scholarly journals Sensitivity of Estuaries to Compound Flooding

2021 ◽  
Author(s):  
Lisa M. Harrison ◽  
Tom J. Coulthard ◽  
Peter E. Robins ◽  
Matthew J. Lewis
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Extreme Events ◽  
Mitigation Strategies ◽  
Flood Mitigation ◽  
Relative Timing ◽  
Impact Modelling ◽  
Flooding Hazards ◽  
Fluvial Response ◽  
Outer Estuary

AbstractFluvial and surge-tide extremes can occur synchronously resulting in compound flooding in estuaries, greatly intensifying the hazard. This flood risk has the potential to increase in the future as the frequency, phasing and/or intensity of these drivers change. Improved understanding of how extreme fluvial discharge and surge-tides interact will help inform future flood mitigation methodology. In this paper, therefore, we resolve for the first time intra-estuary sensitivities to fluvial and surge-tide extremes, for two contrasting UK estuaries (Humber and Dyfi). Model simulations at hyper-spatial resolution (< 50 m) using a 2D hydrodynamic model predicted compound flooding hazards based on: (1) present-day extreme events (worst on record); (2) present-day extreme events with shifted timings of the drivers to maximise flooding; and (3) modified drivers representing projected climate change. We found that in a small estuary with short-duration, high-intensity fluvial inputs (Dyfi), flood extent is 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 a larger estuary with a slower fluvial response to rainfall (Humber). In the Humber, extreme fluvial inputs during a compound hazard actually reduced maximum water depths in the outer estuary, compared with a surge-tide-only event. Projected future changes in these drivers by 2100 will increase compound flooding hazards: simulated sea-level rise scenarios predicted substantial and widespread flooding in both estuaries. However, projected increases in surge-tide behaved differently to sea-level rise of the same magnitude, resulting in a greater seawater influx and more flooding. Increased fluvial volumes were the weakest driver of estuarine flooding. In this paper we show how these interactions are complex and how the hydrodynamics vary considerably between different estuaries and sites within estuaries, making it difficult to generalise, use probabilistic or use 1D approaches for assessing compound flooding hazards. Hence, we contribute new knowledge and methods for catchment-to-coast impact modelling used for flood mitigation strategies.

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

&lt;p&gt;Coastal flooding worldwide causes the vast majority of natural disasters; for the UK costing &amp;#163;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 &amp;#8211; now and in the future &amp;#8211; 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 (&lt;50&amp;#160;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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;

Guidance for Human Action Evaluations for External Flood Risk Assessment

2016 ◽  
Author(s):  
Raymond E. Schneider ◽  
Srinivasa Visweswaran ◽  
John Fluehr ◽  
H. Alan Hackerott
Keyword(s):  
Risk Assessment ◽  
Ad Hoc ◽  
Human Action ◽  
Mitigation Strategies ◽  
Flood Mitigation ◽  
Human Reliability Analysis ◽  
Factors Affecting ◽  
Investment Protection ◽  
Performance Shaping Factors ◽  
Flooding Hazards

For many years external flooding hazards have been recognized as significant contributors to plant risk. However, it was not until the events at Fukushima that there was a concerted effort on the part of the utilities to reassess the plant external flood design basis, identify external flood vulnerabilities and take actions to address them. For many plants, resolution of low probability high consequence floods will likely be addressed by a combination of actions involving enhancements to flood protection and hazard mitigation strategies. Over time, as plants decide on which strategies to apply there is an expectation that the most effective way to develop and justify these strategies will involve probabilistic risk assessment (PRA) concepts. The PRA framework is well suited for performing a human reliability analysis (HRA). Within that framework, HRA evaluations focus on operator and plant staff actions taken in response to plant initiating events (e.g., loss of offsite power, etc.). For many external floods, advance warning of an impending external flood event provides the trigger for pre-emptive manual actions to potentially reconfigure the plant through temporary installation of flood barriers. Unlike the post-initiator actions which tend to be more narrowly focused, these pre-emptive actions are taken in a less controlled environment, may be ad hoc, and may potentially be in competition with site investment protection activities, site evacuation, etc. The purpose of this paper is to define the challenges in defining an approach for treating external flood actions, identifying external flood timelines, identifying the manual actions/organizational environment during external flooding scenarios and proposing an integrated strategy for quantifying those actions. The proposed quantification process is rooted in management science concepts for evaluating project reliability. The overall methodology identifies flood significant performance shaping factors, and identifies three (3) factors, namely time available for flood mitigation, proper access to plant site following flood and environmental factors, as having an overarching impact on the performance shaping factors affecting each of the flood mitigation tasks.

Coastal flooding in the Balearic Islands during the 21st century caused by sea level rise and extreme events

2020 ◽  
Author(s):  
Pau Luque Lozano ◽  
Lluís Gómez-Pujol ◽  
Marta Marcos ◽  
Alejandro Orfila
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Extreme Events ◽  
Storm Surges ◽  
Coastal Flooding ◽  
Coastal Areas ◽  
Balearic Islands ◽  
Mean Sea Level

&lt;p&gt;Sea-level rise induces a permanent loss of land with widespread ecological and economic impacts, most evident in urban and densely populated areas. The eventual coastline retreat combined with the action of waves and storm surges will end in more severe damages over coastal areas. These effects are expected to be particularly significant over islands, where coastal zones represent a relatively larger area vulnerable to marine hazards.&lt;/p&gt;&lt;p&gt;Managing coastal flood risk at regional scales requires a prioritization of resources and socioeconomic activities along the coast. Stakeholders, such as regional authorities, coastal managers and private companies, need tools that help to address the evaluation of coastal risks and criteria to support decision-makers to clarify priorities and critical sites. For this reason, the regional Government of the Balearic Islands (Spain) in association with the Spanish Ministry of Agriculture, Fisheries and Environment has launched the Plan for Climate Change Coastal Adaptation. This framework integrates two levels of analysis. The first one relates with the identification of critical areas affected by coastal flooding and erosion under mean sea-level rise scenarios and the quantification of the extent of flooding, including marine extreme events. The second level assesses the impacts on infrastructures and assets from a socioeconomic perspective due to these hazards.&lt;/p&gt;&lt;p&gt;In this context, this paper quantifies the effects of sea-level rise and marine extreme events caused by storm surges and waves along the coasts of the Balearic Islands (Western Mediterranean Sea) in terms of coastal flooding and potential erosion. Given the regional scale (~1500 km) of this study, the presented methodology adopts a compromise between accuracy, physical representativity and computational costs. We map the projected flooded coastal areas under two mean sea-level rise climate change scenarios, RCP4.5 and RCP8.5. To do so, we apply a corrected bathtub algorithm. Additionally, we compute the impact of extreme storm surges and waves using two 35-year hindcasts consistently forced by mean sea level pressure and surface winds from ERA-Interim reanalysis. Waves have been further propagated towards the nearshore to compute wave setup with higher accuracy. The 100-year return levels of joint storm surges and waves are used to map the spatial extent of flooding in more than 200 sandy beaches around the Balearic Islands by mid and late 21st century, using the hydrodynamical LISFLOOD-FP model and a high resolution (2 m) Digital Elevation Model.&lt;/p&gt;

Climate Change Mitigation

2017 ◽  
pp. 64-76 ◽  
Author(s):  
Nishi Srivastava
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Sea Level Rise ◽  
Sea Level ◽  
Climate Change Mitigation ◽  
Mitigation Strategies ◽  
Earth System ◽  
Green House Gases ◽  
Green House ◽  
Change Mitigation

Climate change caused due to our careless activities towards our nature, ecosystem, and whole earth system. We are paying and will be paying in future for our irresponsible activities in past and present. Increased concentration of Green House Gases (GHG) has caused severe global warming which will cause melting of glacier and results in sea level rise. To avoid and reduce the intensity and severity of global warming and climate change, its mitigation is essential. In this chapter we have focused on various issues related with climate change and mitigation strategies.

scholarly journals Compound flood potential from storm surge and heavy precipitation in coastal China: dependence, drivers, and impacts

2021 ◽  
Vol 25 (8) ◽  
pp. 4403-4416
Author(s):  
Jiayi Fang ◽  
Thomas Wahl ◽  
Jian Fang ◽  
Xun Sun ◽  
Feng Kong ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Extreme Events ◽  
Precipitable Water ◽  
Heavy Precipitation ◽  
South Eastern ◽  
Significant Dependence ◽  
Strong Winds ◽  
Flooding Events

Abstract. The interaction between storm surge and concurrent precipitation is poorly understood in many coastal regions. This paper investigates the potential compound effects from these two flooding drivers along the coast of China for the first time by using the most comprehensive records of storm surge and precipitation. Statistically significant dependence between flooding drivers exists at the majority of locations that are analysed, but the strength of the correlation varies spatially and temporally and depending on how extreme events are defined. In general, we find higher dependence at the south-eastern tide gauges (TGs) (latitude < 30∘ N) compared to the northern TGs. Seasonal variations in the dependence are also evident. Overall there are more sites with significant dependence in the tropical cyclone (TC) season, especially in the summer. Accounting for past sea level rise further increases the dependence between flooding drivers, and future sea level rise will hence likely lead to an increase in the frequency of compound events. We also find notable differences in the meteorological patterns associated with events where both drivers are extreme versus events where only one driver is extreme. Events with both extreme drivers at south-eastern TG sites are caused by low-pressure systems with similar characteristics across locations, including high precipitable water content (PWC) and strong winds that generate high storm surge. Based on historical disaster damages records of Hong Kong, events with both extreme drivers account for the vast majority of damages and casualties, compared to univariate flooding events, where only one flooding driver occurred. Given the large coastal population and low capacity of drainage systems in many Chinese urban coastal areas, these findings highlight the necessity to incorporate compound flooding and its potential changes in a warming climate into risk assessments, urban planning, and the design of coastal infrastructure and flood defences.

Climate Change Mitigation

2016 ◽  
pp. 427-439
Author(s):  
Nishi Srivastava
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Sea Level Rise ◽  
Sea Level ◽  
Climate Change Mitigation ◽  
Mitigation Strategies ◽  
Earth System ◽  
Green House Gases ◽  
Green House ◽  
Change Mitigation

Climate change caused due to our careless activities towards our nature, ecosystem, and whole earth system. We are paying and will be paying in future for our irresponsible activities in past and present. Increased concentration of Green House Gases (GHG) has caused severe global warming which will cause melting of glacier and results in sea level rise. To avoid and reduce the intensity and severity of global warming and climate change, its mitigation is essential. In this chapter we have focused on various issues related with climate change and mitigation strategies.

California’s coastal development: Sea-level rise and extreme events — where do we go from here?

Shore & Beach ◽  
2019 ◽  
pp. 15-28 ◽  
Author(s):  
Gary Griggs ◽  
Kiki Patsch
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Extreme Events ◽  
Land Use Planning ◽  
Trigger Points ◽  
Coastal Development ◽  
Storm Wave ◽  
Coastal Land Use ◽  
Run Up ◽  
Coastal Land

As sea level continues to rise at an accelerated rate, California’s intensive coastal development and infrastructure is coming under an increasing threat. Whether lowelevation shoreline areas that are subject to flooding at extreme tides and times of storm wave run-up, or construction on eroding bluffs or cliffs, the risks will continue to increase from extreme events but, over the longer term, from continuing sea-level rise. Future sea-level rise values under different greenhouse gas scenarios have recently been projected and adopted by the state to be used in coastal land use planning and decision making. While beach nourishment can provide very short-term protection, and seawalls and revetments can provide somewhat longer-term protection, they both come with significant costs and also environmental impacts. The era of routine armor emplacement is coming to an end in California, and whether designated as relocation or managed retreat, now is the time to make the difficult decisions on how this will be accomplished and what the trigger points will be to initiate the response.

scholarly journals Quantifying the effect of sea level rise and flood defence – a point process perspective on coastal flood damage

2016 ◽  
Vol 16 (2) ◽  
pp. 559-576 ◽  
Author(s):  
M. Boettle ◽  
D. Rybski ◽  
J. P. Kropp
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Point Process ◽  
Extreme Events ◽  
Global Scale ◽  
Flood Damage ◽  
Greenhouse Gas Mitigation ◽  
Sea Levels ◽  
Stochastic Framework ◽  
Process Perspective

Abstract. In contrast to recent advances in projecting sea levels, estimations about the economic impact of sea level rise are vague. Nonetheless, they are of great importance for policy making with regard to adaptation and greenhouse-gas mitigation. Since the damage is mainly caused by extreme events, we propose a stochastic framework to estimate the monetary losses from coastal floods in a confined region. For this purpose, we follow a Peak-over-Threshold approach employing a Poisson point process and the Generalised Pareto Distribution. By considering the effect of sea level rise as well as potential adaptation scenarios on the involved parameters, we are able to study the development of the annual damage. An application to the city of Copenhagen shows that a doubling of losses can be expected from a mean sea level increase of only 11 cm. In general, we find that for varying parameters the expected losses can be well approximated by one of three analytical expressions depending on the extreme value parameters. These findings reveal the complex interplay of the involved parameters and allow conclusions of fundamental relevance. For instance, we show that the damage typically increases faster than the sea level rise itself. This in turn can be of great importance for the assessment of sea level rise impacts on the global scale. Our results are accompanied by an assessment of uncertainty, which reflects the stochastic nature of extreme events. While the absolute value of uncertainty about the flood damage increases with rising mean sea levels, we find that it decreases in relation to the expected damage.

Rapid deforestation of a coastal landscape driven by sea level rise and extreme events

2021 ◽  
Author(s):  
Emily A. Ury ◽  
Xi Yang ◽  
Justin P. Wright ◽  
Emily S. Bernhardt
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Extreme Events ◽  
Coastal Landscape

scholarly journals An examination of land use impacts of flooding induced by sea level rise

2017 ◽  
Vol 17 (3) ◽  
pp. 315-334 ◽  
Author(s):  
Jie Song ◽  
Xinyu Fu ◽  
Yue Gu ◽  
Yujun Deng ◽  
Zhong-Ren Peng
Keyword(s):  
Land Use ◽  
Sea Level Rise ◽  
Sea Level ◽  
Urban Growth ◽  
Flood Mitigation ◽  
Coastal Hazards ◽  
Land Use Impacts ◽  
Study Region ◽  
Sea Levels ◽  
Modeling Uncertainties

Abstract. Coastal regions become unprecedentedly vulnerable to coastal hazards that are associated with sea level rise. The purpose of this paper is therefore to simulate prospective urban exposure to changing sea levels. This article first applied the cellular-automaton-based SLEUTH model (Project Gigalopolis, 2016) to calibrate historical urban dynamics in Bay County, Florida (USA) – a region that is greatly threatened by rising sea levels. This paper estimated five urban growth parameters by multiple-calibration procedures that used different Monte Carlo iterations to account for modeling uncertainties. It then employed the calibrated model to predict three scenarios of urban growth up to 2080 – historical trend, urban sprawl, and compact development. We also assessed land use impacts of four policies: no regulations; flood mitigation plans based on the whole study region and on those areas that are prone to experience growth; and the protection of conservational lands. This study lastly overlaid projected urban areas in 2030 and 2080 with 500-year flooding maps that were developed under 0, 0.2, and 0.9 m sea level rise. The calibration results that a substantial number of built-up regions extend from established coastal settlements. The predictions suggest that total flooded area of new urbanized regions in 2080 would be more than 25 times that under the flood mitigation policy, if the urbanization progresses with few policy interventions. The joint model generates new knowledge in the domain between land use modeling and sea level rise. It contributes to coastal spatial planning by helping develop hazard mitigation schemes and can be employed in other international communities that face combined pressure of urban growth and climate change.

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