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Flood inundation models enable us to make hazard predictions for floodplains, mitigating increasing flood fatalities and losses. This book provides an understanding of hydraulic modelling and floodplain dynamics, with a key focus on state-of-the-art remote sensing data, and methods to estimate and communicate uncertainty. Academic researchers in the fields of hydrology, climate change, environmental science and natural hazards, and professionals and policy-makers working in flood risk mitigation, hydraulic engineering and remote sensing will find this an invaluable resource. This volume is the third in a collection of four books on flood disaster management theory and practice within the context of anthropogenic climate change. The others are: Floods in a Changing Climate: Extreme Precipitation by Ramesh Teegavarapu, Floods in a Changing Climate: Hydrological Modeling by P. P. Mujumdar and D. Nagesh Kumar and Floods in a Changing Climate: Risk Management by Slodoban Simonović

Background:The success of vaccination campaigns against COVID-19 infection is vital for moving from a COVID-19 pandemic to an endemic scenario. We aimed to unravel the influence of the risk perception of epidemics along with individual and contextual factors on adherence to COVID-19 vaccination campaigns in Italy and Sweden. Methods:We compared the results of two nationwide surveys carried out in August 2021 across four domains of epidemic risk perception: perceived likelihood, perceived impact on the individual and perceived individual and authority knowledge. The roles of individual and contextual determinants were also explored. Results:The survey included 2144 participants in Sweden (52.3% women) and 2010 in Italy (52.6% women). In both countries, we found that trust in authorities was one of the main drivers of this process, with two-fold increased odds of being vaccinated. Being highly educated and having a higher relative income were associated with a higher adherence to the vaccination campaign (for relative income OR = 1.44, 95% CI 1.23–1.67 in Sweden and OR = 1.18, 95% CI 1.04–1.34 in Italy; for education OR = 1.90, 95% CI 1.30–2.77 in Sweden and OR = 1.47, 95% CI 1.09–1.97 in Italy), whereas a right and centre-right compared with a left and centre-left political orientation was negatively related to vaccination adherence (OR = 0.41, 95% CI 0.25–0.67 in Sweden and OR = 0.47, 95% CI 0.33–0.68 in Italy). Conclusions:Increasing trust in authorities, along with an equal global distribution of vaccine doses, can contribute to accelerating vaccination campaigns around the world and, in turn, to move towards an endemic scenario.

Front Cover -- Hydro-Meteorological Hazards, Risks, and Disasters -- Hydro-Meteorological Hazards, Risks, and Disasters -- Copyright -- Contents -- List of contributors -- I - Floods -- 1 - Flood processes and hazards -- 1.1 Introduction -- 1.2 Flood types and their processes -- 1.2.1 River floods -- 1.2.2 Flash floods -- 1.2.3 Dam-break floods -- 1.2.4 Ice-jam floods -- 1.2.5 Glacial-lake floods -- 1.2.6 Urban floods -- 1.2.7 Coastal floods -- 1.2.8 Hurricane-related floods -- 1.3 Flood hazard probabilities -- 1.4 Floods in a changing world -- References -- 2 - Paleoflood hydrology: reconstructing rare events and extreme flood discharges -- 2.1 Introduction -- 2.2 Paleoflood approaches and methodology -- 2.3 Geological and botanical paleoflood data -- 2.3.1 Sedimentological indicators -- 2.3.2 Botanical-based evidence -- 2.3.2.1 Flood reconstruction based on tree-ring analyses -- 2.3.2.2 Flood reconstruction based on lichenometry -- 2.4 Dating paleoflood evidence -- 2.5 Paleoflood discharge estimation -- 2.6 Flood frequency analysis using paleoflood data -- 2.7 Estimation of paleoflood volume -- 2.8 Applied paleoflood hydrology -- 2.8.1 Paleofloods as an analog of present and future flood disasters -- 2.8.2 Paleoflood hydrology applied to the design of sensitive infrastructures -- 2.8.3 Flood hazards in the context of climate change -- 2.8.4 Floodwater recharge by extreme floods -- 2.9 Conclusions -- Acknowledgments -- References -- 3 - Global and low-cost topographic data to support flood studies -- 3.1 Introduction -- 3.1.1 Growing availability of global earth observation data -- 3.1.2 Recent progress on evaluation of global topographic data in supporting flood modeling -- 3.1.3 Uncertainties in inundation modeling and probabilistic flood mapping -- 3.1.4 Different types of data in constraining uncertainty in flood modeling.

Human activities have increasingly intensified the severity, frequency and negative impacts of droughts in several regions across the world. This trend has led to broader scientific conceptualisations of drought risk that account for human actions and their interplays with natural systems. This review focuses on physical and engineering sciences to examine the way and extent to which these disciplines account for social processes in relation to the production and distribution of drought risk. We conclude that this research has significantly progressed in terms of recognizing the role of humans in reshaping drought risk and its socio-environmental impacts. We note an increasing engagement with and contribution to understanding vulnerability, resilience and adaptation patterns. Moreover, by advancing (socio)hydrological models, developing numerical indexes and enhancing data processing, physical and engineering scientists have determined the extent of human influences in the propagation of drought hazard. However, these studies do not fully capture the complexities of anthropogenic transformations. Very often, they portray society as homogeneous, and decision-making processes as apolitical, thereby concealing the power relations underlying the production of drought and the uneven distribution of its impacts. The resistance in engaging explicitly with politics and social power—despite their major role in producing anthropogenic drought—can be attributed to the strong influence of positivist epistemologies in engineering and physical sciences. We suggest that an active engagement with critical social sciences can further theorisations of drought risk by shedding light on the structural and historical systems of power that engender every socio-environmental transformation.

Abstract. Riverine flood risk studies often require the identification of areas prone
to potential flooding. This modelling process can be based on either
(hydrologically derived) flood hazard maps or (topography-based)
hydrogeomorphic floodplain maps. In this paper, we derive and compare
riverine flood exposure from three global products: a hydrogeomorphic
floodplain map (GFPLAIN250m, hereinafter GFPLAIN) and two flood hazard maps (Flood Hazard Map of the World by the European Commission's Joint Research Centre, hereinafter JRC, and the flood hazard maps produced for
the Global Assessment Report on Disaster Risk Reduction 2015, hereinafter GAR). We find an average spatial agreement between these maps of around 30 % at the river basin level on a global scale. This agreement is highly variable across model combinations and geographic conditions, influenced by climatic humidity, river volume, topography, and coastal proximity. Contrary to expectations, the agreement between the two flood hazard maps is lower compared to their agreement with the hydrogeomorphic floodplain map. We also map riverine flood exposure for 26 countries across the global south by intersecting these maps with three human population maps (Global Human Settlement population grid, hereinafter GHS; High Resolution Settlement Layer, hereinafter HRSL; and WorldPop). The findings of this study indicate that hydrogeomorphic floodplain maps can be a valuable way of producing high-resolution maps of flood-prone zones to support riverine flood risk studies, but caution should be taken in regions that are dry, steep, very flat, or near the coast.

Abstract. Scholars have unravelled the complexities and underlying uncertainties in coupled human and water systems in various fields and disciplines. These complexities, however, are not always reflected in the way in which the dynamics of human–water systems are modelled. One reason is the lack of social data time series, which may be provided by longitudinal surveys. Here, we show the value of collecting longitudinal survey data to enrich sociohydrological modelling of flood risk. To illustrate, we compare and contrast two different approaches (repeated cross-sectional and panel) for collecting longitudinal data and explore changes in flood risk awareness and preparedness in a municipality hit by a flash flood in 2018. We found that risk awareness has not changed significantly in the timeframe under study (1 year). Perceived preparedness increased only among those respondents who suffered low damage during the flood event. We also found gender differences across both approaches for most of the variables explored. Lastly, we argue that results that are consistent across the two approaches can be used for the parametrisation of sociohydrological models. We posit that there is a need to enhance the representation of socio-demographic heterogeneity in modelling human–water systems in order to better support risk management.

Human activities have increasingly intensified the severity, frequency, and negative impacts of droughts in several regions across the world. This trend has led to broader scientific conceptualizations of drought risk that account for human actions and their interplays with natural systems. This review focuses on physical and engineering sciences to examine the way and extent to which these disciplines account for social processes in relation to the production and distribution of drought risk. We conclude that this research has significantly progressed in terms of recognizing the role of humans in reshaping drought risk and its socioenvironmental impacts. We note an increasing engagement with and contribution to understanding vulnerability, resilience, and adaptation patterns. Moreover, by advancing (socio)hydrological models, developing numerical indexes, and enhancing data processing, physical and engineering scientists have determined the extent of human influences in the propagation of drought hazard. However, these studies do not fully capture the complexities of anthropogenic transformations. Very often, they portray society as homogeneous, and decision‐making processes as apolitical, thereby concealing the power relations underlying the production of drought and the uneven distribution of its impacts. The resistance in engaging explicitly with politics and social power—despite their major role in producing anthropogenic drought—can be attributed to the strong influence of positivist epistemologies in engineering and physical sciences. We suggest that an active engagement with critical social sciences can further theorizations of drought risk by shedding light on the structural and historical systems of power that engender every socioenvironmental transformation.

Sociohydrology has advanced understandings of water related phenomena by conceptualizing changes in hydrological flows and risks as the result of the interplay between water and society. However, social power and the heterogeneity of human societies, which are crucial to unravel the feedback mechanisms underlying human-water systems, have not been sufficiently considered. In response, this paper proposes an interdisciplinary approach that draws on political ecology perspectives to combine sociohydrological insights with analyses of social power and of the ways in which different social groups distinctively interact with water systems. We draw on empirical evidence of Cape Town's water insecurity before and during the prolonged drought (2015-2017) that escalated into a severe water crisis, also known as Day Zero. The study integrates times series of reservoir storage and water consumption with 40 interviews and focus group discussions to firstly retrace the historical legacy of Colonial rules, Apartheid and, more recently, neoliberal policies. Within this human-water system, we show how Cape Town's political legacy has encouraged unsustainable levels of water consumption amongst the (white) elite and tolerated chronic water insecurity amongst (black) informal dwellers. This uneven geography of water insecurity is also discernible in the unequal experiences of drought and water resilience trajectories of diverse social groups across Cape Town. We conclude that accounting for social power and inequalities can advance sociohydrology by identifying those mechanisms (within society) that determine what water is secured and what human-water interactions and dynamics will be sustained over time. Furthermore, by engaging with social power, sociohydrology can play a significant role in informing policies that reduce inequalities in water access and unsustainable water use.

Knowing how people perceive multiple risks is essential to the management and promotion of public health and safety. Here we present a dataset based on a survey (N = 4,154) of public risk perception in Italy and Sweden during the COVID-19 pandemic. Both countries were heavily affected by the first wave of infections in Spring 2020, but their governmental responses were very different. As such, the dataset offers unique opportunities to investigate the role of governmental responses in shaping public risk perception. In addition to epidemics, the survey considered indirect effects of COVID-19 (domestic violence, economic crises), as well as global (climate change) and local (wildfires, floods, droughts, earthquakes, terror attacks) threats. The survey examines perceived likelihoods and impacts, individual and authorities' preparedness and knowledge, and socio-demographic indicators. Hence, the resulting dataset has the potential to enable a plethora of analyses on social, cultural and institutional factors influencing the way in which people perceive risk.

Knowing how people perceive multiple risks is essential to the management and promotion of public health and safety. Here we present a dataset based on a survey (N = 4,154) of public risk perception in Italy and Sweden during the COVID-19 pandemic. Both countries were heavily affected by the first wave of infections in Spring 2020, but their governmental responses were very different. As such, the dataset offers unique opportunities to investigate the role of governmental responses in shaping public risk perception. In addition to epidemics, the survey considered indirect effects of COVID-19 (domestic violence, economic crises), as well as global (climate change) and local (wildfires, floods, droughts, earthquakes, terror attacks) threats. The survey examines perceived likelihoods and impacts, individual and authorities' preparedness and knowledge, and socio-demographic indicators. Hence, the resulting dataset has the potential to enable a plethora of analyses on social, cultural and institutional factors influencing the way in which people perceive risk.

Abstract. Global floodplain mapping has rapidly progressed over the past few years. Different methods have been proposed to identify areas prone to river flooding, resulting in a plethora of available products. Here we assess the potential and limitations of two main paradigms and provide guidance on the use of these global products in assessing flood risk in data-poor regions.

Abstract. Private risk reduction behaviours can significantly reduce the
negative impacts of flooding and flash floods. Over the past decades,
researchers have used various socio-cognitive models or threat and coping
mechanisms to explain individual protective behaviours. However, these
models ignore the fact that people are not equally ready to act upon a danger, and
they (the models) give limited insights into the effectiveness of communication
strategies to foster risk reduction behaviours. Therefore, we explored the
current state of homeowners' readiness to undertake risk reduction
behaviours in flood risk areas by applying a dynamic protection motivation
framework. We conducted a survey in an Italian municipality that experienced
severe flash flooding in September 2018. The results show that people are
motivated by different factors in prompting risk reduction behaviour based
on their chosen types of protective measures. For example, people that undertook
structural or avoidance measures are more likely to be motivated to protect
themselves by increased perceptions of vulnerability and response efficacy
and are less worried about expected flood losses compared to people that
undertook only basic emergency measures. In this paper, we argue how these
new insights contribute to targeting flood risk communication strategies to
groups of individuals characterized by different readiness stages and
motivations to protect themselves.

Multi-hazard events can be associated with larger socio-economic impacts than single-hazard events. Understanding the spatio-temporal interactions that characterize the former is therefore of relevance to disaster risk reduction measures. Here, we consider two high-impact hazards, namely wet and dry hydrological extremes, and quantify their global co-occurrence. We define these using the monthly self-calibrated Palmer Drought Severity Index based on the Penman-Monteith model (sc_PDSI_pm), covering the period 1950-2014, at 2.5 degrees horizontal resolution. We find that the land areas affected by extreme wet, dry, and wet-dry events (i.e. geographically remote yet temporally co-occurring wet or dry extremes) are all increasing with time, the trends of which in dry and wet-dry episodes are significant (p value « 0.01). The most geographically widespread wet-dry event was associated with the strong La Nina in 2010. This caused wet-dry anomalies across a land area of 21 million km(2) with documented high-impact flooding and drought episodes spanning diverse regions. To further elucidate the interplay of wet and dry extremes at a grid cell scale, we introduce two new metrics: the wet-dry (WD) ratio and the extreme transition (ET) time intervals. The WD ratio measures the relative occurrence of wet or dry extremes, whereas ET quantifies the average separation time of hydrological extremes with opposite signs. The WD ratio shows that the incidence of wet extremes dominates over dry extremes in the USA, northern and southern South America, northern Europe, north Africa, western China, and most of Australia. Conversely, dry extremes are more prominent in most of the remaining regions. The median ET for wet to dry is similar to 27 months, while the dry-to-wet median ET is 21 months. We also evaluate correlations between wet-dry hydrological extremes and leading modes of climate variability, namely the El Nina-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). We find that ENSO and PDO have a similar influence globally, with the former significantly impacting (p value < 0.05) a larger area (18.1 % of total sc_PDSI_pm area) compared to the latter (12.0 %), whereas the AMO shows an almost inverse pattern and significantly impacts the largest area overall (18.9 %). ENSO and PDO show the most significant correlations over northern South America, the central and western USA, the Middle East, eastern Russia, and eastern Australia. On the other hand, the AMO shows significant associations over Mexico, Brazil, central Africa, the Arabian Peninsula, China, and eastern Russia. Our analysis brings new insights on hydrological multi-hazards that are of relevance to governments and organizations with globally distributed interests. Specifically, the multi-hazard maps may be used to evaluate worst-case disaster scenarios considering the potential co-occurrence of wet and dry hydrological extremes.

Multi-hazard events can be associated with larger socio-economic impacts than single-hazard events. Understanding the spatio-temporal interactions that characterize the former is therefore of relevance to disaster risk reduction measures. Here, we consider two high-impact hazards, namely wet and dry hydrological extremes, and quantify their global co-occurrence. We define these using the monthly self-calibrated Palmer Drought Severity Index based on the Penman-Monteith model (sc-PDSI-pm), covering the period 1950-2014, at 2.5° horizontal resolution. We find that the land areas affected by extreme wet, dry, and wet-dry events (i.e. geographically remote yet temporally co-occurring wet or dry extremes) are all increasing with time, the trends of which in dry and wet-dry episodes are significant (p value ≪ 0.01). The most geographically widespread wet-dry event was associated with the strong La Niña in 2010. This caused wet-dry anomalies across a land area of 21 million km 2 with documented high-impact flooding and drought episodes spanning diverse regions. To further elucidate the interplay of wet and dry extremes at a grid cell scale, we introduce two new metrics: the wet-dry (WD) ratio and the extreme transition (ET) time intervals. The WD ratio measures the relative occurrence of wet or dry extremes, whereas ET quantifies the average separation time of hydrological extremes with opposite signs. The WD ratio shows that the incidence of wet extremes dominates over dry extremes in the USA, northern and southern South America, northern Europe, north Africa, western China, and most of Australia. Conversely, dry extremes are more prominent in most of the remaining regions. The median ET for wet to dry is ∼27 months, while the dry-to-wet median ET is 21 months. We also evaluate correlations between wet-dry hydrological extremes and leading modes of climate variability, namely the El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). We find that ENSO and PDO have a similar influence globally, with the former significantly impacting (p value < 0.05) a larger area (18.1 % of total sc-PDSI-pm area) compared to the latter (12.0 %), whereas the AMO shows an almost inverse pattern and significantly impacts the largest area overall (18.9 %). ENSO and PDO show the most significant correlations over northern South America, the central and western USA, the Middle East, eastern Russia, and eastern Australia. On the other hand, the AMO shows significant associations over Mexico, Brazil, central Africa, the Arabian Peninsula, China, and eastern Russia. Our analysis brings new insights on hydrological multi-hazards that are of relevance to governments and organizations with globally distributed interests. Specifically, the multi-hazard maps may be used to evaluate worst-case disaster scenarios considering the potential co-occurrence of wet and dry hydrological extremes.