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.     

Estimation of structural vulnerability for flooding using geospatial tools in the rural area of Orissa,India

Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa, India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage). Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation.     

Spatial scan statistics in vulnerability assessment: an application to mountain hazards

In the European Alps, the concept of risk has increasingly been applied in order to reduce the susceptibility of society to mountain hazards. Risk is defined as a function of the magnitude and frequency of a hazard process times consequences; the latter being quantified by the value of elements at risk exposed and their vulnerability. Vulnerability is defined by the degree of loss to a given element at risk resulting from the impact of a natural hazard. Recent empirical studies suggested a dependency of the degree of loss on the hazard impact, and respective vulnerability (or damage-loss) functions were developed. However, until now, only little information is available on the spatial characteristics of vulnerability on a local scale; considerable ranges in the loss ratio for medium process intensities only provide a hint that there might be mutual reasons for lower or higher loss rates. In this paper, we therefore focus on the spatial dimension of vulnerability by searching for spatial clusters in the damage ratio of elements at risk exposed. By using the software SaTScan, we applied an ordinal data model and a normal data model in order to detect spatial distribution patterns of five individual torrent events in Austria. For both models, we detected some significant clusters of high damage ratios, and consequently high vulnerability. Moreover, secondary clusters of high and low values were found. Based on our results, the assumption that lower process intensities result in lower damage ratios, and therefore in lower vulnerability, and vice versa, has to be partly rejected. The spatial distribution of vulnerability is not only dependent on the process intensities but also on the overall land use pattern and the individual constructive characteristics of the buildings exposed. Generally, we suggest the use of a normal data model for test sites exceeding a minimum of 30 elements at risk exposed. As such, the study enhanced our understanding of spatial vulnerability patterns on a local scale.     

Prioritization of disaster risk in a community using GIS

Prioritization of disaster risk was carried out for a community in Toronto, Canada. Geographic information systems (GIS) were used for spatial analysis, including spatial overlays and clipping for extracting spatial and attribute information related to people’s vulnerability, critical infrastructure and landuse. In order to determine disaster risk, the overall community vulnerability was evaluated by combining social, economic, physical and environmental vulnerabilities. This paper uses the propane explosion incident as the case in point to demonstrate the methodology and procedure used to evaluate risk using GIS techniques. City of Toronto spatial data have been integrated with the study area to gather landuse information, identify risk zones based on the propane storage facility location and evaluate risks. Statistics Canada 2006 census data have been used for area demographics and people’s social and economic status. Vulnerability indicators were determined based on the GIS-derived spatial and attribute data for the hazard and evacuation zones followed by a quantitative spatial risk estimation and ranking. The methodology of this study, based on the risk evaluation and prioritization conducted, can be applied to future decision making in effective landuse planning and the development of risk management strategies.     

Assessment of climate change impacts on flooding vulnerability for lowland management in southwestern Taiwan

Taiwan suffers from losses of economic property and human lives caused by flooding almost every year. Flooding is an inevitable, reoccurring, and the most damaging disaster in Taiwan since Taiwan is located in the most active tropic cyclone formation region of the Western Pacific. Flooding problem is further worse in land subsidence areas along southwestern coast of Taiwan due to groundwater overdraft. Increasing number of people is threatened with floods owing to climate change since it would induce sea level rise and intensify extreme rainfall. Assessments of flooding vulnerability depend not only on flooding severity, possible damage of assets exposed to floods should also be simultaneously considered. This paper aims at exploring how climate change might impact the flooding vulnerability of lowland areas in Taiwan. A flooding vulnerability evaluation scheme is proposed in this study which incorporates flooding severity (the maximum inundation depth determined by a two-dimensional model) and potential economic losses for various land uses. Effects of climate change on flooding vulnerability focus on alterations of rainfall depth for various recurrence intervals. The flood-prone Yunlin coastal area, located in southwestern Taiwan, is chosen to illustrate the proposed methodology. The results reveal that reducing flooding vulnerability can be achieved by either reducing flooding severity (implementation of flood-mitigation measures) or decreasing assets exposed to floods (suspension of land uses for flood-detention purpose). Performance of currently implemented flood-mitigation measures is insufficient to reduce flooding vulnerability when facing with climate change. However, the scenario suggested in this study to sustain room for floods efficiently reduces flooding vulnerability in both without- and with climate change situations. The suggestions provided in this study could support decision processes and help easing flooding problems of lowland management in Taiwan under climate change.     

Vulnerability profiles of forested landscape to climate change in Bengal Duars region,India

This paper assesses village level vulnerability profiles of the forested landscape in Bengal Duars region. Vulnerability of forested landscape is addressed by indicator-based approach with finer details using GIS-based interactive model under present climate. The three integrant of vulnerability are inscribed: exposure, sensitivity and adaptive capacity, by taking into consideration of twenty-one environmental and socio-economic indicators are identified. Being located in the foothills of Eastern Himalaya sudden variation of slope in Bengal Duars region results in frequent flooding and huge damage to forested landscape. Change of climate, degradation of forest resources and socio-economic backwardness further enhances the degree of vulnerability. It has been detected that 61% of area in Bengal Duars is configured to be vulnerable to climate change. The most vulnerable areas are the forested cover in Jalpaiguri, Baikunthapur, Wildlife-II, Wildlife-III, and Buxa Tiger Reserve East and their surrounding landscape with more climatic variation, disrupted by anthropogenic and non-climatic activities and less access to infrastructural and socioeconomic facilities.     

Vulnerability to natural disasters in Serbia: spatial and temporal comparison

The frequency of natural disasters and the extent of their consequences at a global level are constantly increasing. This trend is partially caused by increased population vulnerability, which implies the degree of population vulnerability due to high-magnitude natural processes. This paper presents an analysis of vulnerability to natural disaster in Serbia in the second half of the twentieth and the early twenty-first century. Vulnerability changes were traced on the basis of demographic–economic indicators derived from statistical data for local government units (municipalities) provided by the Statistical Office of the Republic of Serbia. Calculations were performed in the geographical information system environment. The results of the study show that spatial and temporal vulnerability variations are causally correlated with changes in the selected components. Significant rise of vulnerability is related to urban areas, while lower values are characteristic for other areas of Serbia; this is primarily a consequence of different population density.     

Comparative Risk Assessments for the City of Cologne – Storms, Floods, Earthquakes

In this paper a methodology for a multi-risk assessment of an urban area is introduced and performed for the city of Cologne, Germany, considering the natural hazards windstorm, flooding and earthquake. Moreover, sources of the uncertainty in the analysis and future needs for research are identified. For each peril the following analyses were undertaken: hazard assessment, vulnerability assessment and estimation of losses. To compare the three hazard types on a consistent basis, a common economic assessment of exposed assets was developed. This was used to calculate direct economic losses to buildings and their contents. The perils were compared by risk curves showing the exceedence probability of the estimated losses. In Cologne, most of the losses that occur frequently are due to floods and windstorms. For lower return periods (10–200 years) the risk is dominated by floods. For return periods of more than 200 years the highest damage is caused by earthquakes.     

A quantitative vulnerability function for fluvial sediment transport

In quantitative risk assessment, risk is expressed as a function of hazard, elements at risk exposed, and vulnerability. Vulnerability is defined as the expected degree of loss for an element at risk as a consequence of a certain event, following a natural-scientific approach combined with economic methods of loss appraisal. The resulting value ranges from 0 (no damage) to 1 (complete destruction). With respect to torrent processes, i.e., fluvial sediment transport, this concept of vulnerability—though widely acknowledged—did not result in sound quantitative relationships between process intensities and associated degrees of loss so far, even if considerable loss occurred during recent years. To close this gap and establish this relationship, data from three well-documented torrent events in the Austrian Alps were used to derive a quantitative vulnerability function applicable to residential buildings located on torrent fans. The method applied followed a spatially explicit empirical approach within a GIS environment and was based on process intensities, the spatial characteristics of elements at risk, and average reconstruction values on a local scale. Additionally, loss data were collected from responsible administrative bodies and analysed on an object level. The results suggest a modified Weibull distribution to fit best to the observed damage pattern if intensity is quantified in absolute values, and a modified Frechet distribution if intensity is quantified relatively in relation to the individual building height. Additionally, uncertainties resulting from such an empirical approach were studied; in relation to the data quality a 90% confidence band was found to represent the data range appropriately. The vulnerability relationship obtained allows for an enhanced quantification of torrent risk, but also for an inclusion in comprehensive vulnerability models including physical, social, economic, and institutional vulnerability. As a result, vulnerability to mountain hazards might decrease in the future.     

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.     

A 3-tier tsunami vulnerability assessment technique for the north-west coast of Peninsular Malaysia

The 2004 tsunami that struck the Sumatra coast gave a warning sign to Malaysia that it is no longer regarded as safe from a future tsunami attack. Since the event, the Malaysian Government has formulated its plan of action by developing an integrated tsunami vulnerability assessment technique to determine the vulnerability levels of each sector along the 520-km-long coastline of the north-west coast of Peninsular Malaysia. The scope of assessment is focused on the vulnerability of the physical characteristics of the coastal area, and the vulnerability of the built environment in the area that includes building structures and infrastructures. The assessment was conducted in three distinct stages which stretched across from a macro-scale assessment to several local-scale and finally a micro-scale assessment. On a macro-scale assessment, Tsunami Impact Classification Maps were constructed based on the results of the tsunami propagation modelling of the various tsunami source scenarios. At this stage, highly impacted areas were selected for an assessment of the local hazards in the form of local flood maps based on the inundation modelling output. Tsunami heights and flood depths obtained from these maps were then used to produce the Tsunami Physical Vulnerability Index (PVI) maps. These maps recognize sectors within the selected areas that are highly vulnerable to a maximum tsunami run-up and flood event. The final stage is the development of the Structural Vulnerability Index (SVI) maps, which may qualitatively and quantitatively capture the physical and economic resources that are in the tsunami inundation zone during the worst-case scenario event. The results of the assessment in the form of GIS-based Tsunami-prone Vulnerability Index (PVI and SVI) maps are able to differentiate between the various levels of vulnerability, based on the tsunami height and inundation, the various levels of impact severity towards existing building structures, property and land use, and also indicate the resources and human settlements within the study area. Most importantly, the maps could help planners to establish a zoning scheme for potential coastline development based on its sensitivity to tsunami. As a result, some recommendations on evacuation routes and tsunami shelters in the potentially affected areas were also proposed to the Government as a tool for relief agencies to plan for safe evacuation.     

A multi-dimensional assessment of urban vulnerability to climate change in Sub-Saharan Africa

In this paper, we develop and apply a multi-dimensional vulnerability assessment framework for understanding the impacts of climate change-induced hazards in Sub-Saharan African cities. The research was carried out within the European/African FP7 project CLimate change and Urban Vulnerability in Africa, which investigated climate change-induced risks, assessed vulnerability and proposed policy initiatives in five African cities. Dar es Salaam (Tanzania) was used as a main case with a particular focus on urban flooding. The multi-dimensional assessment covered the physical, institutional, attitudinal and asset factors influencing urban vulnerability. Multiple methods were applied to cover the full range of vulnerabilities and to identify potential response strategies, including: model-based forecasts, spatial analyses, document studies, interviews and stakeholder workshops. We demonstrate the potential of the approach to assessing several dimensions of vulnerability and illustrate the complexity of urban vulnerability at different scales: households (e.g., lacking assets); communities (e.g., situated in low-lying areas, lacking urban services and green areas); and entire cities (e.g., facing encroachment on green and flood-prone land). Scenario modeling suggests that vulnerability will continue to increase strongly due to the expected loss of agricultural land at the urban fringes and loss of green space within the city. However, weak institutional commitment and capacity limit the potential for strategic coordination and action. To better adapt to urban flooding and thereby reduce vulnerability and build resilience, we suggest working across dimensions and scales, integrating climate change issues in city-level plans and strategies and enabling local actions to initiate a ‘learning-by-doing’ process of adaptation.

     

Experimental vulnerability curves for the residential buildings of Iran

Iran is one of the most seismically active countries of the world located on the Alpine-Himalayan earthquake belt. More than 180,000 people were killed due to earthquakes in Iran during the last five decades. Considering the fact that most Iranians live in masonry and non-engineered houses, having a comprehensive program for decreasing the vulnerability of society holds considerable importance. For this reason, loss estimation should be done before an earthquake strikes to prepare proper information for designing and selection of emergency plans and the retrofitting strategies prior to occurrence of earthquake. The loss estimation process consists of two principal steps of hazard analysis and vulnerability assessment. After identifying the earthquake hazard, the first step is to evaluate the vulnerability of residential buildings and lifelines and also the social and economic impacts of the earthquake scenarios. Among these, residential buildings have specific importance, because their destruction will disturb the daily life and result in casualties. Consequently, the vulnerability assessment of the buildings in Iran is important to identify the weak points in the built environment structure. The aim of this research is to prepare vulnerability curves for the residential buildings of Iran to provide a proper base for estimating probable damage features by future earthquakes. The estimation may contribute fundamentally for better seismic performance of Iranian societies. After a brief review of the vulnerability assessment methods in Iran and other countries, through the use of the European Macroseismic method, a model for evaluating the vulnerability of the Iranian buildings is proposed. This method allows the vulnerability assessment for numerous sets of buildings by defining the vulnerability curves for each building type based on the damage observations of previous earthquakes. For defining the vulnerability curves, a building typology classification is presented in this article, which is representative of Iranian building characteristics. The hazard is described in terms of the macroseismic intensity and the EMS-98 damage grades have been considered for classifying the physical damage to the buildings. The calculated vulnerability indexes and vulnerability curves show that for engineered houses there is not any notable difference between the vulnerability of Iranian and Risk-UE building types. For the non-engineered houses, the vulnerability index of brick and steel structures is less than the corresponding values of the other unreinforced masonry buildings of Iran. The vulnerability index of unreinforced and masonry buildings of Iran are larger than the values of the similar types in Risk-UE and so the Iranian buildings are more vulnerable in this regard.     

A multi-dimensional assessment of urban vulnerability to climate change in Sub-Saharan Africa

In this paper, we develop and apply a multi-dimensional vulnerability assessment framework for understanding the impacts of climate change-induced hazards in Sub-Saharan African cities. The research was carried out within the European/African FP7 project CLimate change and Urban Vulnerability in Africa, which investigated climate change-induced risks, assessed vulnerability and proposed policy initiatives in five African cities. Dar es Salaam (Tanzania) was used as a main case with a particular focus on urban flooding. The multi-dimensional assessment covered the physical, institutional, attitudinal and asset factors influencing urban vulnerability. Multiple methods were applied to cover the full range of vulnerabilities and to identify potential response strategies, including: model-based forecasts, spatial analyses, document studies, interviews and stakeholder workshops. We demonstrate the potential of the approach to assessing several dimensions of vulnerability and illustrate the complexity of urban vulnerability at different scales: households (e.g., lacking assets); communities (e.g., situated in low-lying areas, lacking urban services and green areas); and entire cities (e.g., facing encroachment on green and flood-prone land). Scenario modeling suggests that vulnerability will continue to increase strongly due to the expected loss of agricultural land at the urban fringes and loss of green space within the city. However, weak institutional commitment and capacity limit the potential for strategic coordination and action. To better adapt to urban flooding and thereby reduce vulnerability and build resilience, we suggest working across dimensions and scales, integrating climate change issues in city-level plans and strategies and enabling local actions to initiate a ‘learning-by-doing’ process of adaptation.     

Coastal inundation and damage exposure estimation: a case study for Jakarta

Coastal flooding poses serious threats to coastal areas, and the vulnerability of coastal communities and economic sectors to flooding will increase in the coming decades due to environmental and socioeconomic changes. It is increasingly recognised that estimates of the vulnerability of cities are essential for planning adaptation measures. Jakarta is a case in point, since parts of the city are subjected to regular flooding on a near-monthly basis. In order to assess the current and future coastal flood hazard, we set up a GIS-based flood model of northern Jakarta to simulate inundated area and value of exposed assets. Under current conditions, estimated damage exposure to extreme coastal flood events with return periods of 100 and 1,000 years is high (€4.0 and €5.2 billion, respectively). Under the scenario for 2100, damage exposure associated with these events increases by a factor 4–5, with little difference between low/high sea-level rise scenarios. This increase is mainly due to rapid land subsidence and excludes socioeconomic developments. We also develop a detemporalised inundation scenario for assessing impacts associated with any coastal flood scenario. This allows for the identification of critical points above which large increases in damage exposure can be expected and also for the assessment of adaptation options against hypothetical user-defined levels of change, rather than being bound to a discrete set of a priori scenarios. The study highlights the need for urgent attention to the land subsidence problem; a continuation of the current rate would result in catastrophic increases in damage exposure.     

A new hybrid procedure for the definition of seismic vulnerability in Mediterranean cross-border urban areas

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model.

     

A new hybrid procedure for the definition of seismic vulnerability in Mediterranean cross-border urban areas

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model.     

A conceptual framework for quantitative estimation of physical vulnerability to landslides

The paper illustrates a method for scenario-based, quantitative estimation of physical vulnerability of the built environment to landslides. The rationale and main features of the procedure are presented in the context of quantitative risk estimation. Vulnerability is defined quantitatively as a function of landslide intensity and the susceptibility of vulnerable elements. Reference terminology is presented and discussed. Models for the quantification of intensity and susceptibility for some categories of elements at risk such as structures and persons are proposed. An example application is illustrated.     

鄱阳湖水患区危险性分区评价

水患危险性分区评价就是在查明区域环境地质背景的前提下,对水患灾害发生的规模、强度、频次,灾害活动的孕育条件、变化规律,以及成灾过程中密切相关的人类社会经济特征,诸如人口、财产、工程建设活动、资源开发、经济发展水平、防灾能力等进行调研,同时还必须对水患的危害范围、破坏程度进行调研,并在此基础上对其做出全面而综合的评价。简言之,水患危险性分区评价就是分区对其危险性、易损性、破坏损失性、防灾工程效益进行全面而综合的评价。据此,本文将鄱阳湖水患区划分为3个高风险区(南昌市区、九江市区及永安堤段高风险区)和5个一般风险区(赣江尾闾、抚河尾闾、修河尾闾、信江尾闾及饶河尾闾一般风险区)。