Participatory modelling of vulnerability and adaptive capacity in flood risk management

Being part of the EU-project NeWater on adaptive water resources management, the Ukrainian Tisa river basin is presented as an example for a participatory study dealing with flood risk, vulnerability and adaptive capacity. The Tisa valley is regularly and increasingly faced with hazardous floods at very limited local budgets and high poverty rates. In order to make flood risk management more resilient and better adapted to climate change, scientists and stakeholders applied a set of qualitative and quantitative modelling approaches to characterise prevailing flood risk management, to discover respective vulnerabilities and to identify barriers and options of adaptive capacity. The former were found in the defensive mentality paradigm and the inert and hierarchical structure of present institutions, the latter in, firstly, an enormous potential to link the knowledge of different stakeholders in the region, secondly, a better integration of the individual flood preparedness of households and thirdly, the active involvement of the Church as institution in local flood risk management.     

Urban flood vulnerability assessments: the case of Dire Dawa city,Ethiopia

Dire Dawa city is identified as one of the most flood-affected cities in Ethiopia. Classifying village-level flood vulnerability using flood indicators is a new approach to Dire Dawa city. Analysis of different flood vulnerability factors underpins sustainable flood risk management and the application of Flood Vulnerability Index (FVI) approach is the hub of this study. Relevant data were collected from 110 households sampled from purposely selected 10 villages found in Dire Dawa city. The flood vulnerability index was used to compare, classify and rank villages in terms of their flood vulnerability levels. For this purpose, 24 sets of indicators which are strongly affecting the levels of flood vulnerability were assessed from social, economic and physical perspectives. The FVI of each village was computed with unequal method of weighting indicators. The findings of the study revealed that Dire Dawa city villages were experiencing varying levels of flood vulnerability. Accordingly, villages 05, 06, 07 and 09 were identified with high flood vulnerability level while villages 03, 04 and 08 and villages 01, 02 and extension village were identified with medium and low level of vulnerability, respectively. Interestingly, the findings of the study confirmed that social factors contributed much for flood vulnerability in Dire Dawa city. Hence, future urban flood risk planning and management endeavors in the city of Dire Dawa must be underpinned by proper utilization of the flood vulnerability map developed addressing social vulnerability component through both structural and non-structural urban flood risk management measures.

     

Integration of earth observation and census data for mapping a multi-temporal flood vulnerability index: a case study on Northeast Italy

Climate sciences foresee a future where extreme weather events could happen with increased frequency and strength, which would in turn increase risks of floods (i.e. the main source of losses in the world). The Mediterranean basin is considered a hot spot in terms of climate vulnerability and risk. The expected impacts of those events are exacerbated by land-use change and, in particular, by urban growth which increases soil sealing and, hence, water runoff. The ultimate consequence would be an increase of fatalities and injuries, but also of economic losses in urban areas, commercial and productive sites, infrastructures and agriculture. Flood damages have different magnitudes depending on the economic value of the exposed assets and on level of physical contact with the hazard. This work aims at proposing a methodology, easily customizable by experts’ elicitation, able to quantify and map the social component of vulnerability through the integration of earth observation (EO) and census data with the aim of allowing for a multi-temporal spatial assessment. Firstly, data on employment, properties and education are used for assessing the adaptive capacity of the society to increase resilience to adverse events, whereas, secondly, coping capacity, i.e. the capacities to deal with events during their manifestation, is mapped by aggregating demographic and socio-economic data, urban growth analysis and memory on past events. Thirdly, the physical dimension of exposed assets (susceptibility) is assessed by combining building properties acquired by census data and land-surface characteristics derived from EO data. Finally, the three components (i.e. adaptive and coping capacity and susceptibility) are aggregated for calculating the dynamic flood vulnerability index (FVI). The approach has been applied to Northeast Italy, a region frequently hit by floods, which has experienced a significant urban and economic development in the past decades, thus making the dynamic study of FVI particularly relevant. The analysis has been carried out from 1991 to 2016 at a 5-year steps, showing how the integration of different data sources allows to produce a dynamic assessment of vulnerability, which can be very relevant for planning in support of climate change adaptation and disaster risk reduction.

     

A simplified approach for flood vulnerability assessment of historic sites

In the last decades, floods have increased in frequency all over the world due to diverse phenomena such as climate change, extended urbanization, land use, etc. Their social, cultural, economic and environmental impacts have also grown significantly, highlighting the need for the development of further studies and improved methods to manage and mitigate flood risk, mainly in urban areas. Historic sites need particular attention in this field, not only because the high and irreplaceable cultural value of these areas, but also taking into account that the constructive typologies that they host are particularly vulnerable to natural hazards. In consequence of that, the analysis of the phenomena, the evaluation of their consequences and the adoption of adequate mitigation and preparedness measures are presently a fundamental societal challenge. Having this in mind, the present paper aims at proposing an innovative methodology focused on the assessment of flood vulnerability in historic sites through the evaluation of a set of exposure and sensitivity indicators. From the analysis of these indicators, it is possible to obtain a Flood Vulnerability Index capable of measuring the spread of flood vulnerability over an extended area. The historic centre of Guimarães, in Portugal, declared by UNESCO as a World Heritage Site in 2001, is used here as a pilot case study to apply and discusses the preliminary version of the approach. Although some improvements are still needed, this approach can be already used to provides preliminary vulnerability scenarios and to point the way to the definition of more efficient and customized strategies for managing and mitigating flood risk in historic sites. Moreover, with further improvements and calibrations resorting to larger and more diverse data, it will be possible to reduce some of the uncertainties currently involved in the assessment process and to make its application wider and more robust.

     

A multicriteria approach for flood risk mapping exemplified at the Mulde river,Germany

In this paper we develop a GIS-based multicriteria flood risk assessment and mapping approach. This approach includes flood risks which are not measured in monetary terms; it shows the spatial distribution of multiple risks, and it is able to deal with uncertainties in criteria values and to show their influence on the overall flood risk assessment. Additionally, the approach can be used to show the spatial allocation of the flood effects if risk reduction measures are implemented. The approach is applied to a pilot study for the River Mulde in Saxony, Germany, heavily affected by the hazardous flood in 2002. Therefore, a GIS database of economic, social and environmental risk criteria was created. Two different multicriteria decision rules, a disjunctive and an additive weighting approach, are utilised for an overall flood risk assessment in the area. For implementation, a software tool (FloodCalc) was developed supporting both, the risk calculation of the single criteria as well as the multicriteria analysis.

An innovative micro-scale approach for vulnerability and flood risk assessment with the application to property-level protection adoptions

Economic damage assessment for flood risk estimation is established in many countries, but attentions have been focused on macro- or meso-scale approaches and less on micro-scale approaches. Whilst the macro- or meso-scale approaches of flood damage assessment are suitable for regional- or national-oriented studies, micro-scale approaches are more suitable for cost–benefit analysis of engineered protection measures. Furthermore, there remains lack of systematic and automated approaches to estimate economic flood damage for multiple flood scenarios for the purpose of flood risk assessment. Studies on flood risk have also been driven by the assumption of stationary characteristic of flood hazard, hence the stationary-oriented vulnerability assessment. This study proposes a novel approach to assess vulnerability and flood risk and accounts for adaptability of the approach to nonstationary conditions of flood hazard. The approach is innovative in which an automated concurrent estimation of economic flood damage for a range of flood events on the basis of a micro-scale flood risk assessment is made possible. It accounts for the heterogeneous distribution of residential buildings of a community exposed to flood hazard. The feasibility of the methodology was tested using real historical flow records and spatial information of Teddington, London. Vulnerability curves and residual risk associated with a number of alternative extents of property-level protection adoptions are estimated by the application of the proposed methodology. It is found that the methodology has the capacity to provide valuable information on vulnerability and flood risk that can be integrated in a practical decision-making process for a reliable cost–benefit analysis of flood risk reduction options.     

Modelling the flood vulnerability of deltaic Kuching City,Malaysia

The main objective of this writing is to present a practical way to envisage the flood vulnerability in deltaic region, particularly on the concern of sea level rise. Kuching city of Malaysia is established on banks of Sarawak River, 30 km from the sea. Therefore, it is subjected to fluvial and tidal floods. Kuching Bay experiences the highest King Tides in Southeast Asia region. These tide magnitudes could be a glimpse of future sea level rise. By means of modelling these tides, it provides an understanding and preparation for the impacts of sea level rise on the flood mitigation infrastructures and the city itself. The modelling efforts had created an illustration that a 10% rise in tide levels would result in increase of flooding areas up to 6% relative to existing tide levels.     

Alternative water management options to reduce vulnerability for climate change in the Netherlands

Urbanization, land subsidence and sea level rise will increase vulnerability of the urbanized low-lying areas in the western part of the Netherlands. In this article possibilities are explored to reduce vulnerability of these areas by implementing alternative water management options. Two main water management fields are distinguished, water supply and flood control. A four-component vulnerability framework is presented that includes threshold capacity, coping capacity, recovery capacity, and adaptive capacity. By using the vulnerability framework it is shown that current water supply and flood control strategies in the Netherlands focus on increasing threshold capacity by constructing higher and stronger dikes, improved water storage and delivery infrastructure. A complete vulnerability decreasing strategy requires measures that include all four capacities. Flood damage reduction, backup water supply systems and emergency plans are measures that can contribute to increasing coping capacity. Recovery capacity can be increased by multi-source water supply, insurance, or establishing disaster funds. Adaptive capacity can be developed by starting experiments with new modes of water supply and urbanization. Including all four components of the vulnerability framework enables better understanding of water and climate related vulnerability of urban areas and enables developing more complete water management strategies to reduce vulnerability.     

Integrated methodology for flood risk assessment and application in urban communities of Pakistan

Flood disasters and its consequent damages are on the rise globally. Pakistan has been experiencing an increase in flood frequency and severity along with resultant damages in the past. In addition to the regular practices of loss and damage estimation, current focus is on risk assessment of hazard-prone communities. Risk measurement is complex as scholars engaged in disaster science and management use different quantitative models with diverse interpretations. This study tries to provide clarity in conceptualizing disaster risk and proposes a risk assessment methodology with constituent components such as hazard, vulnerability (exposure and sensitivity) and coping/adaptive capacity. Three communities from different urban centers in Pakistan have been selected based on high flood frequency and intensity. A primary survey was conducted in selected urban communities to capture data on a number of variables relating to flood hazard, vulnerability and capacity to compute flood risk index. Households were categorized into different risk levels, such as can manage risk, can survive and cope, and cannot cope. It was found that risk levels varied significantly across the households of the three communities. Metropolitan city was found to be highly vulnerable as compared to smaller cities due to weak capacity. Households living in medium town had devised coping mechanisms to manage risk. The proposed methodology is tested and found operational for risk assessment of flood-prone areas and communities irrespective of locations and countries.     

Preliminary flood risk assessment: the case of Athens

Flood mapping, especially in urban areas, is a demanding task requiring substantial (and usually unavailable) data. However, with the recent introduction of the EU Floods Directive (2007/60/EC), the need for reliable, but cost effective, risk mapping at the regional scale is rising in the policy agenda. Methods are therefore required to allow for efficiently undertaking what the Directive terms “preliminary flood risk assessment,” in other words a screening of areas that could potentially be at risk of flooding and that consequently merit more detailed attention and analysis. Such methods cannot rely on modeling, as this would require more data and effort that is reasonable for this high-level, screening phase. This is especially true in urban areas, where modeling requires knowledge of the detailed urban terrain, the drainage networks, and their interactions. A GIS-based multicriteria flood risk assessment methodology was therefore developed and applied for the mapping of flood risk in urban areas. This approach quantifies the spatial distribution of flood risk and is able to deal with uncertainties in criteria values and to examine their influence on the overall flood risk assessment. It can further assess the spatially variable reliability of the resulting maps on the basis of the choice of method used to develop the maps. The approach is applied to the Greater Athens area and validated for its central and most urban part. A GIS database of economic, social, and environmental criteria contributing to flood risk was created. Three different multicriteria decision rules (Analytical Hierarchy Process, Weighted Linear Combination and Ordered Weighting Averaging) were applied, to produce the overall flood risk map of the area. To implement this methodology, the IDRISI Andes GIS software was customized and used. It is concluded that the results of the analysis are a reasonable representation of actual flood risk, on the basis of their comparison with historical flood events.     

Social vulnerability and seismic risk perception. Case study: the historic center of the Bucharest Municipality/Romania

Social vulnerability is as much a part of risk as building damage, hazard magnitude, and economic loss. Social vulnerability refers to the capacity of a human community exposed during the impact of a natural hazard event (in this case, an earthquake) to resist, cope with, and recover from that impact. In the perspective of the 3rd millennium, we come to understand that the most efficient and accessible way to reduce the pressure of natural risks is to reduce the vulnerability level of the human communities exposed to that certain hazard. This study aims to test, in an exposed and vulnerable area, the relationship between social vulnerability and the perception of the seismic risk. The research focuses only on the first level of social vulnerability, defined as the ability of an individual within a household to recover from a natural hazard impact (Dwyer et al. 2004). A prevailing assumption was that social vulnerability influences the level of perception of the seismic risk, in an exposed, vulnerable area. To this end, two samples were used, different under the aspect of social vulnerability, in the context of the same residential area. Social vulnerability was computed as a normalized composed index that includes the poverty ratio and the demographic vulnerability ratio (depending on the age, gender, and education level indicators). The statistical processing has indicated a significant difference in the high perception level for the two samples that were compared, in the sense that in the context of an increased level of social vulnerability, people generally better acknowledge the seismic risk.

Waterlogging and flood hazards vulnerability and risk assessment in Indo Gangetic plain

The recurrent flooding during monsoon and subsequent waterlogging in the northern Bihar plains and the magnitude of losses due to these hazards indicate the continuing vulnerability of the region to flood and waterlogging. Management of floods and waterlogging hazards in highly flood-prone regions of India, including Bihar state has been largely response oriented with little or no attention to mitigation and preparedness. This paper presents a method for spatial, Geographic Information Systems-based assessment of flood and waterlogging vulnerability and risk in northern Bihar plains. Multitemporal satellite data was used to evaluate the area statistics and dynamics of waterlogging over the period from 1975 to 2008. The flood proneness is evaluated at district level with reference to flood inundation during a period from 1998 to 2008. Census data were used to examine the socio-economic characteristics of the region through computation of population density, cultivators, agricultural labourers, sex ratio, children in age group 0–6 years and literates. The geohazard map derived by combining area prone to waterlogging and flood inundation was multiplied with socio-economic vulnerability map to derive the flood-waterlogging risk map of the region. The result shows that flood and water-logging pose highest risk to the central districts in the northern Bihar plains with 50.95% of the total area under high and very high risk.     

Use of LSPIV in assessing urban flash flood vulnerability

The probability of the occurrence of urban flash floods has increased appreciably in recent years. Scientists have published various articles related to the estimation of the vulnerability of people and vehicles in urban areas resulting from flash floods. However, most published works are based on research performed using numerical models and laboratory experiments. This paper presents a novel approach that combines the implementation of image velocimetry technique (large-scale particle image velocimetry—LSPIV) using a flash flood video recorded by the public locally and the estimation of the vulnerability of people and vehicles to high water velocities in urban areas. A numerical one‐dimensional hydrodynamic model has also been used in this approach for water velocity characterization. The results presented in this paper correspond to a flash flood resulting on November 29, 2012, in the city of Asunción in Paraguay. During this flash flood, people and vehicles were observed being carried away because of high water velocities. Various sequences of the recorded flash flood video were characterized using LSPIV. The results obtained in this work validate the existing vulnerability criterion based on the effect of the flash flood and resulting high water velocities on people and vehicles.     

Assessment of flood hazard,vulnerability and risk of mid-eastern Dhaka using DEM and 1D hydrodynamic model

Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map for mid-eastern Dhaka (37.16 km²) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography Mission and the hydrologic field-observed data for 32 years (1972–2004). As the topography of the area has been considerably changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future.     

Flood vulnerability assessment of residential buildings by explicit damage process modelling

Natural Hazards - The present paper introduces a vulnerability modelling approach for residential buildings in flood. The modelling approach explicitly considers relevant damage processes, i.e....     

Perception of flood risk in Danube Delta,Romania

For exposed and vulnerable communities, the perception of natural risk is an essential link in the analysis of man–environment coping relationship and also an important parameter in the quantification of complex vulnerability as a central predictive variable in the risk equation. The topic of flood risk in related perception is of considerable interest, as some recently published papers have proven (Messner and Meyer 2005, 2006; Raaijmakers et al. 2008). The aim of the current study is to reveal the conscious and unconscious attitudes towards the flood risk for the inhabitants of the Danube Delta/Romania. These attitudes, defined by different degrees of psychological vulnerability, represent the background for a series of psycho-behavioural patterns that generate certain adjustment mechanisms and strategies. Application of a specially designed questionnaire and the statistical analysis of the results revealed two psychological factors as essential in establishing the psychosocial vulnerability degree of the interviewed subjects: (i) an internal control factor and (ii) an external control factor. The persons characterized by inner control have a significantly reduced general anxiety level in comparison to individuals with the control factor placed externally. As confidence diminishes, it increases the tendency of the individual to rely on the external factors for support and security. The lack of resources (indicating lower resilience) and mistrust in the support given emphasizes non-adaptive behaviours.

Vulnerability assessment of an urban flood in Nigeria: Abeokuta flood 2007

The paper presents the result of a vulnerability assessment of urban dwellers to a major flood hazard in Abeokuta, southwestern Nigeria in July 2007. This was achieved by means of questionnaire survey administered to 248 flood area residents. Flood vulnerability was assessed by examining exposure, susceptibility, and coping indicators in the study area. Findings of the study show that although about 50% of respondents had experienced floods, in Abeokuta or elsewhere in the past, majority (66%) did not anticipate a flood event of such magnitude to occur despite its location on a flood plain and, therefore, were unprepared for such hazard. Pre-warning of the flood event was generally lacking among flood area residents as only 8% of respondents indicated pre-warning, which was based on personal observations. Response to the flood hazard was mainly reactive for both private and public agents as flood risk reduction measures were not in place.     

A flood vulnerability index for coastal cities and its use in assessing climate change impacts

Worldwide, there is a need to enhance our understanding of vulnerability and to develop methodologies and tools to assess vulnerability. One of the most important goals of assessing coastal flood vulnerability, in particular, is to create a readily understandable link between the theoretical concepts of flood vulnerability and the day-to-day decision-making process and to encapsulate this link in an easily accessible tool. This article focuses on developing a Coastal City Flood Vulnerability Index (CCFVI) based on exposure, susceptibility and resilience to coastal flooding. It is applied to nine cities around the world, each with different kinds of exposure. With the aid of this index, it is demonstrated which cities are most vulnerable to coastal flooding with regard to the system??s components, that is, hydro-geological, socio-economic and politico-administrative. The index gives a number from 0 to 1, indicating comparatively low or high coastal flood vulnerability, which shows which cities are most in need of further, more detailed investigation for decision-makers. Once its use to compare the vulnerability of a range of cities under current conditions has been demonstrated, it is used to study the impact of climate change on the vulnerability of these cities over a longer timescale. The results show that CCFVI provides a means of obtaining a broad overview of flood vulnerability and the effect of possible adaptation options. This, in turn, will allow for the direction of resources to more in-depth investigation of the most promising strategies.     

Spatial exposure aspects contributing to vulnerability and resilience assessments of urban critical infrastructure in a flood and blackout context

Blackouts aggravate the situation during an extreme river-flood event by affecting residents and visitors of an urban area. But also rescue services, fire brigades and basic urban infrastructure such as hospitals have to operate under suboptimal conditions. This paper aims to demonstrate how affected people, critical infrastructure, such as electricity, roads and civil protection infrastructure are intertwined during a flood event, and how this can be analysed in a spatially explicit way. The city of Cologne (Germany) is used as a case study since it is river-flood prone and thousands of people had been affected in the floods in 1993 and 1995. Components of vulnerability and resilience assessments are selected with a focus of analysing exposure to floods, and five steps of analysis are demonstrated using a geographic information system. Data derived by airborne and spaceborne earth observation to capture flood extent and demographic data are combined with place-based information about location and distance of objects. The results illustrate that even fire brigade stations, hospitals and refugee shelters are within the flood scenario area. Methodologically, the paper shows how criticality of infrastructure can be analysed and how static vulnerability assessments can be improved by adding routing calculations. Fire brigades can use this information to improve planning on how to access hospitals and shelters under flooded road conditions.

     

城市洪水灾害易损性多属性动态评价

近年来极端天气事件频发,尤其洪水灾害日趋频繁并且影响深远。在众多易损性概念基础上,进一步明确了城市易损性的内涵,并构建了城市洪水灾害易损性的评价指标体系。针对传统多属性决策方法——逼近理想解排序法(TOPSIS)不能比较正、负理想解中垂线上点的问题,采用Kullback-Leibler距离计算评价对象与正理想解的贴近度,建立了KL-TOPSIS模型,应用该模型对哈尔滨市2005~2009年洪水灾害易损性进行了动态评价,得出其易损性先升后降的结论,并通过横向比较发现哈尔滨市的洪水灾害易损性要小于同时期的沈阳市、武汉市和上海市。