scholarly journals A participatory community case study of periurban coastal flood vulnerability in southern Ecuador

2019 ◽  
Author(s):  
Erica Tauzer ◽  
Mercy J. Borbor-Cordova ◽  
Jhoyzett Mendoza ◽  
Telmo de la Cuadra ◽  
Jorge Cunalata ◽  
...  
Keyword(s):  
Focus Groups ◽  
Adaptive Capacity ◽  
Flood Risk ◽  
El Nino ◽  
Flood Events ◽  
Community Members ◽  
Flood Vulnerability ◽  
Coastal City ◽  
El Niño Events

Background: Populations in coastal cities are exposed to increasing risk of flooding, resulting in rising damages to health and assets. Local adaptation measures, such as early warning systems for floods (EWSFs), are urgently needed to reduce the risk and impact of flood events. The aim of this study was to assess community perceptions and self-reported actions in response to flooding in a tropical coastal city to inform flood risk reduction policies and programs.Methods: This qualitative case study was conducted in flood-prone areas in Machala, Ecuador, a coastal city exposed to seasonal floods and extreme floods during El Niño events. Adult community members from three periurban sites were invited to participate. Focus groups discussions (11 focus groups in total) were held with community members (n=65 people) from September to November 2014 to assess perceptions of flood exposure, sensitivity, adaptive capacity, and current alert systems. Focus groups discussions were audio recorded, transcribed, and coded by topic; participatory maps were field validated, georeferenced, and digitized using GIS software. Results: Community members identified the presence of annual flooding during the rainy season, as well as greater than normal flood events (depths ranging from 0.5 to 3 meters), which recurred every 3-4 years in some communities. The deepest floods occurred during the 1982 and 1997/1998 El Niño events. Community members perceived that exposure to flooding depended on the rainfall coinciding with high ocean tides, and geographic proximity to blocked drainage areas, canals, and low local elevation. Participants reported that children were the most sensitive group due to increased susceptibility to skin infections and mosquito borne diseases (i.e., dengue fever). Other sensitive groups included the elderly, physically handicapped people, low-income families, and recent migrants. They identified persistent social-ecological vulnerabilities that increased flood risk and exposure in the urban periphery, such as inadequate access to garbage collection, homes settled in precarious low-lying geographies, economic barriers, lack of political access, and lack of social mobilization. In addition, communities expressed a lack of social capital (e.g. political voice), despite the existence of formalized community councils. Key neighborhood resources with respect to flooding included green areas, schools, nurseries, fire stations, health clinics, police stations, a retention wall (berm), and an emergency meeting place. Challenges for adaptive capacity existed primarily in actions related to the preparation and recovery stages of flooding. Despite the presence of an official flood warning system, community member relied on informal communication channels via social media. Conclusions: The flood vulnerability assessment framework and participatory research process utilized here can potentially inform studies in other flood-prone regions to guide the development of EWSFs and other climate change adaptation policies and actions.

scholarly journals Assessing changes on urban flood vulnerability through mapping land use from historical information

2015 ◽  
Vol 12 (6) ◽  
pp. 6151-6177 ◽  
Author(s):  
M. Boudou ◽  
B. Danière ◽  
M. Lang
Keyword(s):  
Land Use ◽  
Flood Risk ◽  
Local Scale ◽  
Flood Events ◽  
Historical Sources ◽  
Flood Vulnerability ◽  
Urban Flood ◽  
Xxth Century ◽  
Historical Information ◽  
Significant Events

Abstract. This paper presents a diachronic appraisal of flood vulnerability of two French cities, respectively Besançon and Moissac, which have been largely impacted by two ancient floods in January 1910 and March 1930. Both flood events figured among the most significant events recorded in France during the XXth century. An analysis of historical sources allows the mapping of land use and occupation within the flood extent of the two historical floods, both in past and present contexts. It gives an insight of the complexity of flood risk evolution, at a local scale.

scholarly journals Estimating the Probability of Compound Floods in Estuarine Regions

2020 ◽  
Author(s):  
Wenyan Wu ◽  
Seth Westra ◽  
Michael Leonard
Keyword(s):  
Frequency Analysis ◽  
Flood Risk ◽  
Data Availability ◽  
Flood Frequency Analysis ◽  
Accurate Estimation ◽  
Flood Events ◽  
Advantages And Disadvantages ◽  
Comparative Review ◽  
Flood Probability

Abstract. The quantification of flood risk in estuarine regions relies on accurate estimation of flood probability, which is often challenging due to the rareness of flood events and their multi-causal (or compound) nature. Failure to consider the compounding nature of estuarine floods can lead to significant underestimation of flood risk in these regions. This study provides a comparative review of alternative approaches for estuarine flood estimation; namely, traditional univariate flood frequency analysis applied to both observed historical data and simulated data, and multivariate frequency analysis applied to flood events. Three specific implementations of the above approaches are evaluated on a case study – the estuarine portion of Swan River in Western Australia, highlighting the advantages and disadvantages of each approach. The theoretical understanding of the three approaches, combined with findings from the case study, enable generation of guidance on method selection for estuarine flood probability estimation, recognising issues such as data availability, complexity of the application/analysis process, location of interest within the estuarine region, computational demands and whether or not future conditions need to be assessed.

scholarly journals Estimating the probability of compound floods in estuarine regions

2021 ◽  
Vol 25 (5) ◽  
pp. 2821-2841
Author(s):  
Wenyan Wu ◽  
Seth Westra ◽  
Michael Leonard
Keyword(s):  
Frequency Analysis ◽  
Flood Risk ◽  
Data Availability ◽  
Flood Frequency Analysis ◽  
Accurate Estimation ◽  
Flood Events ◽  
Advantages And Disadvantages ◽  
Comparative Review ◽  
Flood Probability

Abstract. The quantification of flood risk in estuarine regions relies on accurate estimation of flood probability, which is often challenging due to the rareness of hazardous flood events and their multi-causal (or “compound”) nature. Failure to consider the compounding nature of estuarine floods can lead to significant underestimation of flood risk in these regions. This study provides a comparative review of alternative approaches for estuarine flood estimation – namely, traditional univariate flood frequency analysis applied to both observed historical data and simulated data, as well as multivariate frequency analysis applied to flood events. Three specific implementations of the above approaches are evaluated on a case study – the estuarine portion of Swan River in Western Australia – highlighting the advantages and disadvantages of each approach. The theoretical understanding of the three approaches, combined with findings from the case study, enable the generation of guidance on method selection for estuarine flood probability estimation, recognizing issues such as data availability, the complexity of the application/analysis process, the location of interest within the estuarine region, the computational demands, and whether or not future conditions need to be assessed.

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.

scholarly journals Flood vulnerability reduction. Case study: Tazlău river basin, downstream of its confluence with Tazlău Sărat

2021 ◽  
Vol 15 (2) ◽  
pp. 189-198
Author(s):  
Alina Tirnovan ◽  
Ovidiu Covaci ◽  
Marius Robert Gazda ◽  
Narcis Barsan ◽  
Andrei Enea
Keyword(s):  
River Basin ◽  
Flood Risk ◽  
Left Bank ◽  
The European Union ◽  
Risk Area ◽  
Flood Vulnerability ◽  
Management Plans ◽  
Reduction Case ◽  
Flood Risk Management Plans

The issue of water management as well as its impact on the community has been both a challenge and a concern of the European Union, which lead to adopting the Directive 2007/60/EC with the purpose of establishing a framework for the assessment and management of flood risks, by which the member states had to identify the areas for which they conclude that potential significant flood risk exist or likely to occur and to develop flood risk management plans and measures to reduce the consequences of flooding. In this respect, the Siret Water Basin Administration has declared the area of the Tazlău river, as a significant flood risk area (A.P.F.S.R.) (*** A.B.A Siret). The Tazlău River is a left-bank tributary to the Trotuș River, passing through the ten communes and partially through the outside the built-up areas of Onești city. Recent studies have shown the benefits of reservoirs and floodplains, as these provide the most effective way to buffer the effect of floods by slowing and spreading the discharge of a river (Băloi, 1980). By restoring and improving an existing lateral floodplain in the Tazlău River basin, in order to store part of the floodwaters that cause significant adverse consequences, will reduce the flood vulnerability of its crossings.

Better use and management of levees: reducing flood risk in a changing climate

2015 ◽  
Vol 23 (2) ◽  
pp. 240-255 ◽  
Author(s):  
Caroline Wenger
Keyword(s):  
Flood Risk ◽  
Flood Risk Management ◽  
Flood Mitigation ◽  
Flood Events ◽  
Institutional Barriers ◽  
Detailed Review ◽  
Adverse Impacts ◽  
The Usa ◽  
Adaptive Approaches

Many nations rely on dykes and levees to mitigate flood risk. However, a myriad of problems has prompted views that levees are ultimately maladaptive and should be used as a measure of last resort. This leads to questions not only about the place of levees in future flood risk management, but also whether anything can be done to reduce their impacts. A detailed review of flood events from Australia, China, the Netherlands, and the USA was used to develop a case study for each country. Case studies present existing levee problems, future flood threats, and national strategies to address them. These were used as a basis to analyse the transferability of adaptive flood approaches. While many countries are attempting to restore floodplain storage, thereby reducing their reliance on levees, others are increasing their investment in levee construction. This review explores factors that affect the transferability of adaptive approaches, including issues, such as problem recognition, affordability, and program delivery. It was found that countries vary in their ability to recognise levee problems, and the level at which decisions are made influences the likelihood of adaptive solutions being adopted. Analysis suggests that federal systems face particular challenges and their capacity to adopt adaptive approaches may be impaired if institutional barriers are not addressed. Regardless of the overall approach to manage flood risk, the experiences of all case study countries offer some broadly applicable lessons for improving the use and management of levees, reducing their adverse impacts, and improving the integration of natural flood mitigation.

scholarly journals Assessing changes in urban flood vulnerability through mapping land use from historical information

2016 ◽  
Vol 20 (1) ◽  
pp. 161-173 ◽  
Author(s):  
M. Boudou ◽  
B. Danière ◽  
M. Lang
Keyword(s):  
Land Use ◽  
20Th Century ◽  
Flood Risk ◽  
Temporal Evolution ◽  
Local Scale ◽  
Flood Events ◽  
Historical Sources ◽  
Flood Vulnerability ◽  
Urban Flood ◽  
Significant Events

Abstract. This paper presents an appraisal of the temporal evolution of flood vulnerability of two French cities, Besançon and Moissac, which were largely impacted by floods in January 1910 and March 1930, respectively. Both flood events figure among the most significant events recorded in France during the 20th century, in terms of certain parameters such as the intensity and severity of the flood and spatial extension of the damage. An analysis of historical sources allows the mapping of land use and occupation within the areas affected by the two floods, both in past and present contexts, providing an insight of the complexity of flood risk evolution at a local scale.

Unravelling socio-hydrological processes behind cascading drought-to-flood disasters

2021 ◽  
Author(s):  
Anne Van Loon ◽  
Alessia Matanó ◽  
Giuliano di Baldassarre ◽  
Rosie Day ◽  
Margaret Garcia ◽  
...  
Keyword(s):  
System Dynamics ◽  
Case Studies ◽  
Flood Risk ◽  
Mental Simulation ◽  
Climate Projections ◽  
Flood Events ◽  
Millennium Drought ◽  
The World ◽  
Flood Disasters

<p>Future climate projections show a strengthening of the hydrological cycle with more droughts and floods expected in many regions of the world. This means a higher likelihood of cascading drought-to-flood disasters such as the Millennium Drought – Brisbane flooding in Australia or the California drought – Oroville spillway collapse in the US. Droughts allow ample time for impacts and adaptation, which influence hazard, exposure, and vulnerability of a subsequent flood. When we treat the flood risk as independent from the drought this might lead to large underestimations of future risk.</p><p>Here, we present the PerfectSTORM project (‘STOrylines of futuRe extreMes’). In this project we will study drought-to-flood events to provide the understanding needed to prevent major disasters in the future. We will use a mixed-methods approach based on a combination of qualitative and quantitative storylines of past and future drought-to-flood risk in case studies and extrapolation of this rich case study information to the global scale. Qualitative storylines will be collected with narrative interviews and mental simulation workshops and will be analysed to develop timelines and causal loop diagrams. Quantitative storylines will be developed from timeseries of hydrological and social data that will be analysed to distinguish interrelated drivers and modelled with system dynamics modelling. These storylines will then be combined in an iterative way using innovative data visualisation as a basis for co-creating management solutions.</p><p>To generalise our case study understanding, a range of global datasets will be analysed to find global types and hotspots of drought-to-flood events. This information will be combined with the system dynamics model developed in the case studies and a global multi-dimensional possibility space will be developed. This will allow us to explore positive pathways for future management of drought-to-flood events in different parts of the world. The PerfectSTORM project will provide in-depth understanding of the hydrosocial feedbacks and dynamic vulnerability of cascading hazards.</p>

Hydro-BID case study No. 3: Impact of El Niño Events on Sediment Loading in the Chancay-Lambayeque Basin, Peru

2016 ◽  
Author(s):  
Jorge Escurra ◽  
Fekadu Moreda ◽  
Eugene Brantly ◽  
Pedro Coli Valdes Daussa
Keyword(s):  
El Niño ◽  
El Nino ◽  
Sediment Loading ◽  
El Niño Events ◽  
El Nino Events
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