Search

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/).

Risk assessments and disaster management are generally approached from a single-hazard perspective, ignoring the spatial and temporal connections and feedback loops that are involved when consecutive disasters occur. Not only can the total impact of a multi-hazard event differ from the sum of the impacts of the individual events, but the response and recovery process can also be more challenging for multi-hazard events when compared to a single-hazard disaster. Depletion of financial and human resources after a first hazard may for instance increase people’s vulnerability at the time of a second event. This was demonstrated in northern Mozambique, where tropical cyclones Idai and Kenneth made landfall only six weeks apart, early 2019. Despite continued high needs and dependence on humanitarian aid after the second event, UN agencies and partners struggled to provide additional support, due to exhausted stocks and funds after their initial response efforts to Idai. This study (that is part of the MYRIAD-EU project), focuses on post-disaster recovery, which is an often overlooked and misunderstood component of the disaster management cycle. A single-hazard approach to understanding recovery does not sufficiently reflect the complexity that is involved in multi-hazard events due to the potential feedbacks and interactions between hazards and their effects. While several recent studies have made efforts to improve our understanding of the relationships between single natural hazards and the recovery thereafter, recovery dynamics after multi-hazard events are still poorly understood. Additionally, the studies that have looked into recovery after natural disasters are often focussed on a single hazard type or limited set of extreme events in a specific region. To address this knowledge gap, this study sets out to compare economic recovery after multi-hazard events and single-hazard events on a continental scale.Visible Infrared Imaging Radiometer Suite Nighttime Light (VIIRS NTL) data (2013-2022) are used as a proxy for economic recovery. To characterize recovery after different single- and consecutive events, accounting for geological, meteorological, and hydrological hazards, monthly changes in night light intensity are computed. A comparison of the recovery profiles of single- and multi-hazard events will then result in an improved understanding of the different trends and dynamics that are involved with economic recovery after multi-hazard events. The results of this study can be used by policy-makers and aid organizations to improve their disaster management strategies. Moreover, the resulting characterisation of economic recovery after single- and multi-hazard events will support future research into the identification of socio-economic factors that affect the recovery in a multi-hazard context.

Rapid impact assessments immediately after disasters are crucial to enable rapid and effective mobilization of resources for response and recovery efforts. These assessments are often performed by analysing the three components of risk: hazard, exposure and vulnerability. Vulnerability curves are often constructed using historic insurance data or expert judgments, reducing their applicability for the characteristics of the specific hazard and building stock. Therefore, this paper outlines an approach to the creation of event-specific vulnerability curves, using Bayesian statistics (i.e., the zero-one inflated beta distribution) to update a pre-existing vulnerability curve (i.e., the prior) with observed impact data derived from social media. The approach is applied in a case study of Hurricane Dorian, which hit the Bahamas in September 2019. We analysed footage shot predominantly from unmanned aerial vehicles (UAVs) and other airborne vehicles posted on YouTube in the first 10 days after the disaster. Due to its Bayesian nature, the approach can be used regardless of the amount of data available as it balances the contribution of the prior and the observations.

Whilst the last decades have seen a clear shift in emphasis from managing natural hazards to managing risk, the majority of natural-hazard risk research still focuses on single hazards. Internationally, there are calls for more attention for multi-hazards and multi-risks. Within the European Union (EU), the concepts of multi-hazard and multi-risk assessment and management have taken centre stage in recent years. In this perspective paper, we outline several key developments in multi-(hazard-)risk research in the last decade, with a particular focus on the EU. We present challenges for multi-(hazard-)risk management as outlined in several research projects and papers. We then present a research agenda for addressing these challenges. We argue for an approach that addresses multi-(hazard-)risk management through the lens of sustainability challenges that cut across sectors, regions, and hazards. In this approach, the starting point is a specific sustainability challenge, rather than an individual hazard or sector, and trade-offs and synergies are examined across sectors, regions, and hazards. We argue for in-depth case studies in which various approaches for multi-(hazard-)risk management are co-developed and tested in practice. Finally, we present a new pan-European research project in which our proposed research agenda will be implemented, with the goal of enabling stakeholders to develop forward-looking disaster risk management pathways that assess trade-offs and synergies of various strategies across sectors, hazards, and spatial scales.

Reducing the climate change-induced risk of uncontrollable fires in landscapes under nature management, with severe impacts on landscape and society, is particularly urgent in densely-populated and fragmented areas. Reducing fire risk in such areas requires active involvement of a wide diversity of stakeholders. This research letter investigates stakeholders’ needs with regard to fire risk reduction in the Veluwe area in the Netherlands. This densely populated landscape is a popular tourist attraction, and it is one of the most fire-prone landscapes of the Netherlands, with abundant fuels and human ignition sources. We draw upon seven in-depth qualitative interviews with key stakeholders in the Veluwe area, which we situate in a wider review of existing literature. Our analysis demonstrates that the rising incidence of uncontrollable fires poses four types of new challenges to these stakeholders in the Veluwe area. First, stakeholders express the need to reshape existing policy tools and develop novel ones that create synergies between existing policy-priorities (e.g. biodiversity conservation) and fire risk reduction. Second, stakeholders argue for a critical rethinking of the value of landscapes in society, and the diverse roles that fire may play in landscape management research and practice. Third, developing such policy tools requires new modalities and platforms for multi-stakeholder and multi-level collaboration, which are currently lacking because the current and expected future risk of uncontrollable fire is unprecedented. And fourth, the development of effective policy tools requires new knowledge that is interdisciplinary, sensitive towards the local social and ecological characteristics of the area, and which approaches current fire risk challenges and their possible solutions dynamically. While our stakeholder analysis is specific to the Veluwe area in the Netherlands, our findings are also likely to be relevant to other fire-prone nature areas in fragmented landscapes, particularly in Northwestern Europe.

While the last decade saw substantial scientific advances in studies aimed at improving our understanding of natural hazard risk, research and policy commonly address risk from a single-hazard, single-sector perspective. Thus, not considering the spatial and temporal interconnections of these events. Single-hazards risk analyses are often inaccurate and incomplete when multi-hazard disasters occur, as the interaction between them may lead to a different impact than summing the impacts of single events. Therefore, the MYRIAD-EU project aim is to catalyse the paradigm shift required to move towards a multi-risk, multi-sector, systemic approach to risk assessment and management. In order to achieve this, the overall aim is that policy-makers, decision-makers, and practitioners will be able to develop forward-looking disaster risk management pathways that assess trade-offs and synergies across sectors, hazards, and scales. A key first step to achieving this aim is to create a greater understanding of realistic multi-hazard event sets that better examines statistical dependencies between hazard types. To do so, single hazards datasets for meteorological, geological, hydrological and biological events are explored using stochastic modelling and multivariate statistical methods, and create a dataset of potential coinciding hazard events at a global scale. By exploring these multi-hazard interconnections, we achieve a deeper understanding of the different types of multi-hazards events and their temporal and spatial interconnections. Furthermore, this dataset maps indirect, interregional, and cross-sectoral risk throughout the world. Moreover, the multi-hazards event sets will enable to simulate future conditions under climate change by incorporating the Representative Concentration Pathways (RCPs) as well as Socio-economic change using Shared Socioeconomic Pathways (SSPs).

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.

We believe that the transdisciplinary studies on water-related multi-hazards are innovative and critical research by the water community, thus answering the call of the recent Nature Sustainability Editorial ‘Too much and not enough’1 for water science ideas that are not derivative or stagnant. This domain of water studies focuses on the specific contexts where water-related hazardous events occur simultaneously, in cascade or cumulatively with other events. Characteristic of the field is the intensive collaboration of scientists and practitioners from different disciplines working together to better understand, assess and manage water-related multi-hazards. At the recent Asia Oceania Geosciences Society–European Geosciences Union Joint Conference on New Dimensions for Natural Hazards in Asia, we discussed the statement ‘Too much and not enough’1 and here suggest three reasons why transdisciplinary collaborations have led to many new ideas and notable advancements in the field of water-related multi-hazard research in recent years.

The increased complexity of disaster risk due to climate change, expected population growth and the increasing interconnectedness of disaster impacts across communities and economic sectors, require Disaster Risk Reduction (DRR) measures that are better able to address these growing complexities. Especially Disaster Risk Management (DRM) practitioners need to be able to oversee these complexities. Nonetheless, in the traditional risk paradigm, there is a strong focus on single hazards and the risk faced by individual communities and economic sectors. Breaking the Silos is a serious game designed to support various stakeholders (including policy makers, risk managers, researchers) in understanding and managing the complexities of DRR measures in a multi-(hazard) risk setting, thereby moving away from hazard-silo thinking. What sets Breaking the Silos apart from other disaster risk games, is its explicit focus on multi-risk challenges. The game includes different hazard types, intensities, and their interactions, different impact indicators, and (a)synergies between DRR measures. Moreover, the spread of expert knowledge between different participants and the high levels of freedom and randomness in the game design contribute to a realistic game. The game was successfully launched during the World Bank GFDRR’s Understanding Risk 2020 Forum and later played again with the same settings with researchers from the Swiss Federal Institute of Technology (ETH) in Zurich. Before and after playing the games, participants were asked to complete surveys asking them about their perception of the challenges of DRM and whether the game raised their awareness of these challenges. The preliminary findings indicate that Breaking the Silos was found useful by the participants in increasing awareness of the complexities of risk.

Reliable information on building stock and its vulnerability is important for understanding societal exposure to floods. Unfortunately, developing countries have less access to and availability of this information. Therefore, calculations for flood damage assessments have to use the scarce information available, often aggregated on a national or district level. This study aims to improve current assessments of flood damage by extracting individual structural building characteristics and estimate damage based on the buildings' vulnerability. We carry out an Object-Based Image Analysis (OBIA) of high-resolution (11 cm ground sample distance) Unmanned Aerial Vehicle (UAV) imagery to outline shapes. We then use a Support Vector Machine Learning algorithm to classify the delineated buildings. We combine this information with local depth-damage curves to estimate the economic damages for three villages affected by the 2019 January river floods in the Southern Shire basin in Malawi, and compare this to a conventional approach using land use to denote exposure. The flood extent is obtained from satellite imagery (Sentinel-1), and corresponding water depths determined by combining this with elevation data. The estimated damages from the OBIA and aggregated land-use approach yield €10,140 and €15,782, respectively, highlighting the potential for detailed and local damage assessments using UAV imagery.