scholarly journals Joint impact of rainfall and tidal level on flood risk in a coastal city with a complex river network: a case study of Fuzhou City, China

2013 ◽  
Vol 17 (2) ◽  
pp. 679-689 ◽  
Author(s):  
J. J. Lian ◽  
K. Xu ◽  
C. Ma
Keyword(s):  
Flood Risk ◽  
Joint Probability ◽  
Heavy Precipitation ◽  
River Network ◽  
Flood Frequency ◽  
Combined Effect ◽  
Multiple Sources ◽  
Tidal Level ◽  
Sea Levels ◽  
Coastal Cities

Abstract. Coastal cities are particularly vulnerable to flood under multivariable conditions, such as heavy precipitation, high sea levels, and storms. The combined effect of multiple sources and the joint probability of extremes should be considered to assess and manage flood risk better. This paper aims to study the combined effect of rainfall and the tidal level of the receiving water body on flood probability and severity in Fuzhou City, which has a complex river network. Flood severity under a range of precipitation intensities, with return periods (RPs) of 5 yr to 100 yr, and tidal levels was assessed through a hydrodynamic model verified by data observed during Typhoon Longwang in 2005. According to the percentages of the river network where flooding occurred, the threshold conditions for flood severity were estimated in two scenarios: with and without working pumps. In Fuzhou City, working pumps efficiently reduce flood risk from precipitation within a 20-yr RP. However, the pumps may not work efficiently when rainfall exceeds a 100-yr RP because of the limited conveyance capacity of the river network. Joint risk probability was estimated through the optimal copula. The joint probability of rainfall and tidal level both exceeding their threshold values is very low, and the greatest threat in Fuzhou comes from heavy rainfall. However, the tidal level poses an extra risk of flood. Given that this extra risk is ignored in the design of flood defense in Fuzhou, flood frequency and severity may be higher than understood during design.

scholarly journals Joint impact of rainfall and tidal level on flood risk in a coastal city with a complex river network: a case study for Fuzhou city, China

2012 ◽  
Vol 9 (6) ◽  
pp. 7475-7505 ◽  
Author(s):  
J. J. Lian ◽  
K. Xu ◽  
C. Ma
Keyword(s):  
Flood Risk ◽  
Joint Probability ◽  
River System ◽  
Copula Function ◽  
River Network ◽  
Combined Effect ◽  
Tidal Level ◽  
Coastal City ◽  
Risk Degree

Abstract. Coastal cities are particularly vulnerable to flood under the combined effect of multivariable variables, such as heavy rainfall, high sea level and large waves. For better assessment and management of flood risk the combined effect and joint probability should be considered. This paper aims to study the joint impact of rainfall and tidal level on flood risk by estimating the combined risk degree of flood and the joint flood probability. The area of case study is a typical coastal city in China, which has a complex river system. The flood in this city is mainly caused by inundation of river system. In this paper, the combined risk degree of flood is assessed by analyzing the behavior of the complex river network of the city under the combined effect of rainfall and tidal level with diverse return periods. The hydraulic model of the complex drainage network is established using HEC-RAS and verified by comparing the simulation results with the observed data during Typhoon "Longwang". The joint distribution and combined risk probability of rainfall and tidal level are estimated using the optimal copula function. The work carried out in this paper would facilitate assessment of flood risk significantly, which can be referred for the similar cities.

Compound impact of rainfall, tidal level and storm surge on flood risk from tropical cyclones in the coastal area of shanghai

2020 ◽  
Author(s):  
Hanqing Xu
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
Storm Surge ◽  
Extreme Events ◽  
Joint Probability ◽  
Storm Surges ◽  
Heavy Precipitation ◽  
Tidal Level ◽  
Sea Levels ◽  
The Impact

<p>Catastrophic flooding resulting from extreme tropical cyclones has occurred more frequently and drawn great attention in recent years in China. Coastal cities are particularly vulnerable to flood under multivariable conditions, such as heavy precipitation, high sea levels, and storms surge. In coastal areas, floods caused by rainstorms and storm surges have been one of the most costly and devastating natural hazards in coastal regions. Extreme precipitation and storm tide are both inducing factors of flooding and therefore their joint probability would be critical to determine the flooding risk. Usually, extreme events such as tidal level, storm surges, precipitation occur jointly, leading to compound flood events with significantly higher hazards compared to the sum of the single extreme events. The purpose of this study is to improve our understanding of multiple drivers to compound flooding in shanghai. The Wind Enhance Scheme (WES) model characterized by Holland model is devised to generate wind "spiderweb" both for historical (1949-2018) and future (2031-2060, 2069-2098) tropical cyclones. The tidal level and storm surge model based on Delft3D-FLOW is employed with an unstructured grid to simulate the change of water level. For precipitation, maximum value between tropical cyclone events is selected. Following this, multivariate Copula model would be employed to compare the change of joint probability between tidal level, storm surge and heavy precipitation under climate change, taking into account sea-level rise and land subsidence. Finally, the impact of tropical cyclone on the joint risk of tidal, storm surge and heavy precipitation is investigated. </p>

scholarly journals CHALLENGES AND LESSONS LEARNED FROM COASTAL FLOOD RESILIENCE PLANNING IN VIRGINIA BEACH, VIRGINIA, USA

2018 ◽  
pp. 96
Author(s):  
Brian K. Batten ◽  
Gregory Johnson ◽  
Shanda Davenport
Keyword(s):  
New York ◽  
Planning Process ◽  
Flood Frequency ◽  
Lessons Learned ◽  
Sea Levels ◽  
Coastal Cities ◽  
Virginia Beach ◽  
Aging Infrastructure ◽  
The City

Many U.S. coastal cities face the challenge of increasing flood frequency and magnitude due to a combination of increasing sea levels, changing rainfall, and aging infrastructure. Recurrent flooding, sometimes referred to as “nuisance flooding”, can be symptomatic of such issues. Responding to such impacts can either be tacked in a piece-meal, reactive fashion, or proactively. A number of cities, such as New York (SIRR, 2013) and Boston (City of Boston, 2016) have undertaken or are in the process of planning efforts to recognize such issues and develop strategies to reduce impacts. The flood resilient planning process can take many forms, we shall provide a case-study example overview of a bottom-up, risk-informed effort by the City of Virginia Beach, VA.

Flood risk assessment for Ecuador 

2021 ◽  
Author(s):  
Melisa Mena-Benavides ◽  
Manuel Urrutia ◽  
Konstantin Scheffczyk ◽  
Angel A. Valdiviezo-Ajila ◽  
Jhoyzett Mendoza ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Risk Reduction ◽  
Flood Risk ◽  
Disaster Risk Reduction ◽  
Disaster Risk ◽  
Flood Frequency ◽  
Flood Risk Assessment ◽  
Essential Information ◽  
Synthetic Aperture Radar Data ◽  
Ecological Regions

<p>Understanding disaster risk is the first priority for action of the Sendai Framework for Disaster Risk Reduction (SFDRR) and is the essential information needed to guide disaster governance and achieve disaster risk reduction. Flooding is a natural hazard that causes the highest number of affected people due to disasters. In Ecuador from 1970 to 2019 flooding caused the highest amount of loss and damage to housing, and from 2016 to 2019 there were 1263 flood events reported. However, the differentiated impacts in flood exposed areas and what can be done to reduce risk and its impacts are still not well understood. In this research, we explored the different dimensions of flood risk, namely hazard, exposure, and vulnerability, and investigated the drivers of risk in different ecological regions of Ecuador. The assessment was conducted at the parish level, the smallest administrative scale, for three selected provinces of Bolivar, Los Ríos, and Napo, representing not only the country’s three main ecological regions but also commonly affected territories due to flooding. Using an automated flood detection procedure based on Sentinel-1 synthetic aperture radar data, flood hazard information was derived from flood frequency and flood depth for the years 2017, 2018, and 2019. The drivers of exposure and vulnerability were derived from scientific literature and further evaluated and complemented during a participatory workshop with over 50 local experts from the different regions. Centered on this exercise, an indicator library was created to inform the data selection from various sources and provides the basis for deriving a spatially explicit flood risk assessment using an indicator-based approach. Impact data are available to validate the risk assessment at the parish level and with this reveal key drivers of flood risk in different ecological regions of Ecuador. This information will provide the basis to derive targeted measures for disaster risk reduction.</p>

scholarly journals Oyster Hack

2018 ◽  
Author(s):  
Evelyn Tickle ◽  
Keyword(s):  
New York ◽  
Oyster Reefs ◽  
Sea Levels ◽  
National Geographic ◽  
Coastal Cities ◽  
Run Off ◽  
Functionally Impaired ◽  
The Usa ◽  
Rising Sea Levels ◽  
Engineered Systems

There is a state of emergency in the USA- catastrophic coastal erosion, rising sea levels at the rate of one-eighth of an inch per year and poor water quality. Oysters can help. Oysters filter the water, removing toxins. Oyster reefs are living infra-structures that protect coastlines from storms and tidal surges. But…many of the world’s existing oyster reefs are functionally impaired. The Chesapeake Bay is dying. Untreated chemical run-off and human waste is creating ‘Dead Zones’ where there is no oxygen to support marine life. Much of Hurricane Sandy’s damage to New York City could have been prevented. In the early 1800’s the Harbor was lined with living oyster reefs. Now, these are dead or dying, fragile and vulnerable. Miami is flooded on a regular basis reports Miami Herald. Our oyster reefs must be revived or rebuilt- they will help. Walls are not the answer. 14% of US coastal cities have massive sea-walls already. National Geographic reports that by 2100 one-third of our coastal cities will be protected by walls, that cost billions of dollars and will not provide protection from the most severe storms. I believe in the power of the oyster. The oyster is an engineer- its reefs and shells work together as a “system of systems” to protect our waters and coastlines. Without them we are sunk, literally, no matter how many engineered systems we humans try to substitute and pay billions of dollars to implement.

Novel use of climate model data for deriving future flood risk underwriting and risk selection data – A Hong Kong Case Study

2021 ◽  
Author(s):  
Rebecca Alexandre ◽  
Iain Willis
Keyword(s):  
Climate Change ◽  
Hong Kong ◽  
Flood Risk ◽  
Climate Model ◽  
Risk Mitigation ◽  
Flood Damage ◽  
Flood Frequency ◽  
Commercial Building ◽  
Model Data ◽  
Change Factors

<p>The re/insurance, banking and mortgage sectors play an essential role in facilitating economic stability. As climate change-related financial risks increase, there has long been a need for tools that contribute to the global industry’s current and future flood risk resiliency. Recognising this gap, JBA Risk Management has pioneered use of climate model data for rapidly deriving future flood risk metrics to support risk-reflective pricing strategies and mortgage analysis for Hong Kong.</p><p>JBA’s established method uses daily temporal resolution precipitation and surface air temperature Regional Climate Model (RCM) data from the Earth System Grid Federation’s CORDEX experiment. Historical and future period RCM data were processed for Representative Concentration Pathways (RCPs) 2.6 and 8.6, and time horizons 2046-2050 and 2070-2080 and used to develop fluvial and pluvial hydrological model change factors for Hong Kong. These change factors were applied to baseline fluvial and pluvial flood depths and extents, extracted from JBA’s high resolution 30m Hong Kong Flood Map. From these, potential changes in flood event frequency and severity for each RCP and time horizon combination were estimated.</p><p>The unique flood frequency and severity profiles for each flood type were then analysed with customised vulnerability functions, linking water depth to expected damage over time for residential and commercial building risks. This resulted in quantitative fluvial and pluvial flood risk metrics for Hong Kong.</p><p>Newly released, Hong Kong Climate Change Pricing Data is already in use by financial institutions. When combined with property total sum insured data, this dataset provides the annualised cost of flood damage for a range of future climate scenarios. For the first time, our industry has a tool to quantify baseline and future flood risk and set risk-reflective pricing for Hong Kong portfolios.</p><p>JBA’s method is adaptable for global use and underwriting tools are already available for the UK and Australia with the aim of improving future financial flood risk mitigation and management. This presentation will outline the method, provide a comparison of baseline and climate change flood impacts for Hong Kong and discuss the wider implications for our scientific and financial industries.</p>

METHODOLOGICAL CHALLENGES AND STRATEGIESTO INCORPORATE CLIMATE CHANGE INTO FLOOD RISK ANALYSIS OF SPANISH COASTAL CITIES

2019 ◽  
Author(s):  
MARÍA BERMÚDEZ ◽  
LUIS CEA ◽  
MIGUEL A. LOSADA ◽  
JERÓNIMO PUERTAS ◽  
MIGUEL ORTEGA- SÁNCHEZ
Keyword(s):  
Climate Change ◽  
Risk Analysis ◽  
Flood Risk ◽  
Coastal Cities ◽  
Methodological Challenges ◽  
Flood Risk Analysis
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