A comparative analysis of the relationship between flood experience and private flood mitigation behaviour in the regions of England

There has been a move towards a more integrated approach to flood risk management, which includes a stronger focus on property level measures. However, in England the uptake of these measures remains low. Flood experience has been found to influence preparedness (i.e. the uptake of measures), but even experience does not always result in an increase in preparedness. We investigate the variations in the relationship between experience and preparedness for the regions of England as defined by the Environment Agency. Analysis of survey data collected by the Environment Agency among the at risk population between 1997 to 2004 was undertaken to determine the differences between the seven regions. We find that in the South West, Southern and Anglian regions increases in preparedness with increasing experience are higher compared to other regions. In the Thames, Midlands and North West regions the preparedness increases less with increasing experience. We explore the influence of other factors influencing flood mitigation behaviour that have been previously found in the literature and find that the differences between regions are correlated with the severity of experienced flooding and whether English is the first language of the respondents

Exploring drought‐to‐flood interactions and dynamics: A global case review

This study synthesizes the current understanding of the hydrological, impact, and adaptation processes underlying drought‐to‐flood events (i.e., consecutive drought and flood events), and how they interact. Based on an analysis of literature and a global assessment of historic cases, we show how drought can affect flood risk and assess under which circumstances drought‐to‐flood interactions can lead to increased or decreased risk. We make a distinction between hydrological, socio‐economic and adaptation processes. Hydrological processes include storage and runoff processes, which both seem to mostly play a role when the drought is a multiyear event and when the flood occurs during the drought. However, which process is dominant when and where, and how this is influenced by human intervention needs further research. Processes related to socio‐economic impacts have been studied less than hydrological processes, but in general, changes in vulnerability seem to play an important role in increasing or decreasing drought‐to‐flood impacts. Additionally, there is evidence of increased water quality problems due to drought‐to‐flood events, when compared to drought or flood events by themselves. Adaptation affects both hydrological (e.g., through groundwater extraction) or socio‐economic (e.g., influencing vulnerability) processes. There are many examples of adaptation, but there is limited evidence of when and where certain processes occur and why. Overall, research on drought‐to‐flood events is scarce. To increase our understanding of drought‐to‐flood events we need more comprehensive studies on the underlying hydrological, socio‐economic, and adaptation processes and their interactions, as well as the circumstances that lead to the dominance of certain processes. This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Extreme

Review article: Drought as a continuum – memory effects in interlinked hydrological, ecological, and social systems

Droughts are often long-lasting phenomena, without a distinct start or end and with impacts cascading across sectors and systems, creating long-term legacies. Nevertheless, our current perceptions and management of droughts and their impacts are often event-based, which can limit the effective assessment of drought risks and reduction of drought impacts. Here, we advocate for changing this perspective and viewing drought as a hydrological–ecological–social continuum. We take a systems theory perspective and focus on how “memory” causes feedback and interactions between parts of the interconnected systems at different timescales. We first discuss the characteristics of the drought continuum with a focus on the hydrological, ecological, and social systems separately, and then we study the system of systems. Our analysis is based on a review of the literature and a study of five cases: Chile, the Colorado River basin in the USA, northeast Brazil, Kenya, and the Rhine River basin in northwest Europe. We find that the memories of past dry and wet periods, carried by both bio-physical (e.g. groundwater, vegetation) and social systems (e.g. people, governance), influence how future drought risk manifests. We identify four archetypes of drought dynamics: impact and recovery, slow resilience building, gradual collapse, and high resilience–big shock. The interactions between the hydrological, ecological, and social systems result in systems shifting between these types, which plays out differently in the five case studies. We call for more research on drought preconditions and recovery in different systems, on dynamics cascading between systems and triggering system changes, and on dynamic vulnerability and maladaptation. Additionally, we advocate for more continuous monitoring of drought hazards and impacts, modelling tools that better incorporate memories and adaptation responses, and management strategies that increase societal and institutional memory. This will help us to better deal with the complex hydrological–ecological–social drought continuum and identify effective pathways to adaptation and mitigation

The challenge of unprecedented floods and droughts in risk management

Risk management has reduced vulnerability to floods and droughts globally1,2, yet their impacts are still increasing3. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change3

Panta Rhei benchmark dataset: socio-hydrological data of paired events of floods and droughts

As the adverse impacts of hydrological extremes increase in many regions of the world, a better understanding of the drivers of changes in risk and impacts is essential for effective flood and drought risk management and climate adaptation. However, there is currently a lack of comprehensive, empirical data about the processes, interactions and feedbacks in complex human-water systems leading to flood and drought impacts. Here we present a benchmark dataset containing socio-hydrological data of paired events, i.e., two floods or two droughts that occurred in the same area. The 45 paired events occurred in 42 different study areas and cover a wide range of socio-economic and hydro-climatic conditions. The dataset is unique in covering both floods and droughts, in the number of cases assessed, and in the quantity of socio-hydrological data. The benchmark dataset comprises: 1) detailed review style reports about the events and key processes between the two events of a pair; 2) the key data table containing variables that assess the indicators which characterise management shortcomings, hazard, exposure, vulnerability and impacts of all events; 3) a table of the indicators-of-change that indicate the differences between the first and second event of a pair. The advantages of the dataset are that it enables comparative analyses across all the paired events based on the indicators-of-change and allows for detailed context- and location-specific assessments based on the extensive data and reports of the individual study areas. The dataset can be used by the scientific community for exploratory data analyses e.g. focused on causal links between risk management, changes in hazard, exposure and vulnerability and flood or drought impacts. The data can also be used for the development, calibration and validation of socio-hydrological models. The dataset is available to the public through the GFZ Data Services (Kreibich et al. 2023, link for review: https://dataservices.gfz-potsdam.de/panmetaworks/review/923c14519deb04f83815ce108b48dd2581d57b90ce069bec9c948361028b8c85/).</p

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.publishedVersio

A comparative analysis of property level flood mitigation behaviour in the regions of England

&amp;lt;p&amp;gt;Even though there has been a move towards a more integrated approach to flood risk management, with a stronger focus on property level measures to reduce flood risk, the uptake of property level measures remains low. Experience has been found to influence the uptake of measures, but even property owners with experience do not always take measures to prepare for future flooding. In this paper we investigate the variations in the relationship between experience and preparedness (i.e. the uptake of property level measures) for the different regions of England. We use survey data collected among the population at risk in the years 1996 to 2004 and perform a hierarchical beta regression to determine the differences between the seven regions. We find that the South West and Southern regions have a higher increase in preparedness with increasing experience compared to other regions. In the Thames, Midlands and North West the preparedness increases less with increasing experience. Based on an analysis of additional data sources (e.g. surveys and maps of structural protection and population) we provide a possible explanation as to why the behaviour of property owners in these regions could be different.&amp;lt;/p&amp;gt; </jats:p

A dynamic framework for flood risk

Long-term feedbacks between humans and floods may lead to complex phenomena such as coping strategies, levee effects, call effects, adaptation effects, and poverty traps. Such phenomena cannot be represented by traditional flood risk approaches that are based on scenarios. Instead, dynamic models of the coupled human-flood interactions are needed. This paper reviews the phenomena, feedbacks and model types associated with this kind of models. The paper concludes that the models may play an important role in integrated flood risk management by exploring a wider range of possible futures, including unexpected phenomena, than is possible when using scenarios.(VLID)4543007Version of recor

A dynamic framework for flood risk

Long-term feedbacks between humans and floods may lead to complex phenomena such as coping strategies, levee effects, call effects, adaptation effects, and poverty traps. Such phenomena cannot be represented by traditional flood risk approaches that are based on scenarios. Instead, dynamic models of the coupled human-flood interactions are needed. This paper reviews the phenomena, feedbacks and model types associated with this kind of models. The paper concludes that the models may play an important role in integrated flood risk management by exploring a wider range of possible futures, including unexpected phenomena, than is possible when using scenarios.Marie Sklodowska-CurieThe ERCThe FW

A Budyko-like framework for exploring the controls of long-term flood risk in coupled human-flood systems

&amp;lt;p&amp;gt;Long term dynamics in human-flood systems differ due to differences in hydrological and societal characteristics. By contrasting and comparing different human-flood systems we increase our understanding of which characteristics lead to which dynamics, which might help to counteract unfavorable developments. We propose a framework for comparing human-flood systems analogous to the Budyko one for traditional catchment hydrology. While in the Budyko framework catchments are classified as either water limited or energy limited, in the framework proposed here the human-flood systems are classified as either hydrology limited or exposure limited. In analogy to the precipitation, potential evapotranspiration and actual evapotranspiration components of the Budyko space we formulate the components of the &amp;amp;#8220;flood risk space&amp;amp;#8221; as hydrological potential loss, manmade potential loss and actual flood loss. The framework is applied to four stylised theoretical systems, investigating how their position in the flood risk space may change under the influence of hydrological, technical and demographic changes. Results show that hydrological changes have the largest effect on a system&amp;amp;#8217;s position in the flood risk space: with an increasing skewness and CV systems become more hydrology limited. The framework&amp;amp;#8217;s value for comparing empirical case studies is demonstrated through an application to two case studies in Germany: Dresden on the Elbe and Cologne on the Rhine. The framework allows us to identify the differences in dynamics between the two case studies, as they are located in different areas of the flood risk space. The difference in dynamics between the Dresden and Cologne systems seems to be mostly caused by the hydrological parameters (i.e. the skewness) rather than the social parameters. The flood frequency distribution is more skewed in the case of the Elbe in Dresden than in the case of the Rhine in Cologne. Therefore, Dresden experiences more shocks to the system (i.e. unexpectedly large floods) than Cologne.&amp;lt;/p&amp;gt;</jats:p