Property Level Flood Research Articles

Does flood risk affect property prices? Evidence from a property-level flood score

One in six properties in England is exposed to flood risk and around half of those affected properties can be characterised as high risk. In this paper we examine whether the probability of flooding is capitalised in England's property market prices. We use unique property-level data from Rightmove, UK's no.1 property website and the property-level FloodScoreTMby Twinn, Royal HaskoningDHV. The latter is a metric of objective flood risk based on the likelihood of an individual property being flooded due to rainfall, overflowing rivers and tidal surges and is commonly used by UK lenders. By comparing the unconditional averages of our data, we find that properties at risk are sold at an 8.14 % discount compared to non-exposed properties, and the price discount increases to 32.2 % for properties with very high flood risk. By 2080 the flood events are expected to become more frequent and the average flood risk is projected to increase by 8 %. Our empirical model suggests that one percentage point increase in properties' flood risk is associated with a decline of 0.07 % to 0.11 % in both sold and asking property prices. The impact is higher for properties of which flood risk is expected to increase or for regions that have recently experienced a flood event.

Toward disaster resilience in property management: the nomenclature of structural and non-structural building adaptation measures relative to flood exposure

PurposeThe study aims to investigate the nomenclature of structural versus non-structural building adaptation measures taken by occupants of residential properties located in flood-prone areas of Port Harcourt, Nigeria, to verify whether they are adapted or maladapted relative to their level of flood exposure and underscore the role of disaster resilience in property management.Design/methodology/approachUsing the survey research strategy, the uptake of structural and non-structural adaptation measures in spatially distributed areas of Port Harcourt was descriptively analyzed and tested to identify significant variation in the uptake of adaptation measures relative to increasing flooding levels, using a one-way ANOVA.FindingsThe study outcome reveals that there are some distinctive features of buildings in Port Harcourt which provide wet-proofing structural adaptation qualities while dry-proofing structural adaptation measures are not adequate. However, although some key structural adaptation measures were adapted relative to the levels of flood exposure, most structural features of the buildings do not vary relative to flooding levels, indicating maladaptation even with increasing flood risk. The uptake of non-structural measures is also inadequate and maladapted relative to changes in the level of flood exposure, despite their non-intrusive and low-cost nature. Overall, the findings imply that maladaptation is more prevalent.Originality/valueThe study provides a descriptive snapshot of the nomenclature of property-level flood risk adaptation in residential buildings, while highlighting the maladaptive tendencies/behavior of property occupants, within a metropolitan setting in the developing world, necessary to inform policy and provide sensitization for fostering disaster resilience in property management.

Cloud Modelling of Property-Level Flood Exposure in Megacities

Surface water flood risk is projected to increase worldwide due to the growth of cities as well as the frequency of extreme rainfall events. Flood risk modelling at high resolution in megacities is now feasible due to the advent of high spatial resolution terrain data, fast and accurate hydrodynamic models, and the power of cloud computing platforms. Analysing the flood exposure of urban features in these cities during multiple storm events is essential to understanding flood risk for insurance and planning and ultimately for designing resilient solutions. This study focuses on London, UK, a sprawling megacity that has experienced damaging floods in the last few years. The analysis highlights the key role of accurate digital terrain models (DTMs) in hydrodynamic models. Flood exposure at individual building level is evaluated using the outputs from the CityCAT model driven by a range of design storms of different magnitudes, including validation with observations of a real storm event that hit London on the 12 July 2021. Overall, a novel demonstration is presented of how cloud-based flood modelling can be used to inform exposure insurance and flood resilience in cities of any size worldwide, and a specification is presented of what datasets are needed to achieve this aim.

Living with water: quantitative assessment of property-level resilience to urban flooding

Purpose This paper aims to quantitively assess the resilience of residential properties to urban flooding in Port Harcourt, Nigeria, and assess whether they vary at spatially aggregated scales relative to the level of flood exposure. Design/methodology/approach The study synthesizes theoretical constructs/indicators for quantifying property level resilience, as a basis for measuring resilience. Using a two-stage purposive/stratified randomized sampling approach, 407 questionnaires were sent out to residents of 25 flood-prone areas, to solicit information on the resilience constructs as indicated by the adaptation behaviors of individual households and their property attributes. A principal component analysis approach is used as a mechanism for weighting the indicators, based on which aggregated spatial-scale resilience indices were computed for the 25 sampled areas relative to their levels of flood exposure. Findings Area 11 located in the moderate flood zone has the lowest resilience index, while Area 20 located in the high flood zone has the highest resilience index. The resilience indices for the low, moderate and high flood zone show only minimal and statistically insignificant differences indicating maladaptation even with incremental levels of flood exposure. Practical implications The approach to resilience measurement exemplifies a reproducible lens through which the concept of “living with floods” can be holistically assessed at the property level while highlighting the nexus of the social and technical dimensions. Originality/value The study moves beyond theoretical conceptualization, to empirically quantify the complex concept of property-level flood resilience.

Property level flood risk adaptation: technical and socioeconomic dimensions to resilience

PurposeUnderstanding the technical and socioeconomic dimensions to resilience is core to making a business case for property-level flood risk adaptation. The study investigates the socioeconomic factors that impact the technical dimensions to property-level flood risk adaptation, and whether there is a typology of households adopting similar adaptation measures in Port Harcourt.Design/methodology/approachExploratory and inferential statistical analysis of data collated from 407 questionnaires was carried out. Using chi-square analysis, significant bivariate associations were sought between the level of uptake of different categories of property level adaptation and the socioeconomic characteristics of households. A two-step cluster analysis was used to explore discernible patterns of households implementing similar adaptation measures. Logistic regression analysis was further used to evaluate the extent to which socioeconomic parameters impact residents' willingness to undertake adaptation measures given the option of relocation.FindingsThe chi-square analysis highlighted a lack of significant association between some socioeconomic parameters and the uptake of individual adaptation measures. The regression analysis however showed that the socioeconomic parameters exert varying degrees of influence on the residents' willingness to undertake adaptation measures. Two homogeneous groups of residents with similar socioeconomic characteristics were identified via the cluster analysis but did not translate into strongly discernible adaptation differences/patterns.Practical implicationsThe study shows that although socioeconomic parameters to some extent underlie the technical dimensions to flood resilience, there is no distinctive typology of households in Port Harcourt adopting a similar combination of measures.Originality/valueThe study offers insights into understanding property-level flood risk adaptation responses within the context of the developing world.

The potential for property-level flood adaptation as a flood disaster mental health intervention

ObjectivesThis study aimed to discuss the overlap between property-level flood adaptation and public health and flood risk management and identify areas of future research. Design and MethodsA short essay-based contribution arguing in favour of a future research direction from the perspective of a disaster risk researcher. ResultsPromoting property-level flood adaption has multiple areas of benefit to both flooding and mental health risk management as a potential invention. This is because both fields display common interests in enabling and promoting personal responsibility to limit disaster consequences and build resilience. ConclusionsThe promotion and development of property-level flood adaptation strategies can be a productive locus of behaviour for further active collaboration and research, as well as a joint intervention for improving human welfare postdisaster. However, more proactive research is required.

Accuracy Assessment of Surveying Strategies for the Characterization of Microtopographic Features That Influence Surface Water Flooding

With the increase in rainfall intensity, population, and urbanised areas, surface water flooding (SWF) is an increasing concern impacting properties, businesses, and human lives. Previous studies have shown that microtopography significantly influences flow paths, flow direction, and velocity, impacting flood extent and depth, particularly for the shallow flow associated with urban SWF. This study compares two survey strategies commonly used by flood practitioners, S1 (using Unmanned Aerial Systems-based RGB data) and S2 (using manned aircraft with LiDAR scanners), to develop guidelines on where to use each strategy to better characterise microtopography for a range of flood features. The difference between S1 and S2 in elevation and their accuracies were assessed using both traditional and robust statistical measures. The results showed that the difference in elevation between S1 and S2 varies between 11 cm and 37 cm on different land use and microtopographic flood features. Similarly, the accuracy of S1 ranges between 3 cm and 70 cm, and the accuracy of S2 ranges between 3.8 cm and 30.3 cm on different microtopographic flood features. Thus, this study suggests that the flood features of interest in any given flood study would be key to select the most suitable survey strategy. A decision framework was developed to inform data collection and integration of the two surveying strategies to better characterise microtopographic features. The findings from this study will help improve the microtopographic representation of flood features in flood models and, thus, increase the ability to identify high flood-risk prompt areas accurately. It would also help manage and maintain drainage assets, spatial planning of sustainable drainage systems, and property level flood resilience and insurance to better adapt to the effects of climate change. This study is another step towards standardising flood extent and impact surveying strategies.

Investigating moral hazard and property-level flood resilience measures through panel data from Germany

Property-level flood resilience is an important element of managing current and future flood risk. Government-provided flood protection infrastructure alone cannot fully prevent flood impacts. Property-level flood resilience can aid in the management of risk through two interconnected avenues of individual action. The first is through risk transfer (insurance), which provides post-disaster compensation so that the recovery process is enhanced. The second is through property-level resilience measures, which are strategies aimed at limiting flood damage. Well-designed insurance schemes could incentivise insurance policyholders to employ additional property-level flood resilience measures. However, insurance can equally be argued to disincentivise the employment of property-level flood resilience measures, as the policyholder's losses will be compensated by an insurance company. This latter impact has been referred to as moral hazard, and its systematic presence in disaster insurance markets jeopardizes the industry's sustainability. However, the presence of moral hazard is context dependent. Therefore, it is necessary to study whether moral hazard is present to understand how resilient society is. We study the presence of moral hazard in Germany using a panel dataset, resulting from a longitudinal survey following a flood in 2013. The panel provides insights into dynamic mechanisms concerning moral hazard that would remain hidden in a cross-sectional survey, a dataset that is more widely used in the current literature. We did not find indications for the presence of moral hazard in Germany overall, but a continuing positive association between insurance purchases and the employment of flood resilience measures despite the overall increasing coverage rates.

The Economic Impact of Flood Zone Designations on Residential Property Valuation in Miami-Dade County

In the United States, flood events are the most economically damaging type of natural disaster. Some of the most widely used tools for understanding property flood risk in the United States are the Flood Insurance Rate Maps (FIRMs) produced by the Federal Emergency Management Agency (FEMA). Numerous previous studies have attempted to estimate the impact on property valuation from a home’s being mapped into a Special Flood Hazard Area (SFHA) within FIRMs. However, as these maps have widely served as the source of data about true flood risk, there have been limits on the ability of researchers to disentangle these zone designation impacts as due to actual flood risk or as due to perceived flood risk. New advancements in flood modeling have allowed for the prediction of high-quality property-level flood inundation, both now and in the future. By integrating these flood modeling advancements, true flood risk may be controlled for in models looking to explore the avenues by which property valuation impacts occur. To this end, this study builds on insights from recent research looking at the valuation of single-family residential properties in Miami-Dade County (MDC), which utilizes a high-resolution floodplain model to estimate the impact of actual property inundation on sales prices. By controlling for actual property flood risk, impacts of SFHA designations are estimated in MDC through implementation of a difference in difference model which utilizes the release of updated FIRMS in 2009 and the 217,222 transactions and 120,693 property designation changes which occurred within the dataset.

How does flood resistance affect learning from flood experiences? A study of two communities in Central China.

Property-level flood risk adaptation (PLFRA) has received significant attention in recent years, as flood resilience has become increasingly important in flood risk management. Earlier studies have indicated that learning from flood experiences can affect flood risk perception and the adoption of PLFRA measures; however, it remains unclear whether and how this learning process can be affected by flood control infrastructure—specifically, the level of flood resistance it offers. This study attempts to answer the question: Do people living in environments with different levels of flood resistance learn different lessons from flood experience, manifested in flood risk perception and PLFRA? We present a comparative study of the rural village of Xinnongcun and the urban community of Nanhuyayuan in Central China. In-person interviews with a total of 34 local residents were conducted to understand how flood experiences affect flood risk perception and PLFRA. We find that learning from flood experiences in the highly flood-resistant environment (Nanhuyayuan) does not contribute to flood risk perception but further enhances flood resistance, whereas learning in a less flood-resistant environment (Xinnongcun) leads to a better understanding of flood risk and promotes PLFRA. We argue that flood resistance can affect the learning from flood experiences. High flood resistance can suppress PLFRA through a different learning process that involves learning inertia and path dependency. In the search for flood resilience, this begs society to re-examine the widespread assertion that both structural and nonstructural measures are important in flood risk management.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10584-022-03401-3.

Leveraging Hazard, Exposure, and Social Vulnerability Data to Assess Flood Risk to Indigenous Communities in Canada

This study integrates novel data on 100-year flood hazard extents, exposure of residential properties, and place-based social vulnerability to comprehensively assess and compare flood risk between Indigenous communities living on 985 reserve lands and other Canadian communities across 3701 census subdivisions. National-scale exposure of residential properties to fluvial, pluvial, and coastal flooding was estimated at the 100-year return period. A social vulnerability index (SVI) was developed and included 49 variables from the national census that represent demographic, social, economic, cultural, and infrastructure/community indicators of vulnerability. Geographic information system-based bivariate choropleth mapping of the composite SVI scores and of flood exposure of residential properties and population was completed to assess the spatial variation of flood risk. We found that about 81% of the 985 Indigenous land reserves had some flood exposure that impacted either population or residential properties. Our analysis indicates that residential property-level flood exposure is similar between non-Indigenous and Indigenous communities, but socioeconomic vulnerability is higher on reserve lands, which confirms that the overall risk of Indigenous communities is higher. Findings suggest the need for more local verification of flood risk in Indigenous communities to address uncertainty in national scale analysis.

Flood-Resilient Communities: How We Can Encourage Adaptive Behaviour Through Smart Tools in Public–Private Interaction

To achieve a more flood-resilient society, it is essential to involve citizens. Therefore, new instruments, such as tailor-made advice for homeowners, are being developed to inform homeowners about adaptive strategies in building to motivate them to implement these measures. This article evaluates if public–private interactions, such as tailored advice, change risk behaviour and therefore increase flood resilience among homeowners. The article conducted semi-structured interviews with homeowners who had received advice as well as involved experts in two case study regions in Europe: Flanders in Belgium and Vorarlberg in Austria. The results show how the tailored advice helps homeowners who are already aware of flood risks and provides them with answers on how to adapt a house. However, the tool seems to lack the ability to inform and “recruit” new groups of homeowners who are not as familiar with flood risks. As such, this article concludes that this initiative has a relatively low impact in raising flood risk awareness among homeowners but may be more successful in serving as a tool that suggests tailored property-level flood risk adaptation measures for those who are already aware. Alternatively, more automated tailored information systems might be more efficient for unaware homeowners.

Towards more effective strategies to reduce property level flood risk: standardising the use of Unmanned Aerial Vehicles

Abstract Effective flood risk management strategies require a detailed understanding of the source, extent and impact of flooding. Unmanned Aerial Vehicles (UAVs) enable detailed and accurate data collection that can be used to determine flood source, extent, impact and the presence of property level flood resistance measures. This paper draws on the practical experience of the authors including the use of UAVs during flood events. We highlight the potential uses of UAVs in flood risk management activities and the associated challenges. The impact of a flooding event will also be dependent on how well an area is prepared in terms of community and property level resistance and resilience measures. We have looked at potential reasons why there is not a greater uptake of property level resistance and resilience measures. It is clear that a standardised approach is required if UAVs are to fulfil their potential within flood risk management activities. We have identified five pillars of standardisation that underpin an overarching, purpose-driven, cost-effective systems-based approach to the use of UAVs in flood risk management. These are as follows: (P1) deployment, data collection and flight-related regulatory requirements; (P2) data processing, data merging and outputs; (P3) the introduction and use of innovative approaches and technological integration; (P4) use of outputs for public engagement and (P5) policy development and governance. We consider that the proposed approach will maximise cost-effective information gathering, standardise the way processed outcomes are generated and provide the basis for comparable and robust flood risk information that is based on a single coherent methodology.

Assessing Property Level Economic Impacts of Climate in the US, New Insights and Evidence from a Comprehensive Flood Risk Assessment Tool

Hurricanes and flood-related events cause more direct economic damage than any other type of natural disaster. In the United States, that damage totals more than USD 1 trillion in damages since 1980. On average, direct flood losses have risen from USD 4 billion annually in the 1980s to roughly USD 17 billion annually from 2010 to 2018. Despite flooding’s tremendous economic impact on US properties and communities, current estimates of expected damages are lacking due to the fact that flood risk in many parts of the US is unidentified, underestimated, or available models associated with high quality assessment tools are proprietary. This study introduces an economic-focused Environmental Impact Assessment (EIA) approach that builds upon an our existing understanding of prior assessment methods by taking advantage of a newly available, climate adjusted, parcel-level flood risk assessment model (First Street Foundation, 2020a and 2020b) in order to quantify property level economic impacts today, and into the climate adjusted future, using the Intergovernmental Panel on Climate Change’s (IPCC) Representative Concentration Pathways (RCPs) and NASA’s Global Climate Model ensemble (CMIP5). This approach represents a first of its kind—a publicly available high precision flood risk assessment tool at the property level developed completely with open data sources and open methods. The economic impact assessment presented here has been carried out using residential buildings in New Jersey as a testbed; however, the environmental assessment tool on which it is based is a national scale property level flood assessment model at a 3 m resolution. As evidence of the reliability of the EIA tool, the 2020 estimated economic impact (USD 5481 annual expectation) was compared to actual average per claim-year NFIP payouts from flooding and found an average of USD 5540 over the life of the program (difference of less than USD 100). Additionally, the tool finds a 41.4% increase in average economic flood damage through the year 2050 when environmental change is included in the model.

Flood risk management in Austria: Analysing the shift in responsibility-sharing between public and private actors from a public stakeholder's perspective

The frequency and magnitude of extreme weather events are expected to increase due to the effects of climate change and socio-economic development. Potentially higher flood risk, hence, triggered debate about a shift in flood risk management from mainly public to increasingly private involvement. So far, public flood mitigation schemes were standard modes to deal with flood hazards in many countries, including Austria. With high implementation and maintenance costs as well as substantial losses remaining, alternative management approaches have increasingly been discussed. This paper analyses the debate on shifting responsibilities in flood risk management from public to private actors and whether or not the current governance arrangement would accommodate this shift in the public-private divide. Based on qualitative research, we explicitly analyse this potential shift from an institutional perspective and not from the perspective of individual homeowners, taking the case study of Dornbirn (Austria) as an example. The results show that, firstly, the current governance arrangement hardly encourages property-level flood risk adaptation measures. Secondly, several factors stabilise the current governance arrangement and prevent a shift in the public-private divide. Although the need for an increased sense of responsibility among private actors seems to be evident among interviewees, strong historical narratives and adaptive expectations lead to a society seeing public authorities to be responsible for flood risk management and trust their expertise as well as the technical flood infrastructure. However, such areas of expertise and law are fragmented and therefore impede a redistribution or enforcement of responsibilities. Furthermore, fixed costs delay a shift in the public-private divide as the traditional engineering approach (i.e. structural measures) is predominant with high investments in the current system but limited investment in risk communication to raise awareness. Yet, a shift towards sharing responsibility might contribute to flood risk management for risks to remain manageable.

“The best flood I ever had”: Contingent resilience and the (relative) success of adaptive technologies

The practical operationalisation of resilience within cities is strongly linked to technology, such as better construction materials or redesigning urban form. Institutional and private sector actors often focus on issues relating to the technological innovation journey, such as ‘pathways’ to implementation or ‘barriers’ to market uptake, rather than whether adaptive technologies are the most appropriate resilience solution. These discourses frame urban resilience from the perspective of an innovation journey where technologies are perceived to succeed if there is high uptake. However, given the multi-perspective and multi-scale nature of urban resilience, the idea of ‘success’ inevitably has complex spatial, temporal and scalar dimensions. The paper uses the case of property level flood resilience (PFR) technologies in the United Kingdom to introduce the notion of ‘contingent resilience’ as a means to understand the trade-offs that are part of assessing and evaluating climate resilient technologies. We reveal that there are fundamental contradictions in what is deemed as a ‘success’ depending on who is framing the problem, when the judgement is made, or where the scale of analysis lies. Above all, the paper highlights the importance of illuminating the struggles that do not just define success, but that spatially and temporally redistribute climate resilience in a hidden manner.

A fuzzy-analytic hierarchy process approach for measuring flood resilience at the individual property level

PurposeRecent changes in climate, rainfall patterns, snow melt and rising sea levels coupled with an increase in urban development have increased the threat of flooding. To curb these threats and mitigate these damages, property-level approaches to improving resilience are now being encouraged as part of an integrated approach to flood risk management. This raises questions such as, what are the flood resilient attributes within individual properties, what is their importance and how can these be quantified. This research sought to develop a quantitative approach for the measurement of property-level flood resilience.Design/methodology/approachA synthesis of literature was undertaken to establish the main resilient attributes and their relevant sub-attributes. This process led to the development of a new method, named the Composite Flood Resilient Index (CFRI) to weight the attributes and sub-attributes of flood resilience based on their importance. The approach adopts the use of the fuzzy-analytic hierarchy process (F-AHP) approach to quantify flood resilience.FindingsThe implications of the proposed methodology in determining the flood resilience of individual property, including the potential use in retrofitting activities, and the benefits to a range of stakeholders are considered.Social implicationsThe methodology offers the potential to support the measurement of flood resilience of individual properties, allowing the identification and prioritisation of specific interventions to improve the resilience of a property.Originality/valueWhereas previous attempts to quantify flood resilience have adopted qualitative approaches with some level of subjectivity, this proposed methodology represents an important advancement in developing a scientific and quantitative approach.

Protection Motivation Theory: A Proposed Theoretical Extension and Moving beyond Rationality—The Case of Flooding

Despite the significant financial and non-financial costs of household flooding, and the availability of products that can reduce the risk or impact of flooding, relatively few consumers choose to adopt these products. To help explain this, we combine the existing theoretical literature with evidence from 20 one-to-one discussions and three workshops with key stakeholders, as well as five round tables, to draw practical evidence of actual responses to flood risk. This analysis leads us to propose an extension to Protection Motivation Theory (PMT), which more accurately captures the decision-making process of consumers by highlighting the role of ‘ownership appraisal’. We then assess the extent to which behavioral biases impact on this revised framework. By highlighting the interaction with an augmented model of PMT and behavioral biases, the paper sheds light on potential reasons behind the fact that consumers are unlikely to adopt property-level flood resilience measures and identifies strategies to increase flood protection. The Augmented PMT suggests that policymakers might focus on increasing the Ownership Appraisal element, both directly and by targeting the creation of more supportive social norms. The work presented here opens up a wide range of areas for future research in the field.

Implementing resilience in flood risk management

Implementing resilience in flood risk management

Risk communication and adaptive behaviour in flood-prone areas of Austria: A Q-methodology study on opinions of affected homeowners.

Adaptive behaviour has become a crucial aspect in current flood risk management strategies across the globe, especially in response to potential consequences of flood hazards and facing challenges of climate change. There are several factors which influence the motivation to implement flood risk management strategies such as property-level flood risk adaptation (PLFRA) measures. This paper assesses and evaluates the role of risk communication, which is a vital and overarching driver or barrier in the successful implementation of PLFRA measures. We explored this issue through a bootstrapped Q-methodology with 20 residents in the urban area of Graz, Austria, who have been affected by flood events in the past. Additionally, semi-structured interviews concerning risk communication were conducted with the participants to understand the preferred risk communication modes. The results show that respondents have a high level of perceived self-efficacy (most have implemented PLFRA measures), that there is general distrust in public protection measures and that there is a high understanding of residual risk. Considering the communication modes preferred by a majority of respondents, face-to-face interaction with unbiased experts is more attractive than online applications. Additionally, citizens want to be engaged in decision-making processes concerning public protection measures in their area. This calls for participatory processes in flood risk management which involve mutual knowledge transfer and social learning.