scholarly journals National-Scale Built-Environment Exposure to 100-Year Extreme Sea Levels and Sea-Level Rise

2020 ◽  
Vol 12 (4) ◽  
pp. 1513 ◽  
Author(s):  
Ryan Paulik ◽  
Scott Stephens ◽  
Robert Bell ◽  
Sanjay Wadhwa ◽  
Ben Popovich
Keyword(s):  
Built Environment ◽  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Flooding ◽  
National Scale ◽  
Model Framework ◽  
Sea Levels ◽  
Environment Exposure ◽  
Flood Exposure ◽  
Extreme Sea Levels

Coastal flooding from extreme sea levels will increase in frequency and magnitude as global climate change forces sea-level rise (SLR). Extreme sea-level events, rare in the recent past (i.e., once per century), are projected to occur at least once per year by 2050 along many of the world’s coastlines. Information showing where and how built-environment exposure increases with SLR, enables timely adaptation before damaging thresholds are reached. This study presents a first national-scale assessment of New Zealand’s built-environment exposure to future coastal flooding. We use an analytical risk model framework, “RiskScape”, to enumerate land, buildings and infrastructure exposed to a present and future 100-year extreme sea-level flood event (ESL100). We used high-resolution topographic data to assess incremental exposure to 0.1 m SLR increases. This approach detects variable rates in the potential magnitude and timing of future flood exposure in response to SLR over decadal scales. National built-land and asset exposure to ESL100 flooding doubles with less than 1 m SLR, indicating low-lying areas are likely to experience rapid exposure increases from modest increases in SLR expected within the next few decades. This highlights an urgent need for national and regional actions to anticipate and adaptively plan to reduce future socio-economic impacts arising from flood exposure to extreme sea-levels and SLR.

scholarly journals A National-Scale Assessment of Population and Built-Environment Exposure in Tsunami Evacuation Zones

Geosciences ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 291
Author(s):  
Ryan Paulik ◽  
Heather Craig ◽  
Benjamin Popovich
Keyword(s):  
Built Environment ◽  
Risk Model ◽  
Residential Buildings ◽  
Age Groups ◽  
Road Transport ◽  
Transport Network ◽  
National Scale ◽  
Model Framework ◽  
Scale Assessment ◽  
Environment Exposure

Evacuation zones are a critical tool for mitigating loss of life in tsunami events. In New Zealand, tsunami evacuation zones are implemented by emergency management agencies at regional or sub-regional scales, providing national coverage for populated coastlines at risk to tsunami inundation. In this study, we apply the exposure component of a risk model framework (RiskScape) to deliver a first national-scale assessment of New Zealand’s population and built-environment exposure in tsunami evacuation zones. Usually-resident populations, buildings, land and transport network components are identified at an asset level and enumerated at national and regional scales. Evacuation zones are occupied by just under 10% of New Zealand’s population, residing in 399,000 residential buildings. These are supported by a further 5400 critical buildings and 6300 km of road transport network. Approximately 40% of exposed populations and buildings occupy evacuation zones expected to be inundated once every 500 years. This includes over 150,000 people in highly vulnerable age groups, i.e., children and elderly. The complex arrangement of built environments highlights a need for disaster risk managers to proactively identify and prepare populations for evacuation based on their vulnerability to harm from tsunami and ability to access resources for recovery after the event.

Multiple drivers of extreme sea levels in the northern Adriatic Sea

2021 ◽  
Author(s):  
Christian Ferrarin ◽  
Piero Lionello ◽  
Mirko Orlic ◽  
Fabio Raicich ◽  
Gianfausto Salvadori
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Adriatic Sea ◽  
Driving Factors ◽  
Northern Adriatic Sea ◽  
Relative Sea Level ◽  
Northern Adriatic ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
Relative Sea Level Rise

<p><span><span>Extreme sea levels at the coast result from the combination of astronomical tides with atmospherically forced fluctuations at multiple time scales. Seiches, river floods, waves, inter-annual and inter-decad</span></span><span><span>al dynamics and relative sea-level rise can also contribute to the total sea level. While tides are usually well described and predicted, the effect of the different atmospheric contributions to the sea level and their trends are still not well understood. Meso-scale atmospheric disturbances, synoptic-scale phenomena and planetary atmospheric waves (PAW) act at different temporal and spatial scales and thus generate sea-level disturbances at different frequencies. In this study, we analyze the 1872-2019 sea-level time series in Venice (northern Adriatic Sea, Italy) to investigate the relative role of the different driving factors in the extreme sea levels distribution. The adopted approach consists in 1) isolating the different contributions to the sea level by applying least-squares fitting and Fourier decomposition; 2) performing a multivariate statistical analysis which enables the dependencies among driving factors and their joint probability of occurrence to be described; 3) analyzing temporal changes in extreme sea levels and extrapolating possible future tendencies. The results highlight the fact that the most extreme sea levels are mainly dominated by the non-tidal residual, while the tide plays a secondary role. The non-tidal residual of the extreme sea levels is attributed mostly to PAW surge and storm surge, with the latter component becoming dominant for the most extreme events. The results of temporal evolution analysis confirm previous studies according to which the relative sea-level rise is the major driver of the increase in the frequency of floods in Venice over the last century. However, also long term variability in the storm activity impacted the frequency and intensity of extreme sea levels and have contributed to an increase of floods in Venice during the fall and winter months of the last three decades.</span></span></p>

Interactions of extreme river flows and sea levels for coastal flooding

2020 ◽  
Author(s):  
Peter Robins ◽  
Lisa Harrison ◽  
Mariam Elnahrawi ◽  
Matt Lewis ◽  
Tom Coulthard ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
West Coast ◽  
Flood Risk ◽  
Coastal Flooding ◽  
Relative Timing ◽  
The West ◽  
Sea Levels ◽  
Flooding Hazards ◽  
Fluvial Response

<p>Coastal flooding worldwide causes the vast majority of natural disasters; for the UK costing £2.2 billion/year. Fluvial and surge-tide extremes can occur synchronously resulting in combination flooding hazards in estuaries, intensifying the flood risk beyond fluvial-only or surge-only events. Worse, this flood risk has the potential to increase further in the future as the frequency and/or intensity of these drivers change, combined with projected sea-level rise. Yet, the sensitivity of contrasting estuaries to combination and compound flooding hazards at sub-daily scales – now and in the future – is unclear. Here, we investigate the dependence between fluvial and surge interactions at sub-daily scales for contrasting catchment and estuary types (Humber vs. Dyfi, UK), using 50+ years of data: 15-min fluvial flows and hourly sea levels. Additionally, we simulate intra-estuary (<50 m resolution) sensitivities to combination flooding hazards based on: (1) realistic extreme events (worst-on-record); (2) realistic events with shifted timings of the drivers to maximise flooding; and (3) modified drivers representing projected climate change.</p><p>For well-documented flooding events, we show significant correlation between skew surge and peak fluvial flow, for the Dyfi (small catchment and estuary with a fast fluvial response on the west coast of Britain), with a higher dependence during autumn/winter months. In contrast, we show no dependence for the Humber (large catchment and estuary with a slow fluvial response on the east coast of Britain). Cross-correlation results, however, did show correlation with a time lag (~10 hours). For the Dyfi, flood extent was sensitive to the relative timing of the fluvial and surge-tide drivers. In contrast, the relative timing of these drivers did not affect flooding in the Humber. However, extreme fluvial flows in the Humber actually reduced water levels in the outer estuary, compared with a surge-only event. Projected future changes in these drivers by 2100 are likely to increase combination flooding hazards: sea-level rise scenarios predicted substantial and widespread flooding in both estuaries. However, similar increases in storm surge resulted in a greater seawater influx, altering the character of the flooding. Projected changes in fluvial volumes were the weakest driver of estuarine flooding. On the west coast of Britain containing many small/steep catchments, combination flooding hazards from fluvial and surges extremes occurring together is likely. Moreover, high-resolution data and hydrodynamic modelling are necessary to resolve the impact and inform flood mitigation methodology.</p>

scholarly journals Modelling the increased frequency of extreme sea levels in the Ganges–Brahmaputra–Meghna delta due to sea level rise and other effects of climate change

2015 ◽  
Vol 17 (7) ◽  
pp. 1311-1322 ◽  
Author(s):  
S. Kay ◽  
J. Caesar ◽  
J. Wolf ◽  
L. Bricheno ◽  
R. J. Nicholls ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Bay Of Bengal ◽  
Hydrodynamic Model ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
The Ganges

A hydrodynamic model of the Bay of Bengal has been used to explore increasing frequency of extreme sea levels in the Ganges–Brahmaputra–Meghna delta over the 21st century.

scholarly journals Unravelling the Importance of Uncertainties in Global-Scale Coastal Flood Risk Assessments under Sea Level Rise

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 774
Author(s):  
Jeremy Rohmer ◽  
Daniel Lincke ◽  
Jochen Hinkel ◽  
Gonéri Le Cozannet ◽  
Erwin Lambert ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Flood Risk ◽  
Global Scale ◽  
Short Term ◽  
Sea Levels ◽  
Coastal Flood ◽  
Extreme Sea Levels ◽  
Coastal Flood Risk ◽  
Adaptation Costs

Global scale assessments of coastal flood damage and adaptation costs under 21st century sea-level rise are associated with a wide range of uncertainties, including those in future projections of socioeconomic development (shared socioeconomic pathways (SSP) scenarios), of greenhouse gas concentrations (RCP scenarios), and of sea-level rise at regional scale (RSLR), as well as structural uncertainties related to the modelling of extreme sea levels, data on exposed population and assets, and the costs of flood damages, etc. This raises the following questions: which sources of uncertainty need to be considered in such assessments and what is the relative importance of each source of uncertainty in the final results? Using the coastal flood module of the Dynamic Interactive Vulnerability Assessment modelling framework, we extensively explore the impact of scenario, data and model uncertainties in a global manner, i.e., by considering a large number (>2000) of simulation results. The influence of the uncertainties on the two risk metrics of expected annual damage (EAD), and adaptation costs (AC) related to coastal protection is assessed at global scale by combining variance-based sensitivity indices with a regression-based machine learning technique. On this basis, we show that the research priorities in terms of future data/knowledge acquisition to reduce uncertainty on EAD and AC differ depending on the considered time horizon. In the short term (before 2040), EAD uncertainty could be significantly decreased by 25 and 75% if the uncertainty of the translation of physical damage into costs and of the modelling of extreme sea levels could respectively be reduced. For AC, it is RSLR that primarily drives short-term uncertainty (with a contribution ~50%). In the longer term (>2050), uncertainty in EAD could be largely reduced by 75% if the SSP scenario could be unambiguously identified. For AC, it is the RCP selection that helps reducing uncertainty (up to 90% by the end of the century). Altogether, the uncertainty in future human activities (SSP and RCP) are the dominant source of the uncertainty in future coastal flood risk.

scholarly journals A global analysis of subsidence, relative sea-level change and coastal flood exposure

2021 ◽  
Author(s):  
Daniel Lincke ◽  
Robert J. Nicholls ◽  
Jochen Hinkel ◽  
Sally Brown ◽  
Athanasios T. Vafeidis ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Global Analysis ◽  
Relative Sea Level ◽  
Sea Levels ◽  
Coastal Flood ◽  
Global Issue ◽  
Flood Exposure ◽  
Relative Sea Level Rise ◽  
Global Sea Level

<p>Climate-induced sea-level rise and vertical land movements, including natural and human-induced subsidence in sedimentary coastal lowlands, combine to change relative sea levels around the world's coast. Global-average coastal relative sea-level rise was 2.5 mm/yr over the last two decades. However, as coastal inhabitants are preferentially located in subsiding locations, they experience an average relative sea-level rise up to four times faster at 7.8 to 9.9 mm/yr. This first global quantification of relative sea-level rise shows that the resulting impacts, and adaptation needs are much higher than reported global sea-level rise measurements would suggest. Hence, coastal subsidence is an important global issue that needs more assessment and action. In particular, human-induced subsidence in and surrounding coastal cities can be rapidly reduced with appropriate policy measures for groundwater utilization and drainage. This offers substantial and rapid benefits in terms of reducing growth of coastal flood exposure due to relative sea-level rise.</p>

Coastal inundation hazard in the North Adriatic Sea under Climate Change

2020 ◽  
Author(s):  
Arthur Hrast Essenfelder ◽  
Mattia Amadio ◽  
Stefano Bagli ◽  
Paolo Mazzoli
Keyword(s):  
Sea Level ◽  
Adriatic Sea ◽  
Coastal Flooding ◽  
Short Term ◽  
Coastal Inundation ◽  
Mean Sea Level ◽  
Sea Levels ◽  
The North ◽  
Extreme Sea Levels ◽  
North Adriatic Sea

<p>On the 12<sup>th</sup> of November of 2019, flood levels in the Venice Lagoon have reached the mark of 1.87 metres, the second-highest level since records began in 1923. Although a recurrent problem in Venice, the significance of this event have raise awareness of the issue of coastal inundation hazard in Italy, particularly at the highly vulnerable territory of the regions facing the North Adriatic Sea. Several are the processes that contribute to a costal inundation event. On the short term, processes such as high tide and storm surge events can result in sea levels, potentially triggering devastating impacts on human settlements and activities. On the long term, the land subsidence and mean sea level (MSL) changes are important factors; in fact, in some regions such as Jakarta and Bangkok the land is expected to subside by more than 1 meter, while MSL is expected to rise during the next decades, reaching global mean absolute values ranging from 0.3–0.6m (RCP 2.6) to 0.5–1.1m (RCP 8.5) by the end of the century. The combined effect of global sea level rise, local subsidence, and short term phenomena can potentially increase the frequency and intensity of extreme sea levels (ESL), posing a major threat to coastal areas. Currently, almost 700 million people live in low-lying coastal areas, and about 13% of them are exposed to a 100-year flood. In Italy, a territory that is highly vulnerable to coastal flooding are the Regions facing the North Adriatic Sea, mainly due to two factors: the morphological characteristic of this territory, characterised by low-lying areas, and the bathymetry and shape of the Adriatic basin, which cause water level to accumulate and increase rapidly during storm surge events, especially during winter. In this paper, we evaluate two different coastal inundation modelling techniques, one hydrostatic (as part of the EIT Climate-KIC SaferPLACES project) and another hydrodynamic (the ANUGA model), by stressing the models with different ESL, both for the historical mean sea level and for MSL projections at 2050 and 2100. The two different inundation models are tested on three pilot sites particularly vulnerable to coastal flooding located in the North Adriatic Sea: Venice, Cesenatico, and Rimini. We compare our modelling results with existing hazard records and previous hazard and risk assessments. Finally, we apply a flood damage model developed for Italy to estimate the potential economic damages linked to the different flood scenarios, and we calculate the change in expected annual damages according to the relative extreme sea levels.</p>

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