scholarly journals Dependence between high sea-level and high river discharge increases flood hazard in global deltas and estuaries

2018 ◽  
Vol 13 (8) ◽  
pp. 084012 ◽  
Author(s):  
Philip J Ward ◽  
Anaïs Couasnon ◽  
Dirk Eilander ◽  
Ivan D Haigh ◽  
Alistair Hendry ◽  
...  
Keyword(s):  
Sea Level ◽  
River Discharge ◽  
Flood Hazard

scholarly journals Measuring compound flood potential from river discharge and storm surge extremes at the global scale

2020 ◽  
Vol 20 (2) ◽  
pp. 489-504 ◽  
Author(s):  
Anaïs Couasnon ◽  
Dirk Eilander ◽  
Sanne Muis ◽  
Ted I. E. Veldkamp ◽  
Ivan D. Haigh ◽  
...  
Keyword(s):  
Storm Surge ◽  
River Discharge ◽  
Flood Hazard ◽  
Joint Probability ◽  
Global Scale ◽  
Statistical Dependence ◽  
Dependence Structure ◽  
Meteorological Forcing ◽  
Continental Scale ◽  
Bivariate Dependence

Abstract. The interaction between physical drivers from oceanographic, hydrological, and meteorological processes in coastal areas can result in compound flooding. Compound flood events, like Cyclone Idai and Hurricane Harvey, have revealed the devastating consequences of the co-occurrence of coastal and river floods. A number of studies have recently investigated the likelihood of compound flooding at the continental scale based on simulated variables of flood drivers, such as storm surge, precipitation, and river discharges. At the global scale, this has only been performed based on observations, thereby excluding a large extent of the global coastline. The purpose of this study is to fill this gap and identify regions with a high compound flooding potential from river discharge and storm surge extremes in river mouths globally. To do so, we use daily time series of river discharge and storm surge from state-of-the-art global models driven with consistent meteorological forcing from reanalysis datasets. We measure the compound flood potential by analysing both variables with respect to their timing, joint statistical dependence, and joint return period. Our analysis indicates many regions that deviate from statistical independence and could not be identified in previous global studies based on observations alone, such as Madagascar, northern Morocco, Vietnam, and Taiwan. We report possible causal mechanisms for the observed spatial patterns based on existing literature. Finally, we provide preliminary insights on the implications of the bivariate dependence behaviour on the flood hazard characterisation using Madagascar as a case study. Our global and local analyses show that the dependence structure between flood drivers can be complex and can significantly impact the joint probability of discharge and storm surge extremes. These emphasise the need to refine global flood risk assessments and emergency planning to account for these potential interactions.

The impact of glaciation, river-discharge and sea-level change on Late Quaternary environments in the southwestern Kara Sea

2000 ◽  
Vol 89 (3) ◽  
pp. 550-562 ◽  
Author(s):  
Leonid Polyak ◽  
Mikhail Levitan ◽  
Valery Gataullin ◽  
Tatiana Khusid ◽  
Valery Mikhailov ◽  
...  
Keyword(s):  
Sea Level ◽  
River Discharge ◽  
Late Quaternary ◽  
Sea Level Change ◽  
Kara Sea ◽  
Level Change ◽  
The Impact ◽  
And Sea Level

scholarly journals Impact of climate change on New York City’s coastal flood hazard: Increasing flood heights from the preindustrial to 2300 CE

2017 ◽  
Vol 114 (45) ◽  
pp. 11861-11866 ◽  
Author(s):  
Andra J. Garner ◽  
Michael E. Mann ◽  
Kerry A. Emanuel ◽  
Robert E. Kopp ◽  
Ning Lin ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
Sea Level Rise ◽  
Sea Level ◽  
Tropical Cyclones ◽  
York City ◽  
Flood Hazard ◽  
Storm Surges ◽  
Cmip5 Models ◽  
Tidal Level

The flood hazard in New York City depends on both storm surges and rising sea levels. We combine modeled storm surges with probabilistic sea-level rise projections to assess future coastal inundation in New York City from the preindustrial era through 2300 CE. The storm surges are derived from large sets of synthetic tropical cyclones, downscaled from RCP8.5 simulations from three CMIP5 models. The sea-level rise projections account for potential partial collapse of the Antarctic ice sheet in assessing future coastal inundation. CMIP5 models indicate that there will be minimal change in storm-surge heights from 2010 to 2100 or 2300, because the predicted strengthening of the strongest storms will be compensated by storm tracks moving offshore at the latitude of New York City. However, projected sea-level rise causes overall flood heights associated with tropical cyclones in New York City in coming centuries to increase greatly compared with preindustrial or modern flood heights. For the various sea-level rise scenarios we consider, the 1-in-500-y flood event increases from 3.4 m above mean tidal level during 1970–2005 to 4.0–5.1 m above mean tidal level by 2080–2100 and ranges from 5.0–15.4 m above mean tidal level by 2280–2300. Further, we find that the return period of a 2.25-m flood has decreased from ∼500 y before 1800 to ∼25 y during 1970–2005 and further decreases to ∼5 y by 2030–2045 in 95% of our simulations. The 2.25-m flood height is permanently exceeded by 2280–2300 for scenarios that include Antarctica’s potential partial collapse.

scholarly journals Compounding effects of sea level rise and fluvial flooding

2017 ◽  
Vol 114 (37) ◽  
pp. 9785-9790 ◽  
Author(s):  
Hamed R. Moftakhari ◽  
Gianfausto Salvadori ◽  
Amir AghaKouchak ◽  
Brett F. Sanders ◽  
Richard A. Matthew
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Hazard Assessment ◽  
Failure Probability ◽  
River Flow ◽  
Flood Hazard ◽  
High Tide ◽  
Probability Method ◽  
Flood Hazards ◽  
Flood Hazard Assessment

Sea level rise (SLR), a well-documented and urgent aspect of anthropogenic global warming, threatens population and assets located in low-lying coastal regions all around the world. Common flood hazard assessment practices typically account for one driver at a time (e.g., either fluvial flooding only or ocean flooding only), whereas coastal cities vulnerable to SLR are at risk for flooding from multiple drivers (e.g., extreme coastal high tide, storm surge, and river flow). Here, we propose a bivariate flood hazard assessment approach that accounts for compound flooding from river flow and coastal water level, and we show that a univariate approach may not appropriately characterize the flood hazard if there are compounding effects. Using copulas and bivariate dependence analysis, we also quantify the increases in failure probabilities for 2030 and 2050 caused by SLR under representative concentration pathways 4.5 and 8.5. Additionally, the increase in failure probability is shown to be strongly affected by compounding effects. The proposed failure probability method offers an innovative tool for assessing compounding flood hazards in a warming climate.

scholarly journals Measuring compound flood potential from river discharge and storm surge extremes at the global scale and its implications for flood hazard

2019 ◽  
Author(s):  
Anaïs Couasnon ◽  
Dirk Eilander ◽  
Sanne Muis ◽  
Ted I. E. Veldkamp ◽  
Ivan D. Haigh ◽  
...  
Keyword(s):  
Storm Surge ◽  
River Discharge ◽  
Flood Hazard ◽  
Joint Probability ◽  
Global Scale ◽  
Statistical Dependence ◽  
Dependence Structure ◽  
Meteorological Forcing ◽  
Continental Scale ◽  
Bivariate Dependence

Abstract. The interaction between physical drivers from oceanographic, hydrological, and meteorological processes in coastal areas can result in compound flooding. Compound flood events, like Cyclone Idai and Hurricane Harvey, have revealed the devastating consequences of the co-occurrence of coastal and river floods. A number of studies have recently investigated the likelihood of compound flooding at the continental scale based on simulated variables of flood drivers such as storm surge, precipitation, and river discharges. At the global scale, this has only been performed based on observations, thereby excluding a large extent of the global coastline. The purpose of this study is to fill this gap and identify potential hotspots of compound flooding from river discharge and storm surge extremes in river mouths globally. To do so, we use daily time-series of river discharge and storm surge from state-of-the-art global models driven with consistent meteorological forcing from reanalysis datasets. We measure the compound flood potential by analysing both variables with respect to their timing, joint statistical dependence, and joint return period. We find many hotspot regions of compound flooding that could not be identified in previous global studies based on observations alone, such as: Madagascar, Northern Morocco, Vietnam, and Taiwan. We report possible causal mechanisms for the observed spatial patterns based on existing literature. Finally, we provide preliminary insights on the implications of the bivariate dependence behaviour on the flood hazard characterisation using Madagascar as a case study. Our global and local analyses show that the dependence structure between flood drivers can be complex and can significantly impact the joint probability of discharge and storm surge extremes. These emphasise the need to refine global flood risk assessments and emergency planning to account for these potential interactions.

scholarly journals Impact of Barrier Breaching on Wetland Ecosystems under the Influence of Storm Surge, Sea-Level Rise and Freshwater Discharge

Wetlands ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 771-785 ◽  
Author(s):  
Xiaorong Li ◽  
Nicoletta Leonardi ◽  
Andrew J. Plater
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
River Discharge ◽  
Coastal Wetland ◽  
Storm Surges ◽  
Wetland Ecology ◽  
Barrier Beach ◽  
Wetland Ecosystems ◽  
Wetland Habitats

Abstract Coastal wetland ecosystems and biodiversity are susceptible to changes in salinity brought about by the local effects of climate change, meteorological extremes, coastal evolution and human intervention. This study investigates changes in the salinity of surface water and the associated impacts on back-barrier wetlands as a result of breaching of a barrier beach and under the compound action of different surge heights, accelerated sea-level rise (SLR), river discharge and rainfall. We show that barrier breaching can have significant effects in terms of vegetation die-back even without the occurrence of large storm surges or in the absence of SLR, and that rainfall alone is unlikely to be sufficient to mitigate increased salinity due to direct tidal flushing. Results demonstrate that an increase in sea level corresponding to the RCP8.5 scenario for year 2100 causes a greater impact in terms of reedbed loss than storm surges up to 2 m with no SLR. In mitigation of the consequent changes in wetland ecology, regulation of relatively small and continuous river discharge can be regarded as a strategy for the management of coastal back-barrier wetland habitats and for the maintenance of brackish ecosystems. As such, this study provides a tool for scoping the potential impacts of storms, climate change and alternative management strategies on existing wetland habitats and species.

Saltwater intrusion in delta regions around the globe

2020 ◽  
Author(s):  
Jonas Götte ◽  
Josefin Thorslund ◽  
Niko Wanders
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
River Discharge ◽  
Saltwater Intrusion ◽  
Input Data ◽  
Salt Water ◽  
Global Scale ◽  
Natural Phenomenon ◽  
Salt Water Intrusion ◽  
Ensemble Simulations

<p>Saltwater intrusion into estuaries is a natural phenomenon which impacts freshwater availability for irrigation and human consumption. The intrusion length is dependent on the river discharge, sea level fluctuation and deltaic shape. As climate change impacts the sea level fluctuations and river discharge in many areas in the world it is expected that the intrusion length of rivers will change in the coming decades. However, global scale assessments are currently lacking, since estimates of the intrusion length are usually done for individual rivers, with complex models requiring extensive spatio-temporal data.<br>In this study, we provide a first global estimate of saltwater intrusion in estuaries. To do this, we first evaluate an existing predictive model for the salt water intrusion length on a local scale, before transitioning to global input data of river discharge, deltaic shapes and sea level. We assess the predictive quality of the model and its sensitivity in regard to uncertainties in (global) input data before giving an estimate of salt intrusion globally.<br>By using large ensemble-simulations of discharge on a global scale in a warmer climate (+2 °C), we further project impacts of climate change on the saltwater intrusion length and identify highly affected delta systems. The ensemble-simulations allow extreme events and respective estimations of frequency and magnitude. This is especially relevant since high salinity levels usually occur during droughts when river discharge is low and freshwater resources are diminished.</p>

Assessing the global risk of climate change to re/insurers using catastrophe models and hazard maps

2020 ◽  
Author(s):  
Sarah Jones ◽  
Emma Raven ◽  
Jane Toothill
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Flood Risk ◽  
River Flow ◽  
Climate Model ◽  
Flood Hazard ◽  
Insurance Industry ◽  
Global Climate Model ◽  
Hazard Maps ◽  
The Impact

<p>In 2018 worldwide natural catastrophe losses were estimated at around USD $155 billion, resulting in the fourth-highest insurance payout on sigma records, and in 2020 JBA Risk Management (JBA) estimate 2 billion people will be at risk to inland flooding. By 2100, under a 1.5°C warming scenario, the cost of coastal flooding alone as a result of sea level rise could reach USD $10.2 trillion per year, assuming no further adaptation. It is therefore imperative to understand the impact climate change may have on global flood risk and insured losses in the future.</p><p>The re/insurance industry has an important role to play in providing financial resilience in a changing climate. Although integrating climate science into financial business remains in its infancy, modelling companies like JBA are increasingly developing new data and services to help assess the potential impact of climate change on insurance exposure.</p><p>We will discuss several approaches to incorporating climate change projections with flood risk data using examples from research collaborations and commercial projects. Our case studies will include: (1) building a national-scale climate change flood model through the application of projected changes in river flow, rainfall and sea level to the stochastic event set in the model, and (2) using Global Climate Model data to adjust hydrological inputs driving 2D hydraulic models to develop climate change flood hazard maps.</p><p>These tools provide outputs to meet different needs, and results may sometimes invoke further questions. For example: how can an extreme climate scenario produce lower flood risk than a conservative one? Why may adjacent postcodes' flood risk differ? We will explore the challenges associated with interpreting these results and the potential implications for the re/insurance industry.</p>

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