FLOODrisk2020

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Web and App-based management of flood emergency plans at local entities level
(2021) Loizu, Javier; Ruiz, Amaya; Varela, Ana; Castiella, Ana; Zaragüeta, Eva; Vizcay, Nekane; Pérez, César; Sanz, Luis; Macias, Isabel
Different types of floods are frequently causing important economic and personal damages in a variety of locations within Navarre, a region located in northern Spain. Navarre is found very close to the Cantabrian sea, but only about ten percent of its area belongs to that basin, whereas ninety percent of the region belongs to the - Ebro river watershed – Mediterranean basin. Ranging from very humid oceanic climate areas to semi-deserted locations in the south of the region, floods can be caused by persistent winter fronts coming from the Atlantic ocean to very intense convective summer storm events originated in the Iberic mountain range, located to the south of Navarre. The NAdapta Life project includes actions that focus on the mitigation of flood damages. Specifically, the drafting of local emergency plans for small and medium size towns in Navarre is described here. In order to facilitate the flood emergency episodes management, computer tools have been developed for each village selected for the project. Specific websites and smartphone applications have been implemented for each local entity. Awareness, diffusion and training sessions have been carried out along with the implementation of ‘drafting and tools’ plans.
Uncertainty estimate of flood hazard for an extreme flood
(2021) Paquier, André
Hydrodynamic models are usually calibrated from historical events observations and then used for estimating the flood hazard for more extreme floods. In such a case, the uncertainty related to the calibration process is likely to be emphasized by the inadequacy of the model to describe hydraulic processes met during the flooding of additional areas. Comparing the results of various 1D and 2D models of the Besançon flooding by Doubs river for a 10,000 years return period, an estimate of the resulting uncertainty on both water depth and flow velocity is carried out. A difference of more than one metre is found for peak water levels and can be related to the features of the hydraulic models. However, this latter difference is smaller than the uncertainty range linked to the estimate of the peak discharge even if a detailed hydrological study is performed such as during the Flowres ("Predicting the flow in the floodplains with evolving land occupations during extreme flood events") project. Some conclusions are linked to the specific case of Besançon (e.g. the effect of the loop of Doubs river) but other ones are more general (e.g. representation of the urban pattern).
Assessing resilience to floods in an holistic perspective in French Polynesia
(2021) Heinzlef, C.; Morschel, J.; Serre, D.
The increase in flood events intensity and recurrence has considerably weakened urban areas and populations. The material and human damages led to social, economic, political, political and environmental impacts that can weaken the urban scale but also the national or even international scale. Faced with this, scientists and managers integrate the resilience concept into risk strategies. Resilience is defined as the ability of a system to absorb disturbances, maintain its functions and restart activities after it. However, resilience is still a concept difficult to operationalize. The objective of this research is therefore to propose an approach to address this lack of operationality. While some researches tried to operationalize the concept of resilience it is essentially a technical and organizational resilience, without taking into consideration the systemic dimension of the territory. This research therefore aims to operationalize the concept of resilience at the communal level through the creation of a decision-making tool, addressing resilience in the most holistic way possible, around three indicators in order to analyze urban, social and technical resilience characteristics. The idea behind this approach is that urban resilience embodies the abilities and capacities of a city and its population to develop before, during and after a disruptive event in order to limit its negative impacts. This scientific positioning therefore makes possible to analyze urban resilience as a continuum, highlighting proactive capacities that the urban system must develop in order to (re)act in the face of flooding. The originality of the methodology is justified by a collaborative approach, characterized by a socio-economic partnership with local actors. This approach is a part of a longer-term reflection to define the first steps in the construction of an Urban Resilience Observatory focusing on the design and dissemination of theoretical and practical knowledge around urban risk and resilience issues in order to reach the consensus needed for action and decision-making with a particular focus in French Polynesia.
Predictive condition-based monitoring for low utilisation motor driven flood risk management infrastructure
(2021) Tarrant, O.J.; Solts, K.; Carman, S.; Ugradar, Y.
This paper describes the ambition of the Environment Agency to develop and trial predictive condition-based monitoring systems for its mechanical and electrical flood risk management equipment. The aims, objective and research methods for this project are described. The challenge of developing any predictive capability for flood risk management assets which, typically have a low frequency of operation and therefore a paucity of data, is discussed. Some practical suggestions to overcome this specific challenge are presented.
How about the dikes? Managed realignment in progress at the Hedwige-Prosperpolder
(2021) Hoven, Kim van den; Kroeze, Carolien; Loon-Steensma, Jantsje M. van
Managed realignment is the landward relocation of a primary flood defence line. Because of this relocation, former land re-inundates, intertidal habitats can restore and new foreshores can develop adjacent to relocated dikes. Therefore, managed realignment can be considered a promising climate change adaptation measure that enables nature-based flood protection. This paper describes the Hedwige-Prosperpolder realignment preparations and aims to contribute to increased nature-based flood protection in future realignment projects. The Hedwige-Prosperpolder is located along the Scheldt estuary on the border of the Netherlands and Belgium. The return of tidal flow into the polder will be facilitated by dike adjustments and manmade creeks. We argue that due to climate change further research is needed on the potential of sustainable flood risk reduction by managed realignment. The Hedwige-Prosperpolder can serve as a Living Lab with many research possibilities during the realignment preparations and after the dikes will be breached. Sustainable managed realignment asks for research on the connection of the relocated dike to the intertidal habitat, both for nature restoration and for improved flood protection.
Development of flood mapping techniques and their efforts on flood assessment and management in European coastal cities
(2021) Clemente, Maria Fabrizia; Yang, Zhuyu; Barroca, Bruno
Coastal areas are highly vulnerable to climate change and, in these areas as elsewhere, the assessment and management of climate risks is a key issue. Among natural hazards, flood is one of the most damaging. Flood mapping supports risk assessment and management. In the last decade, new technologies have allowed many innovations in cartography, both in the data acquisition, processing, and modelling phases. In flood mapping, the identification of data and the methodological approach are the first key aspects. Other fundamental aspects are the visualization, transfer and communication of data to different users. Graphic semiology is the discipline that identifies the techniques that make data usable. In this contribution, key steps of flood mapping are analysed, through the study of techniques and products. Furthermore, possible directions for mapping research and development to support flood assessment and management are identified. To validate the theories, the process of developing a flood risk map of road system will be illustrated.
Current and future flood risk in the Danube region using an open loss modelling framework
(2021) Schröter, Kai; Steinhausen, Max; Wortmann, Michel; Lüdtke, Stefan; Hayes, Ben; Drews, Martin; Hattermann, Fred; Kreibich, Heidi
Climate informee planning of adaptation actions requires consistent and reliable information about future risks as well as appropropriate tools and services to support comprehensive flood risk assessment and management. The Future Danube Model is a multi-hazard and risk model suite to provide spatially consistent information on current and future extreme events and to quantify climate risks. The Future Danube Model is composed of exchangeable modules for climate input, hydrology, inundation, flood damage and risk. It is implemented within an open source platform, the OASIS Loss Modelling Framework. The application of the Future Danube Model is showcased for the assessment of current and future flood risk to residential buildings in the Danube region. Outputs from Global and Regional Climate Models for a reference period and three future climate periods are used to drive the model chain. Results show predominantly an increase in peak discharges across the Danube basin with exception for the Moldava and Tisza rivers. Future fluvial flood risk is shown to most likely increase in the future which is more pronounced for the high-end RCP84 scenario.
Detection of seepages and monitoring of structural changes in earthen embankments by FO DTS
(2021) Čejka, Filip; Beneš, Vojtěch; Benei, Balázs; Boukalová, Zuzana
The aim of this paper is to describe an innovation in the monitoring of performance of earth embankments, namely the use of sensing systems for full-time monitoring of ash pond and irrigation pond seepages. In the past decades, due to IT development and cost reduction, the sensor technology segment and associated measurement and monitoring systems have started to expand rapidly. One of the areas of sensor technology suitable for real-time monitoring of earthen embankments is that of fibre optic distributed temperature sensors (FO DTS). This paper deals with the results of pilot measurements performed within the E!11705 FORMTES project in 2018 – 2020, as related to the analysis of the existing FO DTS system installed in the irrigation pond in Spain, and on the new implementation of the FO DTS system in part of the embankment of the ash pond in Hungary, and the use of FO DTS systems for monitoring of potential seepage in above mentioned embankment structures. The evaluated pilot tests together with the desk review were used for the validation and enhancement of the novel methodology to enable its real-life implementation both for the existing embankment structures and the development of detailed designs of new structures of similar nature.
Acknowledging residual risk behind dikes: Examples from the USA, Quebec (Canada) and France
(2021) Serra-Llobet, Anna; Tourment, Rémy; Montané, Antonin; Buffin-Belanger, Thomas
Although hydraulic infrastructure such as levees remain important for flood risk management in the USA, France, and Quebec (Canada), there is increasing emphasis on non-structural measures, such as regulatory flood maps, to reduce exposure and vulnerability, e.g., preventing people from building in high hazard areas. One key concept related to areas protected by levees is that of “residual risk”, i.e., the risk from floods greater than the design standard of the levees (levee overtopping), and from levee breach. In this article, we review the legislative framework for regulatory flood maps in the US, France, and Quebec (Canada), compare restrictions on land use within the designated high-hazard zones, and compare how residual risk behind protective structures is taken into account (or not) in regulatory flood maps. Comparing the Flood Insurance Rate Maps (FIRMs) in the USA with the “Plans de Prévention du Risque d’Inondations” (PPRi) in France and the “Cartes de Zones Inondables” in Quebec, we find big differences in how the USA, France and Canada manage residual risk behind the levees.
Considering 3D-objects within a 2D hydraulic modelling approach of pluvial flooding events
(2021) Stork, Matthias; Assmann, André
The production of pluval flood hazard maps have became increasingly important in recent years. In contrast to fluvial flood hazard modelling a more detailed consideration of small surface structures and permeable structures have large relevance for pluvial hazard simulation, because they have a significant influence to runoff processes. Additionally, infrastructure facilities like bridges, tunnels and even large individual buildings are of particular importance, when drainage take place on several height levels which might be connected with each other. Commonly, hydraulic 2D models only allow one level of flow, therefore individual solution approaches have to be developed. Three examples will be elaborated in this paper how model design can meet such requirements in practice. The examples are taken from pluvial flood risk management projects in different regions of Germany, also considering various data availability and quality.
River-dike-floodplain system Interactions and temporal dynamics for large-scale flood risk assessment
(2021) Farrag, Mostafa; Vorogushyn, Sergiy; Nguyen, Dung Viet; Bruijn, Karin de; Merz, Bruno
In a complex network river, hydrodynamic interactions – changes of hydrodynamic characteristics downstream due to upstream effects – play an important role when determining flood hazard and risk. The correct representation of the hydrodynamic interactions is very important for flood modelling and improves our ability to simulate flood extent and inundation depths. The aggregate effect of these interactions on a large-scale catchment highly affects the overall volume of water inundating the floodplain. In this study, the Derived Flood Risk Assessment “DFRA” approach is applied in the Rhine catchment based on the Regional Flood Model (RFM), where two versions of the Regional Inundation Model (RIM) are compared. The two versions are characterized by different routing approaches (piece-wise and continuous routing) and by different cross-section estimation methods. Results show a significant difference between the inundation patterns resulting from the two routing approaches. The continuous routing approach results in less overtopping downstream, while almost no difference is simulated in the upstream part of the network.
Daily and seasonal deformations of a Dutch Levee along a tidal river and during dry and wet conditions.
(2021) Van, Meindert; Hoven, Andre van; Ruyt, Michiel van de
Along the river ‘Hollandse IJssel’ in The Netherlands two infiltration test have been executed. In both situations the levee is infiltrated over a stretch of 30 meters by a maximum overflow of 1.8 l/m/s. Dutch design criteria assume that up to a wave overtopping discharge of 1 l/m/s the infiltration at the polder site of the levee will not significantly influence the level of the phreatic line in the levee. In both test the phreatic line is measured during several hours of overflow and infiltration, as well as some days before and after the experiment. During the test also horizontal and vertical deformations of the slope are measured. Daily and tidal deformations due to low and high tides were measured and show that the dike moves horizontally in the order of 2 to 4 mm during each tidal cycle. During overflow in the second test at the end of a dry summer, the levee also swelled and deformations up to 60 mm were measured. In this paper the two tests, the water pressure and deformation measurements and conclusions are presented.
Degradation of grass revetments: a comparison of field observations and structured expert judgement
(2021) Klerk, Wouter Jan; Adhi, Radityo Andjaringrat
Many flood defences in areas with a mild wave climate and lack of strong currents are covered with a grass revetment, typically on top of an erosion-resistant (clay) layer. The grass revetment increases the erosion-resistance due to its dense root structure, and experimental overtopping and wave impact tests have shown that it significantly increases the resistance to wave impact, run-up and overtopping loads. However, grass is a natural material, and especially when exposed to loads from weather, storms and human influences, assessment of its deterioration rate is difficult. Therefore, a Structured Expert Judgement study was carried out in which experts, mostly dike inspectors, were asked to estimate rates of deterioration for different types of grass revetments. The experts were weighted based on their performance on seed questions. In this paper we compare the results to damage observations in the Rhine delta which have been obtained during routine inspections. From this comparison it is found that degradation rates of grass revetments vary greatly for different locations, which is a probable cause of the considerable variance found from the Structured Expert Judgement study. Using an illustrative case study, we show the implications for inspection and maintenance of grass revetments.
Post-event Flood Damage Surveys: A New Zealand Experience and Implications for Flood Risk Analysis
(2021) Paulik, Ryan; Crowley, Kate; Williams, Shaun
Disaster risk managers are shifting from hazard-centric identification of asset exposure, to quantitative risk assessments based on an understanding of asset vulnerability to impacts. For flood hazard management this shift is support by empirical data detailing the damage reponse of asset typologies when exposed to varying flood hazard intensities. This data is rarely available to reserchers therefore, developing this understanding requires its post-event collection following flood events. This study presents a survey methodology applied to five flood events in New Zealand to develop an empirical residential building damage database for post-hoc vulnerability analysis. Damage data collected is described for building and component attribute susceptibility to damage from exposure to flood inundation depths. Quantity survey guidelines were used during post-hoc analysis to convert observed component damage ratios to asset-level damage ratios. We observe for four strucutral and non-structural building components that internal finishes and service components contributed the most to asset-level damage ratios up to 1.5 m above building floor levels. These detailed component observations coupled with damage ratio estimates for residential building typologies can inform future post-hoc empirical or synthetic methods to develop relative damage curves.
Managing drought effects on levees in England and The Netherlands
(2021) Bottema, Marcel; Gunn, Neil; Haastrecht, Britt van; Vonk, Bart; Hemert, Henk van
Until quite recently, drought-related risks to levees received relatively little attention in The Netherlands and England, despite the fact that hot and dry summer periods became more common since about 1989, with 2003 producing one of the hottest, driest and sunniest summers measured so far. At the end of that 2003 summer, a dried-out peat levee near the Dutch town of Wilnis suddenly gave way. Especially in the first years that followed, drought effects received more attention in management practices, and a significant amount of research on drought and levees was initiated. Fifteen years later, when attention for drought effects had somewhat declined, another drought struck. This 2018 drought was even more severe than the 2003 one. Probably as a result of the improved levee management practices, no (near-)failures occurred during the 2018 drought. Yet there were several cases of deep cracks and significant damage to grass revetments. In this paper, the 2018 drought effects and drought management practices are described for Dutch and English levees, and some common lessons are drawn.
Sentinel data for flood disaster monitoring and assessment: case studies in Romania
(2021) Irimescu, Anisoara; Mihailescu, Denis; Stancalie, Gheorghe
Floods represent one of the most significant natural disaster in Romania. The paper describes the main stages of image processing, for flood disaster monitoring and assessment in radar domain: the processing chain involves the stages starting with image calibration, speckle filtering, segmentation/histogram analysis and terrain corrections. The results of satellite data processing were integrated in a GIS environment to obtain standardized, cartographic products. The satellite-based flood monitoring includes: mapping the maximum flood extent, flooded area classification, flood evolution maps etc., while the damage assessment covers: flooded areas, affected population, categories of land use and communication infrastructure. The paper presents recent flood case studies of March 2018, in the upper part of the Olt basin, located in the central part of Romania, based on Sentinel-1 (S1) satellite imageries and ancillary in-situ data (hydrological and meteorological measurements). The S1 satellite provide high temporal frequency (daily) and good spatial resolution (10-11 m), which have been used as a primary data source for flood disaster monitoring (S1) and damage assessment (Corine Land Cover, 2018). In order to map the flood extent, the Synthetic Aperture Radar (SAR) sensor of S1 is used due to all-weather monitoring capability and its large coverage.
Development of a flood damage model for urban drainage networks
(2021) Gallazzi, Alice; Molinari, Daniela; Ballio, Francesco; Scorzini, Anna Rita
A thorough understanding and assessment of flood damage to network infrastructures is fundamental to assist both policy makers and managing authorities in mitigation and restoration actions against inundations and, consequently, in increasing the resilience of the territories at risk. This research work focuses on the estimation of potential impacts of floods on urban drainage systems, by proposing a general methodology that can be adapted to other typologies of networks. The method consists in the development of damage-dysfunction matrices, as proposed by Eleutério et al. (Nat. Hazards Earth Syst. Sci., 13, 983–998, 2013), for drainage systems, by adopting an expert-based approach. These matrices allow analysing physical, systemic and functional vulnerability of each component of the network under investigation and, therefore, identifying the potential transfer of dysfunctions between the different components. Regarding this last point, a hierarchy description of the network was developed, by means of an ad-hoc methodology, in order to assign a systemic vulnerability degree to each component, hence helping the managing authority to prioritize recovery actions in case of emergency. Nonetheless, by identifying the number and types of users (i.e. residents, businesses, institutions) connected to each sewage pipe, the potential adverse consequences of sewerage’s disruptions for society are investigated as well. As an example, the model has been implemented on the sewerage system in the municipality of Parma, Northern Italy, by using the Baganza River Flood in October 2014 as a case study in support of the work.
How does culture affect individual adaptation to climate-driven floods?
(2021) Noll, Brayton; Filatova, Tatiana; Need, Ariana
Expanding human developments and climate change have exacerbated the impact of natural hazards worldwide. In particular, accelerating flood risks entails that more traditional top down measures are complimented by individual adaptation at the household level. Worldwide, social surveys provide rich information about factors motivating individual adaptation to climate-driven floods. Notably, much of this empirical research has focused on the Global North. Yet, empirical research explicitly measuring whether and how climate change adaptation varies across cultures is lacking. Using Hofstede's Cultural Rankings as a measure of national culture, we utilize meta-regression analysis to investigate the effects of culture on individuals' motivation to adapt to climate-driven floods. This research makes a unique contribution to the literature by providing some of the first empirical evidence on the interaction effects between culture and individual flooding adaptation motivation based on the data collected across a large sample of countries. The results provide strong statistical support for the importance of considering cultural differences when empirically assessing limits of individual adaptation worldwide.
People, not just places: Expanding social vulnerability indices by social-psychological factors
(2021) Babcicky, Philipp; Seebauer, Sebastian
Damage and disruption caused by floods do not just arise from the characteristics of physical structures, but also from the characteristics of residents inhabiting these structures. Social vulnerability studies typically employ socio-demographic proxy indicators that do not address the risk attitudes, beliefs and agency of those living in areas at risk. To close this gap, this paper introduces a range of indicators from psychological risk research. Physical, social and psychological indicators are compared for their influence on vulnerability outcomes such as building damage or emotional distress. Based on survey data of 456 Austrian at-risk households, hierarchical regression models confirm the additional explanatory value of psychological indicators above and beyond physical and social indicators. Adding psychological indicators up to doubles the explained variance in vulnerability outcomes, in particular for health impacts and distress. General intentions for flood preparedness, fear of flooding and self-efficacy are most relevant. For a more holistic view of vulnerability, measurement instruments should incorporate psychological indicators. Disaggregated household-level data is necessary to fully capture the inter-individual differences between households living in the same flood-prone area. Indicators perform differently depending on the other indicators included, and the considered outcome; therefore, we caution against pooling indicators to composite vulnerability indices.
Data integration for rapid flood mapping and impact assessment
(2021) Schröter, Kai; Lüdtke, Stefan; Eggert, Daniel; Kreibich, Heidi; Merz, Bruno
Efficient flood disaster response and recovery need rapid flood mapping and impact assessments. Increasing amounts of data are available in near real-time from a growing diversity of sensors and data sources. Therefore we need to improve our capabilities of extracting and integrating knowledge from heterogeneous data sources. Using the June flood 2013 in Dresden as a use case, this study investigates whether the combination of multiple data sources provides more reliable and more accurate inundation depths maps for rapid flood impact assessments. In this example, we use remote sensing-based flood masks, water level observation and inundation depth-estimates extracted from photos shared in social media streams for inundation mapping. We assess the reliability and accuracy of the inundation maps and compare them with a combined multi-source inundation map as well as an official reference map. The results indicate that the combination of different data sources helps to close gaps in individual data sources. Further, it has a compensatory effect, which results in more reliable and more accurate inundation maps.
Operating and optimising multifunctional urban flood protection - Lake Phoenix Dortmund
(2021) Johann, Georg; Hartung , Alexander
Lake PHOENIX in the heart of the city of Dortmund simultaneously fulfills many functions. In terms of city planning the lake is very significant. First and foremost it serves the local recreation of the citizens. The district of Hörde has been greatly upgraded and nowadays a very attractive construction area exists within the middle of the city. Ecologically, a 24.5-hectare mesotrophic shallow-water lake was created, which is sensitive to organic pollution due to its conditions. Third, this lake also fulfills a flood protection function. The river Emscher bypasses the Lake. Only if discharge is more than a HQ20, the Emscher flows into the lake. Lake PHOENIX offers a flood volume of 235,000 m³ and is able to reduce the flood discharge from HQ20 up to HQ100. During the first years of operation, it became evident that natural succession along the river causes many questions about the dimensioning and operation of the plant. This report describes the results of the intensive measurement campaign and the findings from the renewed. Last but not least, the effects on flood risk management are described and discussed.
Continuuous assessment of the resilience of critical infrastructure: the Nantes ring road flood experimental scenario
(2021) Dolidon, Hélène; Lilas, Lionel; Kamissoko, Daouda
Flooding is frequent on the Nantes ring road and disrupts users dependent on this mode of transport directly or indirectly. To deal with them, the road operator has defined preventive and curative measures based essentially on the flow of the river involved in the submergence of the roadway. The RESIIST (Resilience of Interconnected Infrastructures and Systems) research project aims to develop a methodology and tools to assess the resilience of Critical Infrastructures (within the meaning of European Directive 2008/114/EC), of which we find the ring road. In order to test them, a scenario will be used to simulate the events likely to cause flooding, characterise the disturbances caused by these events and the interactions with adjacent road infrastructures and present a decision aiding based on the road operator's criteria. RESIIST can contribute to improving the resilience of critical infrastructures by enabling stakeholders to continuously monitor data from the context, to interpret them and deduce the disruption’s risks on infrastructure and territory and finally to benefit from proposals for solutions adapted and corresponding to their decision criteria. More modestly, this scenario could serve as a support in discussions on possible work concerning the ring road and the crisis management protocols.
Adaptation pathways and path dependencies: Insights into past and future decision-making in flood risk management
(2021) Clar, Christoph; Hanger-Kopp, Susanne; Schinko, Thomas; Seebauer, Sebastian; Thaler, Thomas
Recent extreme flood events show that the challenges posed by climate-related risks demand well-informed and -prepared local planning and governance. Consequently, the main political and academic discourse revolves around developing approaches that make society more resilient against potential future events not just by introducing smart technical solutions, but also by improving and strengthening local decision-making processes. Nonetheless, flood risk management decisions and their impacts are typically developed as a response to a singular past flood event, often overlooking the locally specific social and economic framework-conditions. Hence, alternative management options are often not considered within the decision-making process, although the decision might have long-term impacts. The paper analyzes the long-term development and impacts of decision-making arenas in which local adaptation policy evolves and assesses the impacts on flood risk management. These arenas are characterized by (1) competing interests from various policy areas, (2) ad-hoc decisions often taking precedence over strategic planning for long-term climate risk management, and (3) previous decisions providing carry-over, follow-up or even creating lock-in effects for later decisions. We propose a novel approach that brings together the broad range of knowledge about path dependencies with ongoing scholarly debates on adaptation pathways in flood risk management. This enables us to combine backwards- with forward-looking perspectives and, thus, both analyze past and support (possible) future decision-making. Our case studies are located in two Austrian climate change adaptation regions. There, we identify intersecting pathways of how hazards and socio-economic conditions developed over time and identify crucial points in time in which major decisions were made. This allows us to trace past pathways that lead to particular constellations and situations in which a specific pathway is chosen over other alternatives. We argue that learning from these past experiences lays the foundation for the development of socioeconomically and politically feasible flood risk management pathways for the future.
Design flood assessment on the upper Rhine using historical data and accounting for discharge uncertainty
(2021) Lang, M.; Le Coz, J.; Renard, B.; Darienzo, M.
Design floods on the upper Rhine River are a major issue for French-German agreements on flood embankments. As intense river training has modified the Rhine River morphology during the 19th century, with a significant rectification of the river course, some disagreement does exist on the interest and value of including information on historical floods. Some hydrological studies are using discharge series from the 20th century only, arguing that it is not possible to estimate flood discharge correctly during and before the river works of the 19th century. Other studies include a set of large historical floods during the 19th century. Unfortunately, design flood estimates with or without historical information are significantly. We used two long discharge series in Basel-Switzerland (1808-2018, with a set of historical floods since 1268) and Maxau-Germany (1815-2018). A preliminary analysis allowed crossing different archive sources, correcting data to account for the main river corrections (1714 and 1890), checking the homogeneity of data and assessing the uncertainty of the stage-discharge relationship. We present a comparative study of design floods with several distributions and several series lengths (a few decades to several centuries). A statistical Bayesian framework allows comparing design floods and the corresponding uncertainties.
Next generation exploration of UK future flood risks: High resolution climate, population and adaptation futures
(2021) Sayers, Paul; Horrrit, M.; Kay, A. L.; Mauz, J.; Carr, S.
Under the Climate Change Act 2008 the UK Government is required to publish a Climate Change Risk Assessment (CCRA) every five years. In response to this requirement future flood risk across the UK is explored here under alternative climate change, population growth and adaptation policies through to the 2080s using an innovative emulation model (the Future Flood Explorer). The analysis highlights significant increases in flood risk with Expected Annual Damages rising from £2bn today to £2.7-3.0bn in the 2080s (depending upon associated population growth) given a 2oC rise in Global Mean Surface Temperature, and rising to £3.5-3.9bn given a 4oC rise. The contribution of climate change, population and individual adaptation measures to future changes in flood risk are, for the first time, disaggregated, providing insight to the most significant drivers and important responses. The results highlight that to manage risk effectively under a 2 or 4oC future, an enhanced whole system approach to adaptation is needed with action required from a broad range of stakeholders, from national level down to individual households and businesses.
A flood resilience observatory in French Polynesia: results and research perspectives from the ILOTS project
(2021) B., Bourlier; Taillandier, F.; Heinzlef, C.; Curt, C.; Davies, N.; Serre, D.
It has been pointed out that the French overseas territories are very concerned by flash floods, but this risk is poorly addressed by the national Government and local authorities. The need to innovate in flood risk management approaches in such areas is explained in particular by the awareness of the lack of consideration of vulnerable territories. This work aims to, first, providing a model to assess the level of resilience of Tahiti and Moorea to flooding. Secondly, it lays the foundations for long-term research with the design of a risk and resilience Information System in the Pacific islands being the start of a future territorial observatory. A first step of our work was to provide some contextual elements as well as perspectives for assessing resilience in the territories of Tahiti and Moorea in French Polynesia. Then, we set up different approaches for assessing resilience and try to operationalise this concept to finally develop a global model adapted to these particular territories.
A method to assess the failure probabilities of river levees based on Elicitation, Calibration, Aggregation, and Debiasing of expert judgement (IeCAD)
(2021) Peyras, Laurent; Carvajal, Claudio; Diab, Youssef; Hathout, Michel; Vuillet, Marc
Studies carried out to analyse the risks of levees must include an evaluation of the probabilities of occurrence of different failure mechanisms (overflow, internal erosion, sliding and scouring). The probabilistic quantitative evaluation of these mechanisms remains difficult due to often insufficient input data, the natural variability of the materials, structures of very long length, the availability of mechanical models for certain failure mechanisms, and the random nature of the stresses involved. This makes it necessary to call for expert judgement to evaluate the probabilities of failure. However, expert judgement is generally associated with a qualitative and subjective dimension, and it comprises biases liable to impair the capacities of an expert to elicit their evaluations. This article proposes an approach to processing expert judgement that includes the modalities of Individual expert Elicitation, Calibration, Aggregation, and Debiasing of expert judgement (IeCAD). This IeCAD approach has been developed for river levees in view to correcting biased expert evaluations in the case of evaluating the failure probability of structures.
Control over one’s environment? Leveling political capabilities to advance procedural justice in Flood Risk Management
(2021) Brackel, Lieke; Pesch, Udo; Doorn, Neelke
Land use change, managed retreat, and relocation programs are examples of exposure reduction measures in Flood Risk Management (FRM). Procedural justice research can help to address inequalities in people’s ability to shape FRM decision-making. Relevant, as ample controversies related to exposure reduction have been documented. In this paper, the concept of political capabilities developed by Holland and Nussbaum is proposed to help better understand and potentially resolve inequalities in FRM decision-making. We propose to understand political capabilities as having sufficient political control over one’s environment. In this way, the analysis can include both actors that have too little as well as those that have too much political influence. This paper further discusses the possibilities and limitations of the concept of political capabilities for FRM. The concept of political capabilities draws attention to the initial stages of FRM politics and is adaptable to different decision-making contexts. Moreover, political capabilities shift the focus from vulnerability to human agency, which also helps to address concerns in the literature about involuntary relocations and the loss of autonomy. The Dutch Room for the River program is proposed as an empirical case to test and develop the political capabilities framework for European Flood Risk Management.
Risk Informed Decisions for Levees
(2021) Austin, Jasmine; Sharp, Michael; Sossenkina, Elena; Vroman, Noah; Simm, Jonathan; Hollingsworth, Claire; Bake, Don de; Labrujere, Astrid; Tourment, Remy; Hahn, Mitchell
Recent events including the establishment of national levee committees in many countries as well as the recent establishment of a Technical Committee on Levees at the International Commission on Large Dams points to the growing interest in levee safety. Additionally, the use of information obtained from risk assessments for levee safety management is becoming more prevalent throughout the world. Several countries are routinely applying this information to support decisions and prioritize actions in all aspects of the life cycle of a levee. An initial effort was given to gather information on the determination of risk related to levees and the application of that risk in making risk management decisions. In November 2018, representatives from Canada (British Columbia), France, Netherlands, United Kingdom, and United States met to discuss risk-informed decisions for levees. During the forum, each country representative shared how risk assessment information is applied to levee management decisions in their respective country. A report of findings from this workshop was presented as an oral presentation at the 2019 ICOLD Conference, and a number of additional countries were queried to expand the existing information. This paper will provide a comprehensive report of information collected from numerous countries on the collection and application of risk information to inform levee management decisions. Preliminary findings suggest that many countries are performing risk assessments but the use of that information to inform decisions is inconsistent and in many instances only using a component of the risk. It is anticipated that the findings from this effort will serve as the impetus for the development of consistent international practices in the management of levee safety.
Impact of climate change on Hungarian Water Management Strategy
(2021) Balatonyi, László
One of the pillars of the Hungarian Water Strategy is preparing for the expected effects of climate change. Changes in the spatial and temporal distribution of water is the major challenge for Hungarian Water Management Service. Hungary is threatened by the phenomenon of water surplus and water scarcity at the same time, and making efforts to overcome all these is not only engineering task. As the impacts of climate change are getting more powerful the situation gets more complicated. The three biggest floods on the Danube happened in the last two decades, whereas on the Tisza four record breaking flood occurred within 36 month around the millennium. The floods of the past 20 years made it clear that extreme floods have to be reckoned with in Hungary. The extremities affecting the economy made the Hungarian water management reforms necessary. The periods of water surplus have resulted in extreme floods in streams over the past 20 years. The increasing flash floods have multiplied local water damages, and the frequency of urban floods has reached unprecedented levels.
Evaluating past and future flood risk reduction in the Rhine river basin
(2021) Schmid-Breton, Adrian; Schulte-Kellinghaus, Nikola
To evaluate the effects of implemented or planned flood risk management measures on risk and damage reduction, the International Commission for the Protection of the Rhine (ICPR) has developed a method and a specific tool named “ICPR FloRiAn (Flood Risk Analysis)”, running in a geographic information system. The instrument, available on demand, was applied by the ICPR to the Rhine but also by external users to other rivers in Europe. The tool uses flood hazard maps (like the so-called ICPR “Rhine Atlas”) and associated recurrence periods for an overall damage and risk assessment for four receptors: human health, environment, cultural heritage and economic activity. Calculations with FloRiAn by the ICPR show that the flood risk reduction target defined in the Action Plan on Floods in 1998 could be achieved with the measures already taken and those planned until 2030. Furthermore, the ICPR launched a new programme in 2020, entitled "Rhine 2040", which sets quantified risk reduction objectives until 2040. The focus of the programme is climate resilience. In the future, it is planned to use FloRiAn again to estimate the reduction of damages and risks caused by new measures.
Investigating ways to predict channel changes to inform flood risk management now and in the future
(2021) Bowman, Hayley; Jeffries, Richard; Ing, Rebecca; Hemsworth, Matthew; Todd-Burley, Natasha; Hankin, Barry; Soar, Philip; Thorne, Colin
Floods can cause severe and rapid changes in rivers. They can erode river banks and deposit vast quantities of sediment. This can impact on land-use, infrastructure (such as bridges and culverts), and properties where flood risk is increased. Understanding these natural processes, and where they are more likely to occur, can inform risk assessment, and identify opportunities to work with nature. Approaches to identify geomorphological actitivity in rivers have been reviewed to determine which could have potential to create a nationwide assessment of river channel change in England and Wales. Two existing approaches and two novel approaches have been tested and validated against fluvial audits to determine how well they identify geomorphological activity. One of the new approaches developed though the research was used to create a national scenario library of erosion maps representing different sediment sizes, channel roughness, and rainfall probabilities. Such information could be used to plan for future change, prioritise channel maintenance activity to locations with greatest risk or opportunity, and deliver sustainable flood risk and environment management.
Flooding impact on bridges and roads: from asset- to network-level
(2021) Arrighi, Chiara; Pregnolato, Maria; Castelli, Fabio
According to UNISDR, floods are the most frequent and damaging natural threat worldwide. Whereas the assessment of direct losses is well advanced, the evaluation of indirect impacts is less frequently applied. Indirect impacts are not due to the physical contact with flood water but result from the reduced performance of infrastructures. Linear critical infrastructures (such as roads and pipes) have an interconnected nature that may lead to failure propagation so that impacts extend far beyond the inundated areas and/or period. This work presents the analysis of two linear infrastructure systems, the water distribution system and the road network system. The evaluation of flood impact on the two networks is carried out for four scenarios, obtained by a coupled 1D-quasi 2D hydraulic model. Two methods are used for assessing the impacts on the water distribution system and on the road network, a Pressure-Driven Demand network model and a transport network disruption model respectively. The analysis is focused on the identification of: (i) impact metrics; (ii) vulnerable elements exposed to the flood; (iii) similarities and differences of the methodological aspects for the two networks. The study presents an application to the city of Florence (Italy).
Post-disaster reorganisation of local and national institutions: the case of St. Martin after hurricane Irma (West Indies)
(2021) Jouannic, Gwenaël; Minh, Chloé Tran Duc; Crozier, Denis
With the concept of "build back better", the United Nations emphasizes the importance of the recovery phase following a natural hazard as an opportunity to implement vulnerability reduction measures. This work here focuses on the ongoing recovery of the French part of island of St. Martin following hurricanes Irma in September 2017. The recovery of this semi-autonomous territory is a major challenge for the local authorities and for the French State. The current state of post-disaster recovery shows the difficulties of reconciling the two imperatives of "rebuild faster" and "rebuild better", in a context of social, political and media pressure. Therefore, what conditions would be necessary to take advantage of this key moment and make the small island more resilient to a new event? What do we learn from this experience for the management of the recovery?
Quantitative assessment of evacuation measures in flood-prone areas
(2021) Kolen, Bas; Dannenberg, Paul; Gelder, Pieter van
Evacuation is a tool to minimize the loss of life and economic damages in flood (threat) scenarios. The Dutch programs ‘Water and Evacuation’ and ‘Wave2020’ focused on the improvement of emergency preparation. Effort has been placed to improve information management, evacuation preparation, decision making and to increase risk awareness among professionals and citizens. The question is however how to incorporate these measures into account in a quantitative risk assessment. In this paper we focus on the improvements of the departure curve by emergency planning. This research method builds on the warning guidebook and a questionnaire developed by the USACE (Mileti and Sorensen 2015) and how evacuation is taken into account in the Dutch flood risk approach (ENW 2017). In a case study the PBL method (Pleijter and Kolen 2016), a macro model to determine evacuation and loss of life is compared to LifeSim, an agent-based models. In this research we concluded that improvements in the departure curve do not result in a significant increase of effectiveness of preventive evacuation in the Netherlands because the (national) road network is already overcrowded. Only when the traffic network has free capacity left an improvement of the departure curve will increase effectiveness of evacuation.
International Handbook for Emergency Response to Flood Risk: A call for collaboration
(2021) Vonk, Bart; Vries, Wout de; Kuijk, Eric van; Bottema, Marcel; Wentholt, Ludolph; Huijskes, Eric
Flood emergency response is an essential component of a flood risk management strategy. Effective flood emergency response depends on implementing the appropriate measures, and on executing them correctly. The skills and expertise of emergency management teams play a crucial role in this response. It is crucial that all involved work along commonly agreed lines. To achieve this, an initiative is launched to arrive at an International Handbook for Emergency Response to Flood Risk. This handbook will provide these “commonly agreed lines”, covering flood emergency response management in general and will include topics such as failure mechanisms, techniques for intervention, logistics and health & safety. It will showcase good practices and will share lessons learnt from flood emergency response approaches all over the world. In this way it will be an invaluable tool to train staff in the operation of flood fighting and to ascertain that the assistance from (international) flood fighting colleagues is at the appropriate level. During the FLOODrisk 2020 Conference, a first framework of this International Handbook is presented and discussed with the participants to ensure the framework meets their needs. We will extend an invitation to participants to provide suggestions and to join forces in this initiative. We are aiming to formalise this initiative towards the end of 2021.
Communication in crisis management – current status, needs and potential development areas
(2021) Jankowska, Karolina; Adamczyk, Andrzej; Gierszal, Henryk
This work aim is to present the communication systems that are currently available on the market and to discuss them regarding their use, shortcomings, potential improvement and development opportunities. It also presents the most important and immediate needs to improve the quality and reliability of the signal to avoid outrages and connection failures. Also, other communication problems are discussed here, such as fake news and terminology-related challenges. Using effective and secure communication system is important during incidents and crisis situations for information exchange and situation awareness for all entities involved in the field and remotely in command centres. Ineffective communication or breakdowns in the information conveying channels are considered to be the most significant reasons for inadequate or failed response to natural disasters such as flooding. In order to evaluate the current status and currently used technologies, needs and potential areas of development a survey has been conducted. As with the warning systems, the most entities use electronic sirens, radio, TV, means of public information. Another way to announce crisis situation is phone, e-mail and specific application such as Nina or MoWaS App. The systems work on various levels: local, regional, national, international and the communication systems vary across countries. For voice communication the most commonly used is public fixed telephone networks and public mobile networks, while for data communication local area network and wireless local area. According to the gathered information, the most common problem regarding communication technologies is the connection itself, which means the signal outrages and interruptions, communication breakdowns, no or poor transfer rate, capacity problems during large scale incidents, no secured non-public communication system, disconnection of fixed and mobile public networks, infrastructure failure (landlines or electricity) etc. The possible innovations opportunities include voice service for group calls and D2D communication on the basis of IP protocol, multimedia Push-to-X services, Mobile Virtual Network Operator (MVNO) for sub-set of services, repeater/relay stations and other. The study was conducted within the DAREnet project which is a network of practitioners dealing with flood resilience in the Danube River Region, supported by a continuously evolving multi-disciplinary community of stakeholders consisting of policy makers, academics, industry and more. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 740750.
BresDefender: A potential emergency measure to prevent or postpone a dike breach.
(2021) Janssen, D.; Schmets, A.J.M.; Hofland, B.; Dado, E.; Jonkman, S.N.
Dikes are designed to withstand a load, with a certain finite probability of occurrence. In case of crises regarding to flood safety, the military is expected to prevent low-laying areas against flooding. Historical attempts show that the effectiveness of emergency measures and strategies are mainly successful caused by the adequate acts of the local people in charge. Based on a literature analysis of breach development, the available time for the application of emergency measures is estimated. This paper introduces the BresDefender strategy, an emergency response strategy, used by the military, to prevent or postpone dike failure. The current BresDefender strategy is a floating pontoon, which can placed on a weakened dike section. It is expected that it can be applied during two scenario’s. In the first scenario, the BresDefender is applied during the early stages of breach formation. In the second scenario, it restores the original crest height, where overflow is expected in the near future e.g. in case of macro instability. The BresDefender is expected to stabilize the weakened dike section.
Enhancing the resilience of levee systems through methodological developments
(2021) Igigabel, Marc; Diab, Youssef; Yates , Marissa
The resilience of levee systems is intuitively associated with physical and technical measures applied to aide in the recovery or adaptation after a destructive event. However, facing a hazard whose characteristics are never fully anticipated and to which a fully predetermined response cannot be proposed, the responsiveness of levee managers depends primarily on their ability to make decisions that must necessarily be based on a sufficient level of information and be supported by appropriate methodological frameworks. Building on previous research about the response to the Xynthia storm, this paper demonstrates that the resilience of protection systems involves expanding the approaches for hazard characterization, flood protection system definition, and intervention modes. With climate change, and the current ecological and digital transitions, methodological developments in the field of flood protection should also encourage the mobilization of more varied disciplines and strengthen solidarity between stakeholders. These links must be woven in the long term, under normal conditions, to be put in place rapidly in emergency situations. Ultimately, methodologies and operational tools must be developed for all (both normal and emergency) circumstances, within the framework of a global, integrated and cohesive approach.
Examining the Operational Aspect of Pedestrian Evacuation Modelling; A case study of Ras-Baalbek flash floods–Lebanon.
(2021) Sarkissian, Rita Der; Abdallah, Chadi; Zaninetti, Jean-Marc; Nedjai, Rachid
A number of evacuation models exist in literature, but investigations of their operational aspects and efficient implementation are rare. The purpose of this paper is to critically assess the operational aspect of pedestrian evacuation models for flash floods mitigation. Through a detailed real-life case study in Ras-Baalbek village-Lebanon, the efficiency of evacuation models when it comes to saving lives was examined. Potential evacuation times were established using an anisotropic least-cost-distance (LCD) approach combined with an exploratory geospatial analysis. The next step was a field verification of the obtained results and accordingly, a detailed evacuation plan that would allow evacuees for a quick departure before flash floods arrival was established. Based on the modeling results, evacuation signs were proposed to be installed on roads along with building vertical-evacuation structures to enhance the evacuation time. The obtained evacuation-modeling outcomes showcased to have multiple operational implications: flood risk outreach, educating and training (preparedness and response), reducing risk and casualties, long-term land use/land cover zoning and, ultimately, improving communities’ resilience to floods.

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