Collaborative research to support transition towards integrating flood risk management in urban development

New flood risk management policies account for climate and socio-economic change by embracing a more integrated approach. Their implementation processes require: collaboration between a group of stakeholders; combining objectives and funding from various policy domains; consideration of a range of possible options at all spatial scale levels and for various time horizons. Literature provides limited guidance on how to organise a collaborative planning process to devise integrated flood risk management (IFRM) plans. This paper presents a case study where a recently developed framework for process design and management has been used and evaluates whether or not the collaborative planning process led to an IFRM plan. The case study is Dordrecht (NL) where the new multi-layer-safety (MLS) approach has been applied in the context of the Delta Programme. The Delta Programme investigates how the Netherlands can adapt to the effects of climate change. MLS comprises three flood safety layers to reduce flood risk: flood protection, spatial planning, and emergency response. The framework has been shown to be effective in the delivery of an IFRM plan, it has been enriched by defining the interfaces between and phasing of planning activities, and can be further improved to better guide implementation and governance activities.

Despite an increasing number of people exposed to flood risks in Europe, flood risk perception remains low and effective flood risk management policies are rarely implemented. It becomes increasingly important to understand how local governments can design effective flood risk management policies to address flood risks. In this article, we study whether high flood exposure and flood risk perception correlate with the demand for a specific design of flood risk management policies. We take the ideal case of Switzerland and analyze flood risk management portfolios in 18 flood-prone municipalities along the Aare River. We introduce a novel combination of risk analysis and public policy data: we analyze correlations between recorded flood exposure data and survey data on flood risk perception and policy preferences for selected flood risk management measures. Our results indicate that local governments with high flood risk perception tend to prefer non-structural measures, such as spatial planning and ecological river restoration, to infrastructure measures. In contrast, flood exposure is neither linked to flood risk perception nor to policy preferences. We conclude that flood risk perception is key: it can decisively affect local governments’ preferences to implement specific diversified policy portfolios including more preventive or integrated flood risk management measures. These findings imply that local governments in flood-prone areas should invest in raising their population’s awareness capacity of flood risks and keep it high during periods without flooding.

The flooding system includes the physical process of flooding, the inhabitants of floodplains, their infrastructures and ecosystems, and the people and organizations in the public and private sector that influence or are subject to flooding and its impacts. Flooding systems are continuously changing because of natural and socioeconomic processes, as well as activities that are intended to reduce flood risk. Flood risk management is the process of data and information gathering, risk assessment, appraisal of options, and making, implementing, and reviewing decisions to reduce, control, accept, or redistribute risks of flooding. Integrated flood risk management explicitly recognizes the interrelationships between all risk management measures, and their analysis, costs, and effectiveness, within changing social, economic, and environmental contexts. It can be helped by improving access to data and models, sharing and communicating risk analyses, involving a wider range of stakeholders, and coordinating risk management actions. Flood risk management in England and Wales is rapidly changing. This paper explains these changes in terms of their contribution to integrated flood risk management and describes further developments that are required to enable the difficult task of integrated flood risk management to be realized in practice.

Flood resilience is increasingly discussed in academia and practice as a complement to existing flood risk management approaches (Fekete, Hartmann, & Jüpner 2020). It is seen as a promising concept to deal with increasingly severe consequences of climate change in general, and with increasing flood risk in particular. The debate on flood resilience is linked to the paradigm shift from flood protection to risk management, which started in Europe after the major river flood events in 1993 and 1995 along the river Rhine (Hartmann, 2012), and has developed over the past decades—pushed by further major fluvial and pluvial flood events (Begum, Stive, & Hall, 2007; Hartmann & Juepner, 2014; Klijn, Samuels, & van Os, 2008; Patt & Jüpner, 2020). However, in flood risk management, the academic debate on resilience is only in its infancy (Jüpner et al., 2018; Vis, Klijn, Bruijn, & Buuren, 2003). Many different definitions exist (Disse, Johnson, Leandro, & Hartmann, 2020). Especially when it comes to specific implementation of resilience, the vagueness of the concept—which is sometimes described as one of its strengths (Baggio, Brown, & Hellebrandt, 2015; Brand & Jax, 2007)—can present a problem. How to design a resilient hydraulic infrastructure? This question has not only technical but also concerned with financial and legal aspects. This becomes more complicated when individual protection measures are put in a context of a larger system, such as a city or a region. When and how is a system such as a city or a region resilient, and how does one measure resilience? These questions are important, not only for construction but also for legal (such as liabilities), financial (budgetary), and political reasons. In other words, resilience is not (yet) a ready-to-use concept in flood risk management. Resilience challenges presumptions of traditional flood risk management in many ways. Resilience implies that more and different stakeholders and actors will be involved in flood risk management than before, such as landowners or spatial planners. Hitherto, flood risk management has been and still is mainly the domain of water management (Hartmann & Driessen, 2017), although the prevalence of the traditional civil engineering approach has been questioned before (van den Brink, 2009). This change is not positive for all actors—affected homeowners, but also city planners or mayors now must deal with questions that were previously outside of their realm of competence and responsibility. From a flood risk management perspective, many questions arise, such as: How does resilience add to and change the existing flood risk management system? How can resilience contribute to a more effective and efficient flood risk management approach? What are the specific advantages of integrating resilience in flood risk management? How can resilience be measured and quantified? Which parameters are most relevant? This special collection brings together contributions from different disciplines that address the specific challenges of implementing resilience in flood risk management. The special collection takes the European debate as a starting point. The European Floods Directive from 2007 (2007/EC/60) pushed the debate on flood risk management and resilience in Europe. This Directive established a legal frame on how countries in the European Union have to deal with flood risk for the first time (Hartmann & Jüpner, 2014). At the same time, the shift toward a risk-based approach raised questions such as "what can happen?" "what must not happen?" and "which security level can be realized at which costs?" Ultimately, flood risk management replaces the paradigm of complete protection against floods with the idea of managing the risk (Grünewald, 2005). This makes approaches to resilience and the reduction of damage potential (vulnerabilities)—not only for river floods but also for pluvial rainfall—important. The first three papers in this collection highlight the necessity and consequences of defining the concept of resilience. In their opinion paper, Fekete, Hartmann, and Jüpner (2020) point out that resilience is indeed a trend that neither can nor should be ignored in flood risk management, rather than it should be embraced—with a caveat: the concept is still not exactly defined and cannot be understood as a panacea for all shortcomings and challenges of flood risk management. So, is resilience merely a new buzzword? Dewulf et al. (2019) discuss the power and impact of defining resilience and therewith unravel the political-normative notion of flood resilience as a concept. This illustrates that, with flood resilience, flood risk management turns much more strongly towards social and political science than ever before. Discussing resilience and its definition is thus a crucial step toward successfully implementing it in flood risk management. In her advanced review, Rodina (2019) reveals different notions of resilience in different disciplines when taking on a broader view of the concept (i.e., not solely focusing on flood risks). She concludes that participation and stakeholder involvement are important components of resilience—a theme that is picked up in the next section of this special collection as well. So, though this article had not been part of the original set-up of the special collection, the conclusions are highly relevant for implementing flood resilience in flood risk management. Resilience requires more action by homeowners and citizens. All papers in this section of this special collection leave no doubt about that. Snel, Witte, Hartmann, and Geertman (2020), however, start with a very critical point of departure, namely that many publications on homeowner and citizen involvement do not seem to question if this involvement is necessary. The paper unravels the arguments that are prevalent in the academic debate for more involvement of homeowners in flood resilience, which supposedly comes along with a shift towards flood governance. Four types of main arguments are identified and discussed in the paper. Kuhlicke and the multidisciplinary team of authors writing on the behavioral turn in flood risk management (Kuhlicke et al., 2020) discuss in detail three underlying assumptions of increased involvement of citizens in flood risk management: the motivations of citizens, the effectiveness of measures, and capacities of citizens. In this vein, Rufat et al. (2020) discuss in their opinion paper need for a more nuanced debate on the link between flood risk perception and risk-mitigating behavior. Attems, Thaler, Genovese, and Fuchs (2020) then provide an overview of the measures that homeowners can take to enhance resilience by using property-level flood risk adaptation (PLFRA) measures. The paper confirms that such measures can indeed be an appropriate addition or complement to flood risk management. The third group of papers in this special collection addresses the issue of measuring and communicating resilience. The need for this comes not only from hydraulic engineering but also from the need to communicate about flood risk with homeowners and citizens, as they have to become more involved (as the earlier papers in this special collection clearly show). Pohl (2020) views resilience from a hydrological as well as a hydraulic engineering perspective and outlines what it means to include the concept in flood risk management. In particular, the contribution points out the difficulties of embedding resilience as a design criterion in hydraulic structures. Pohl concludes that—though the fuzziness of resilience is appreciated by some social scientists as a "boundary concept" (Baggio et al., 2015)—hydraulic engineering and hydrology inevitably require some quantifiable measurement of resilience. Fekete (2019) elaborates in his paper how cascading effects and critical infrastructure matter for flood resilience. It thereby shows how flood resilience with this perspective extends existing flood risk management approaches. Cascading effects of critical infrastructure can substantially affect the measurement of flood resilience. Schmitt and Scheid (2020) discuss the need for better risk communication and discuss approaches by focusing on pluvial floods. In particular, they show how a rainstorm severity index may supersede the communicative capacity of statistical rainfall parameters in the communication with nonexperts especially. In conclusion, the contributions in this special collection show how the concept of resilience is advancing flood risk management but also point out some crucial changes and challenges that flood resilience as a concept brings to the practical implementation of flood risk management. It seems inevitable that homeowners especially will play a much more fundamental role in flood resilience, which raises needs for measuring and communication of flood resilience. Along with this shift in flood risk management, the papers illustrate that flood resilience puts flood risk management in a hitherto unknown domain for many water managers, as flood resilience means embracing social and political science. Embedding flood resilience into flood risk management becomes a balancing act—on the one hand, resilience is a political and normative concept, but on the other hand, it needs to be implemented with concrete steps designed via civil engineering and hydrology. This tension is still unsolved and remains a dilemma in implementing flood resilience.

Since the European Parliament adopted its ‘Directive on the Assessment and Management of Flood Risks’, river basin and flood risk management plans have been subject to Strategic Environmental Assessment (SEA). This paper presents the landscape planning methods that were applied to support a flood risk management plan with SEA. It includes proposals for multifunctional flood management measures and the design and assessment of ‘Strategic Alternatives’ (STA). Every STA consists of sets of different measures that help manage floods effectively up to 100-year rainfall events. A GIS-based method was developed to enable flexible production and assessment of STA. 3D visualisations were also produced with GIS, and were mainly applied to support communication during stakeholder involvement. Results are discussed with reference to technical aspects and the importance of providing appropriate information to support decision-making. Theoretical considerations include discussions on landscape planning models and on the role of landscape planning within the new European planning system. Integrative qualities of landscape planning are highlighted, for example in designing new landscapes in cooperation with managers of flood risk. Future research direction includes landscape monitoring, and communicative landscape planning that contributes to strengthening democratic decision making on a regional scale.

Floods are among the most costly natural hazards that affect Europe and Germany, demanding a continuous adaptation of flood risk management. While social and economic development in recent years altered the flood risk patterns mainly with regard to an increase in flood exposure, different flood events are further expected to increase in frequency and severity in certain European regions due to climate change. As a result of recent major flood events in Germany, the German flood risk management shifted to more integrated approaches that include private precaution and preparation to reduce the damage on exposed assets. Yet, detailed insights into the preparedness decisions of flood-prone households remain scarce, especially in connection to mental impacts and individual coping strategies after being affected by different flood types. This thesis aims to gain insights into flash floods as a costly hazard in certain German regions and compares the damage driving factors to the damage driving factors of river floods. Furthermore, psychological impacts as well as the effects on coping and mitigation behaviour of flood-affected households are assessed. In this context, psychological models such as the Protection Motivation Theory (PMT) and methods such as regressions and Bayesian statistics are used to evaluate influencing factors on the mental coping after an event and to identify psychological variables that are connected to intended private flood mitigation. The database consists of surveys that were conducted among affected households after major river floods in 2013 and flash floods in 2016. The main conclusions that can be drawn from this thesis reveal that the damage patterns and damage driving factors of strong flash floods differ significantly from those of river floods due to a rapid flow origination process, higher flow velocities and flow forces. However, the effects on mental coping of people that have been affected by flood events appear to be weakly influenced by different flood types, but yet show a coherence to the event severity, where often thinking of the respective event is pronounced and also connected to a higher mitigation motivation. The mental coping and preparation after floods is further influenced by a good information provision and a social environment, which encourages a positive attitude towards private mitigation. As an overall recommendation, approaches for an integrated flood risk management in Germany should be followed that also take flash floods into account and consider psychological characteristics of affected households to support and promote private flood mitigation. Targeted information campaigns that concern coping options and discuss current flood risks are important to better prepare for future flood hazards in Germany.

Human activities have a profound impact on climate and hydrological processes, contributing to changes in the frequency and severity of hydrological extremes and, consequently, growing socioeconomic vulnerability [1]. Rising sea levels, continuous urban development in low-lying coastal areas, and corresponding changes in flood risk have resulted in devastating flood impacts. Different Flood Risk Management (FRM) strategies have been adopted in various socioeconomic contexts and spatiotemporal scales, the most prevalent being structural protection. In recent years, numerous scholars have raised concerns about this approach, as studies have shown that increasing protection levels can increase socioeconomic vulnerabilities e.g., [2]. FRM strategies alter the dynamics of risk manifested in sociohydrological systems, which must be disentangled to avoid unintended consequences.In the “Cities and rising sea levels” project, scientists from different research disciplines, including hydrology, architecture, landscape architecture, and urban planning, collaborate to tackle these challenges. Combining multidisciplinary knowledge has been central to exploring the cross-sectoral processes involved in FRM. In the present study, we focused on (1) uncovering the cascading effects, including unintended consequences of FRM, as well as (2) highlighting the potentials for holistic assessments of FRM strategies.Our methods include the development of a Causal Loop Diagram (CLD) model describing critical sociohydrological processes of coastal cities operating at different spatial and temporal scales. We identified dynamic feedbacks between (1) flood risk, urban development and economic wealth, (2) flood risk, urban development and social equity, and (3) flood risk, trust in authorities, and institutional capacity, among others. . Based on the CLD, we analyzed key feedback mechanisms and their manifestation in theory and practice. Further, we explored the impacts of different FRM strategies on these feedback mechanisms to uncover differences in impacts on socioeconomic vulnerabilities and wider cross-sectoral impacts. The presentation will present and explore the conceptual model through semiquantitative analyses (Fuzzy Cognitive Maps (FCMs)) and spatiotemporal assessments using a specific case study. We aim at (1) getting case-specific insights into the dynamics produced by the local interplay of flooding events and socioeconomic processes influencing vulnerabilities, and (2) suggesting pathways for new integrated ways of FRM.

Governance in support of integrated flood risk management? The case of Romania

After severe flash floods that caused many fatalities a few years ago in the Mediterranean regions of France, the French government decided to help local authorities to reduce flood risk. Through the example of small basins in southern France, this paper shows the principles and the practises involved in mitigating flood risk. The flood risk management plans, established by river basin authorities, are subsidized both by the central government and by local authorities. They illustrate the progressive change of philosophy in flood management policy. The principles of flood risk management have changed through history from structural measures (dikes, embankments, dams) to non-structural methods (e.g., land-use planning, preparedness measures, reduction of vulnerability, early-warning systems, human collective memory and public awareness). The flood risk management policies are thus politically and technically integrated. This paper points out some of the reasons that can explain the success or the failure of flood risk reduction in a river basin. It shows how partisan politics can be an obstacle to the implementation of such plans. The last challenge is to evaluate the positive and negative effects of the flood-mitigation policies. This work finishes by proposing some indicators to evaluate the real effects of flood reduction.

Flooding is one of the most significant issues facing the UK and Europe. New approaches are being sought to mitigate its impacts, and distributed, catchment-based techniques are becoming increasingly popular. These employ a range of measures, often working with the catchment’s natural processes, in order to improve flood resilience. There remains a lack of conclusive evidence, however, for the impacts of these approaches on the storm runoff, leading to considerable uncertainty in their effectiveness in terms of mitigating flood risk. A new modelling framework for design, assessment, and uncertainty estimation of such distributed, nature-based schemes is developed. An implementation of a semidistributed runoff model demonstrates robustness to spatio-temporal discretisation. Alongside a new hydraulic routing scheme, the model is used to evaluate the impacts on flood risk of in-channel measures applied within an 29 km2 agricultural catchment. Maximum additional channel storage of 70,000 m3 and a corresponding reduction of 11% in peak flows is seen. This, however, would not have been insufficient to prevent flooding in the event considered. Further modifications allow simulation of the impacts of wider measures employing natural processes. This is applied within an uncertainty estimation framework across the headwaters of three mixed-use catchments, ranging in size from 57 km2 to 200km2 , across a series of extreme storm events. A novel surface routing algorithm allows simulation of large arrays distributed features that intercept and store fast runoff. The effect of the measures can be seen across even the most extreme events, with a reduction of up to 15% in the largest peak, albeit that this large impact was associated with a low confidence level. The methodology can reflect the uncertainty in application of natural flood risk management with a poor or incomplete evidence base. The modelling results demonstrate the importance of antecedent conditions and of the timings and magnitudes of a series of storm events. The results shows the benefits of maximizing features’ storage utilisation by allowing a degree of “leakiness” to enable drain-down between storms. An unanticipated result was that some configurations of measures could synchronise previously asynchronous subcatchment flood waves and have a detrimental effect on the flood risk. The framework shows its utility in both modelling and evaluation of catchment-based flood risk management and in wider applications where computational efficiency and uncertainty estimation are important.

Learning for improvement

In response to the extreme flood events of recent decades, the European Floods Directive (2007/60/EC) requires Member States of the European Union to develop Flood Risk Management Plans (Dworak & Gorlach 2005). These plans need to be in place by 2015 and set‘appropriate objectives for the management of flood risk and [reduce] potential adverse consequences of flooding for human health, the environment, cultural heritage and economic activity’ (Floods Directive 2007: Article 7 II). They are based on river basin districts. This special issue addresses the new plan instrument that is unique in terms of its governance since it formally changes flood risk management from being predominantly the responsibility of water engineering, to incorporate spatial planning in the management process.

This article explores the impacts of floods on the economy, environment, and society and tries to clarify the rural community’s coping mechanism to flood disasters in Central Viet Nam. It focuses on the social aspects of flood risk perception that shapes the responses to floods. The research findings revealed that flooding is an essential element for a coastal population, whose livelihood depend on productive functions of cyclical floods. The findings also revealed that floods, causing losses and damages, often inhibited economic development. The surveyed communities appeared to have evolved coping mechanisms to reduce the negative impacts of the floods, yet these coping mechanisms are under pressure due to environmental degradation. Integrated flood risk management is considered as a suitable paradigm for coping with flood disasters.

Characterizing flood risk perception in urban communities of Pakistan

The European Flood Directive (FD) shifted water management policy from flood protection to flood risk management. To facilitate the shift, a new instrument was introduced called the flood risk management plan. According to the FD, a flood risk management plan shall first take into account relevant aspects from water management, nature conservation, land use, spatial planning, navigation, and port infrastructure. Second, the flood risk management plan will be coordinated at the river basin level. This changes the spatial scope of water management compared to (old) flood protection approach and affects a broader group of stakeholder interests, namely landowners behind dikes. As a result, water management has to introduce a governance approach that facilitates stakeholder involvement in which different spatial interests are balanced, bargained and negotiated. Academic governance literature consists mostly of qualitative case studies, because of their complex nature. As a result, most governance literature operates on assumptions which make it difficult to formulate governance strategies that work based on general patterns. To contribute towards scientific methodologies for comparative research a quantitative method was developed to measure satisfaction in a stakeholder process. The method first provides new insights on the relation between interactive governance processes and the procedural satisfaction of stakeholders. Second, it provides insights that help to improve interactive governance in terms of managing a stakeholder process in such a way that greater procedural satisfaction can be achieved.