scholarly journals A flood risk framework capturing the seasonality of and dependence between rainfall and sea levels – an application to Ho Chi Minh City, Vietnam

2022 ◽  
Author(s):  
A. Couasnon ◽  
P. Scussolini ◽  
T. V. T. Tran ◽  
D. Eilander ◽  
S. Muis ◽  
...  
Keyword(s):  
Flood Risk ◽  
Ho Chi Minh City ◽  
Sea Levels ◽  
Risk Framework

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 Assessment of the effectiveness of flood adaptation strategies for HCMC

2014 ◽  
Vol 14 (6) ◽  
pp. 1441-1457 ◽  
Author(s):  
R. Lasage ◽  
T. I. E. Veldkamp ◽  
H. de Moel ◽  
T. C. Van ◽  
H. L. Phi ◽  
...  
Keyword(s):  
Sea Level ◽  
Flood Risk ◽  
Net Present Value ◽  
Adaptation Strategies ◽  
Ho Chi Minh City ◽  
Cost Ratio ◽  
Present Value ◽  
Benefit Cost Ratio ◽  
Coastal Cities ◽  
Benefit Cost

Abstract. Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, Asian cities in particular are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reduction measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea-level rise and socio-economic developments on flood risk for the flood-prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry- and wet proofing of buildings and elevating roads and buildings). A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage–damage curves for residential buildings. The model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in expected annual damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea-level scenarios and land-use scenarios. Together with information on costs of these strategies, we calculated the benefit–cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5% and 5%. The results of this modelling study indicate that the current flood risk in District 4 is USD 0.31 million per year, increasing up to USD 0.78 million per year in 2100. The net present value and benefit–cost ratios using a discount rate of 5 % range from USD −107 to −1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5% leads to an increase in both net present value and benefit–cost ratio. The adaptation strategies wet-proofing and dry-proofing generate the best results using these economic indicators. The information on different strategies will be used by the government of Ho Chi Minh City to determine a new flood protection strategy. Future research should focus on gathering empirical data right after a flood on the occurring damage, as this appears to be the most uncertain factor in the risk assessment.

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 Future flood risk exacerbated by the dynamic impacts of sea level rise

2020 ◽  
Author(s):  
Matthew Bilskie ◽  
Diana Del Angel ◽  
David Yoskowitz ◽  
Scott Hagen
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Flood Risk ◽  
Residential Buildings ◽  
Flood Damage ◽  
Coastal Communities ◽  
Modeling Framework ◽  
Sea Levels ◽  
Coastal Landscapes ◽  
Block Level

Abstract A growing concern of coastal communities is an increase in flood risk and non-monetary consequences as a result of climate-induced impacts such as sea level rise (SLR). While previous studies have outlined the importance of quantifying future flood risk, most have focused on broad aggregations of monetary loss using bathtub SLR-type models. Here we quantify, for the first time at the multi-state scale, actual impacts to coastal communities at the census block level using a dynamic, high-resolution, biogeophysical modeling framework that accounts for future sea-levels and coastal landscapes. We demonstrate that future SLR can increase the number of damaged residential buildings by 600%, the population of displaced people by 500% and the need for shelter assistance of up to 460% from present-day conditions. An exponential increase in flood damage associated with increasing sea level deems it essential for stakeholders to plan for plausible future conditions rather than the current reality.

Multi-Criteria Decision Analysis of Coastal Inundation at Regional scale

2021 ◽  
Author(s):  
Vinay Shivamurthy ◽  
Bharath Aithal
Keyword(s):  
High Risk ◽  
Decision Analysis ◽  
Sea Level Rise ◽  
Sea Level ◽  
Natural Hazards ◽  
Flood Risk ◽  
Sea Levels ◽  
Risk Levels ◽  
Multi Criteria Decision Analysis ◽  
Rising Sea Levels

<p>Coastal flooding are natural processes that are both i) essential (providing nutrients to the coastal vegetation, habitats) and ii) hazardous (negatively impact human activities, livelihood, assets, livestock and so on). Climate changes have induced higher frequency of floods, rising sea levels, high amplitude tides and other climatic extremes at regional to global scales. The increasing intensity, duration of floods is proportionately increasing the risks associated with coastal human habitations. The regional risks are defined based on the physical, demographic, socio-economic vulnerability of the habitants. Sea level rise would further enhance the coastal inundations permanently breaching these productive, densely populated regions. This necessitates the need for spatially assessing the relative hazard, vulnerability and risks at regional scales to reduce/mitigate risks.</p><p>Indian subcontinent supports the second largest global population, with numerous megacities, towns and villages along the coast and mainland. This study's main objective is to quantify the risk associated with inundations caused by rising sea levels, tidal surge at the regional level. As a case study, Sagar Island located in the verge of Sundarbans, south of West Bengal is considered. Flood risk assessment in the island has been carried out using Multi-Criteria Decision Analysis (MCDA) framework based on 23 spatial parameters.</p><p>Results indicate, within a century (1922 – 2020), the island has lost most of its natural vegetation (mangroves - Sundarbans) (47% to 3%), with increasing cultivated (agriculture, horticulture) spaces (77.4 %) and built-up environs (8.2%). Sea level rise varies from 4.4 mm/year (South) to 5.25 mm/year (North) and in the last century has breached over 2824 hectares of mainland. The study's findings reveal 19.8% of horticulture and 33.3% of agriculture assets are highly exposed to natural hazards. 1.34% population are at relatively very high-risk levels, 17.81% at high-risk levels. The study's findings reveal the variable importance of socio-economic, demographic, topographic and proximity to public service, in defining the flood vulnerability and risk towards the habitants. The approach and findings of paves the way for planning authorities to prioritise risk mitigation strategies that are region-specific to reduce the impact of inundation due to natural hazards</p><p><em>Keywords: Sea level rise, Flood risk, MCDA, Vulnerability, flood hazard</em></p>

scholarly journals BRICK v0.1, a simple, accessible, and transparent model framework for climate and regional sea-level projections

2017 ◽  
Author(s):  
Tony E. Wong ◽  
Alexander Bakker ◽  
Kelsey Ruckert ◽  
Patrick Applegate ◽  
Aimée Slangen ◽  
...  
Keyword(s):  
Simple Model ◽  
Sea Level ◽  
Flood Risk ◽  
Building Blocks ◽  
Computationally Efficient ◽  
Model Framework ◽  
Sea Levels ◽  
Model Components ◽  
High Degree ◽  
Simple Models

Abstract. Simple models can play pivotal roles in the quantification and framing of uncertainties surrounding climate change and sea-level rise. They are computationally efficient, transparent, and easier to reproduce. These qualities make simple models useful for uncertainty quantification and risk characterization. Simple model codes are increasingly distributed as open source, as well as actively shared and guided. Alas, computer codes used in the geosciences can often be hard to access, run, modify (e.g., with regards to assumptions and model components), and review. Here, we introduce a simple model framework for projections of global mean temperatures as well as regional sea levels and coastal flood risk (BRICK: Building blocks for Relevant Ice and Climate Knowledge). The BRICK model framework is written in R and Fortran and aims to help mitigate these issues, while maintaining a high degree of computational efficiency. We demonstrate the flexibility of this framework through simple model intercomparison experiments. Furthermore, we demonstrate that BRICK is suitable for risk assessment applications by using a didactic example in local flood risk management.

scholarly journals Rapidly changing seasonal sea levels increase flood risk

Eos ◽  
2014 ◽  
Vol 95 (18) ◽  
pp. 156-156
Author(s):  
JoAnna Wendel
Keyword(s):  
Flood Risk ◽  
Sea Levels

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.

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