles 250 scenarios (defined by time-varying forcing conditions; including real and stochastically generated events) and the resulting maximal flooded areas and water depths (on 64,618 inland points). Its construction required the equivalent of 2 years of simulations on 48 cores. The examples of use of the dataset focus on method developments (metamodelling, forecast), local knowledge, and risk management. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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24 pages, 15499 KiB

Open AccessArticle

Quantifying Mechanisms Responsible for Extreme Coastal Water Levels and Flooding during Severe Tropical Cyclone Harold in Tonga, Southwest Pacific

by Moleni Tu’uholoaki, Antonio Espejo, Moritz Wandres, Awnesh Singh, Herve Damlamian and Zulfikar Begg

J. Mar. Sci. Eng. 2023, 11(6), 1217; https://doi.org/10.3390/jmse11061217 - 13 Jun 2023

Cited by 1 | Viewed by 2169

Abstract

The South Pacific region is characterised by steep shelves and fringing coral reef islands. The lack of wide continental shelves that can dissipate waves makes Pacific Island countries vulnerable to large waves that can enhance extreme total water levels triggered by tropical cyclones [...] Read more.

The South Pacific region is characterised by steep shelves and fringing coral reef islands. The lack of wide continental shelves that can dissipate waves makes Pacific Island countries vulnerable to large waves that can enhance extreme total water levels triggered by tropical cyclones (TCs). In this study, hindcasts of the waves and storm surge induced by severe TC Harold in 2020 on Tongatapu, Tonga’s capital island, were examined using the state-of-the-art hydrodynamic and wave models ADCIRC and SWAN. The contributions of winds, atmospheric pressure, waves, and wave-radiation-stress-induced setup to extreme total water levels were analysed by running the models separately and two-way coupled. The atmospheric pressure deficit contributed uniformly to the total water levels (~25%), while the wind surge was prominent over the shallow shelf (more than 75%). Wave setup became significant at locations with narrow fringing reefs on the western side (more than 75%). Tides were dominant on the leeward coasts of the island (50–75%). Storm surge obtained from the coupled run without tide was comparable with the observation. The wave contribution to extreme total water levels and inundation was analysed using XBEACH in non-hydrostatic mode. The model (XBEACH) was able to reproduce coastal inundation when compared to the observed satellite imagery after the event on a particular coastal segment severely impacted by coastal flooding induced by TC Harold. The coupled ADCIRC+SWAN underestimated total water levels nearshore on the reef flat and consequently inundation extent as infragravity waves and swash motion are not resolved by these models. The suite of models (ADCIRC+SWAN+XBEACH) used in this study can be used to support the Tonga Meteorological Service Tropical Cyclone Early Warning System. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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15 pages, 12322 KiB

Open AccessArticle

Sea-Level Rise Effects on Changing Hazard Exposure to Far-Field Tsunamis in a Volcanic Pacific Island

by Rebecca Welsh, Shaun Williams, Cyprien Bosserelle, Ryan Paulik, Josephina Chan Ting, Alec Wild and Lameko Talia

J. Mar. Sci. Eng. 2023, 11(5), 945; https://doi.org/10.3390/jmse11050945 - 28 Apr 2023

Viewed by 1694

Abstract

Coastal flooding exacerbated by climate change is recognised as a major global threat which is expected to impact more than a quarter of all people currently residing in Pacific Island countries. While most research in the last decade has focused on understanding the [...] Read more.

Coastal flooding exacerbated by climate change is recognised as a major global threat which is expected to impact more than a quarter of all people currently residing in Pacific Island countries. While most research in the last decade has focused on understanding the dynamics and impacts of future coastal flooding from extreme sea levels, the effects of relative sea level rise (RSLR) on exacerbating tsunami hazards are not well understood. Far-field or distant sourced tsunamis tend to have relatively lower impacts in Pacific Island states compared with locally sourced events, but there is limited understanding of how the impact of far-field tsunamis changes over time due to RSLR. Using the hydrodynamics software BG-Flood, we modelled the Tōhoku-oki tsunami from propagation to inundation in Samoa under incremental SLR to examine the effects that RSLR has on changing the exposure of the built environment (e.g., buildings) to a far-field tsunami. Outputs of maximum tsunami inundation and flow depth intensities which incorporate incremental SLR were then combined with digital representations of buildings and depth-damage functions in the RiskScape multi-hazard risk modelling software to assess the changes in building exposure over time. Results suggest that the impacts of Tōhoku-oki-type far-field tsunamis become significant once RSLR reaches 1 m above present levels. Present-day building exposure will increase by approx. 500% with 1 m RSLR by 2080–2130, and approx. 2350% with 2 m RSLR by as early as 2130–2140. These findings provide useful insights for application to tsunami hazard risk assessments under changing sea level conditions in analogous island environments. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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16 pages, 5089 KiB

Open AccessArticle

Mapping Dependence between Extreme Skew-Surge, Rainfall, and River-Flow

by Scott A. Stephens and Wenyan Wu

J. Mar. Sci. Eng. 2022, 10(12), 1818; https://doi.org/10.3390/jmse10121818 - 25 Nov 2022

Cited by 1 | Viewed by 1220

Abstract

Flooding in coastal areas is a major global hazard, made worse during compound flood events, which occur when multiple flood-drivers, such as tide, sea surge, and fluvial and pluvial flooding, coincide. We use 12 sea-level, 2065 rainfall, and 81 river-flow records to assess [...] Read more.

Flooding in coastal areas is a major global hazard, made worse during compound flood events, which occur when multiple flood-drivers, such as tide, sea surge, and fluvial and pluvial flooding, coincide. We use 12 sea-level, 2065 rainfall, and 81 river-flow records to assess the dependence of (1) extreme skew-surge and extreme rainfall (pluvial/surface runoff) and (2) extreme skew-surge and extreme river-flow (fluvial discharge) in New Zealand. We found that (1) skew-surge and rainfall and (2) skew-surge and river-flow are significantly, but not strongly, correlated in NZ. When spatially averaged to within 30 km of sea-level gauge location, the correlation was generally significant and positive, but weak with Kendall’s rank correlation coefficient τ < 0.3. We identify the weather types driving regional patterns of dependence. Trough weather types were the dominant driver of individual and coincident extreme events. Blocking weather types were associated with the highest extreme skew-surge and rainfall events along the northeast coast of the North Island and, consequently, were associated with a high proportion of coincident skew-surge/rainfall and skew-surge/river-flow events there. These findings have important implications for flood management, emergency response, and the insurance sector because impacts and losses may be correlated in space. Our findings add to a growing understanding of compound flooding worldwide for different geographical and meteorological settings. The positive dependence observed suggests that more attention to compound event probabilities is warranted when undertaking localized coastal-flood modelling. Full article

(This article belongs to the Special Issue Coastal Flooding: Causes, Impacts and Mitigation)

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