Hannah L Cloke

• Professor at University of Reading

Existing global river networks underpin a wide range of hydrological applications but do not represent channels with divergent river flows (bifurcations, multi‐threaded channels, canals), as these features defy the convergent flow assumption that elevation‐derived networks (e.g., HydroSHEDS, MERIT Hydro) are based on. Yet, bifurcations are importan...

What’s the worst that could happen? After a flood has devasted communities, those people affected, the news media, and the authorities often say that what happened was beyond our imagination. Imagination encompasses the picturing of a situation in our mind linked with the emotions that we connect with this situation. However, the role imagination a...

Atmospherically generated coastal waves labelled as meteotsunami are known to cause destruction, injury, and fatality due to their rapid onset and unexpected nature. Unlike other coastal hazards such as tsunami, there exist no standardised means of quantifying this phenomenon, which is crucial to understand shoreline impacts and to enable researche...

Citizen priorities, needs, and rights have been moving to the centre of ‘good’ risk management and governance in theory, but what is their role in practice? The disastrous impacts of the flooding event across western Europe in 2021 highlighted many gaps and challenges in flood risk governance (FRG) structures in Germany. To better understand these,...

Fluvial flooding is a major cause of death and damages from tropical cyclones (TCs), so it is important to understand the predictability of river flooding in TC cases, and the potential of global ensemble flood forecast systems to inform warning and preparedness activities. This paper demonstrates a methodology using ensemble forecasts to follow pr...

Scientific and technical changes to flood forecasting models are implemented to improve forecasts. However, responses to such changes are complex, particularly in global models, and evaluation of improvements remains focussed on generalised skill assessments and not on the most relevant outcomes for those taking decisions. Recently, the Global Floo...

International humanitarian organisations increasingly turn to forecast teams to support the coordination of efforts to respond to disasters caused by hazards such as tropical cyclones and large‐scale fluvial floods. Such disasters often occur where there is limited local capacity or information available to support decision making and so global for...

A large number of historical simulations and future climate projections are available from Global Climate Models, but these are typically of coarse resolution, which limits their effectiveness for assessing local scale changes in climate and attendant impacts. Here, we use a novel statistical downscaling model capable of replicating extreme events,...

This paper examines the occurrence and seasonality of meteotsunami in the United Kingdom (UK) to present a revised and updated catalogue of events that have occurred since 1750. Previous case studies have alluded to a summer prevalence and rarity of this hazard in the UK. We have verified and classified 98 events using a developed set of identifica...

Over the past decades, the scientific community has made significant efforts to simulate flooding conditions using a variety of complex physically based models. Despite all advances, these models still fall short in accuracy and reliability and are often considered computationally intensive to be fully operational. This could be attributed to insuf...

Atmospherically generated coastal waves labelled as meteotsunami are known to cause destruction, injury and fatality due to their rapid onset and unexpected nature. Unlike other coastal hazards such as tsunami, there exists no standardised means of quantifying this phenomenon which is crucial for understanding shoreline impacts and to enable resear...

Natural flood management (NFM) is widely promoted for managing flood risks but the effectiveness of different types of NFM schemes at medium (100–1000 km ² ) and large scales (>1000 km ² ) remains widely unknown. This study demonstrates the importance of fully understanding the impact of model structure, calibration and uncertainty techniques on th...

Over the past two decades, more than 80 metropolitan cities across the world have faced severe water shortages due to droughts and unsustainable water use. Future projections are even more alarming, since urban water crises are expected to escalate and most heavily affect those who are socially, economically and politically disadvantaged. Here we s...

The flooding event in Germany in 2021 caused fatal and devastating consequences for the citizens, economy, infrastructure, and more. Research has been focusing on analyzing the meteorological and hydrological aspects of the flooding, the early warning system and warning dissemination, and the flood impact. However, research is lacking a deeper unde...

The Wet Bulb Globe Temperature (WBGT) is an international standard heat index used by the health, industrial, sports, and climate sectors to assess thermal comfort during heat extremes. Observations of its components, the globe and the wet bulb temperature (WBT), are however sparse. Therefore WBGT is difficult to derive, making it common to rely on...

The unprecedented progress in ensemble hydro‐meteorological modelling and forecasting on a range of temporal and spatial scales, raises a variety of new challenges which formed the theme of the Joint Virtual Workshop, ‘Connecting global to local hydrological modelling and forecasting: challenges and scientific advances’. Held from 29 June to 1 July...

Operational global-scale hydrological forecasting systems are used to help manage hydrological extremes such as floods and droughts. The vast amounts of raw data that underpin forecast systems and the ability to generate information on forecast skill have, until now, not been publicly available. As part of the Global Flood Awareness System (GloFAS;...

This paper examined the occurrence and seasonality of meteotsunami in the United Kingdom (UK) to present a revised and updated catalogue of events occurring since 1750. Previous case studies have alluded to a summer prevalence and rarity of this hazard in the UK. We have verified and classified 95 events using a developed set of identification crit...

Human actions are increasingly altering most river basins worldwide, resulting in changes in hydrological processes and extreme events. Yet, global patterns of changes between seasonal surface water and urbanization remain largely unknown. Here we perform a worldwide analysis of 106 large river basins and uncover global trends of annual maximum flo...

This paper conceptualises droughts as socioecological phenomena coproduced by the recursive engagement of human and non-human transformations. Through an interdisciplinary approach that integrates political ecology, material geographies and hydroclimatology, this work simultaneously/home/ene apprehends the role of politics and power in reshaping dr...

A ‘roadmap’ for the future of UK flood hydrology over the next 25 years has been published, based on a wide-ranging and inclusive co-creation process involving more than 270 individuals and 50 organisations from different sectors and disciplines. This paper highlights key features of the roadmap and its development as a community-owned initiative....

The choice of model for operational flood forecasting is not simple because of different process representations, data scarcity issues, and propagation of errors and uncertainty down the modeling chain. An objective decision needs to be made for the choice of the modeling tools. However, this decision is complex because all parts of the process hav...

In June 2021, an unprecedented extreme heatwave impacted the Pacific Northwest of North America, resulting in more than 1000 excess deaths and affecting infrastructure and wildlife. Predicting such extreme events is key for preparedness and early action, and beyond temperature, it is important to consider biometeorological forecasts, accounting for...

Streamflow forecasts provide vital information to aid emergency response preparedness and disaster risk reduction. Medium-range forecasts are created by forcing a hydrological model with output from numerical weather prediction systems. Uncertainties are unavoidably introduced throughout the system and can reduce the skill of the streamflow forecas...

Here the development of the python library thermofeel is described. thermofeel was developed so that prominent internationally used thermal indices (i.e. Universal Thermal Climate Index and Wet Bulb Globe Temperature) could be implemented into operational weather forecasting systems (i.e. the European Centre for Medium Range Weather Forecasts) whil...

Study region 19 flood prone catchments in Kenya, Eastern Africa Study focus Flooding is a major natural hazard especially in developing countries, and the need for timely, reliable, and actionable hydrological forecasts is paramount. Hydrological modelling is essential to produce forecasts but is a challenging task, especially in poorly gauged cat...

The representation of snow is a crucial aspect of land-surface modelling, as it has a strong influence on energy and water balances. Snow schemes with multiple layers have been shown to better describe the snowpack evolution and bring improvements to soil freezing and some hydrological processes. In this paper, the wider hydrological impact of the...

Quaternary Caspian Sea level variations depended on geophysical processes (affecting the opening and closing of gateways and basin size/shape) and hydro-climatological processes (affecting water balance). Disentangling the drivers of past Caspian Sea level variation, as well as the mechanisms by which they impacted the Caspian Sea level variation,...

Supplementary information for "What are the drivers of Caspian Sea level variation during the late Quaternary?"

Supplementary information for "What are the drivers of Caspian Sea level variation during the late Quaternary?"

Nature-based Solutions function as an umbrella concept for ecosystem-based approaches that are an alternative to traditional engineering solutions for Disaster Risk Reduction. Their rising popularity is explained partly by their entailing additional benefits (so called co-benefits) for the environment, society, and economy. The few existing framewo...

The cosine of the solar zenith angle (cossza) is a key component in Mean Radiant Temperature (MRT). Mean Radiant Temperature is used in the calculation of the Universal Thermal Climate Index (UTCI) and can be used in the calculation of Globe Temperature a component of the Wet Bulb Globe Temperature (WBGT), both of which are important thermal comfor...

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 t...

Uganda Red Cross Society (URCS) in collaboration with the Red Cross Red Crescent Climate Centre (RCCC), works with the support of the Uganda National Meteorological Authority (UNMA), the Directorate of Water Resources Management (DWRM), alongside international partners, including 510-global and the University of Reading (UK) through the UK-supporte...

Streamflow forecasts provide vital information to aid emergency response preparedness and disaster risk reduction. Medium-range forecasts are created by forcing a hydrological model with output from numerical weather prediction systems. Uncertainties are unavoidably introduced throughout the system and can reduce the skill of the streamflow forecas...

The construction of flooding and flood risk management are complex and there is potential for dissonance between individual and institutional understanding and experience of both. In this article, we start by investigating how flooding is managed and the change in paradigm from flood defence to more adaptive approaches, which embed resilience into...

In 2019, a heatwave - an unusual extended period of hot weather - broke the UK's highest recorded temperature of 38.7°C set in 2003. Of concern is that for summer 2019, this resulted in 892 excess deaths. With the intensity and frequency of UK heatwaves projected to increase, and summer temperatures predicted to be 5°C hotter by 2070, urgent action...

The Caspian Sea (CS) is the largest inland lake in the world. Large variations in sea level and surface area occurred in the past and are projected for the future. The potential impacts on regional and large‐scale hydroclimate are not well understood. Here, we examine the impact of CS area on climate within its catchment and across the northern hem...

Supplementary information for "Impacts of Variations in Caspian Sea Surface Area on Catchment-Scale and Large-Scale Climate."

Heatwaves are increasing in frequency, duration, and intensity due to climate change. They are associated with high mortality rates and cross‐sectional impacts including a reduction in crop yield and power outages. Here we demonstrate that there are large deficiencies in reporting of heatwave impacts in international disasters databases, internatio...

Heatwaves pose an ever increasing risk to African communities as exposure to heat extremes can have a drastic effect on individuals and in some cases can even result in death. This study presents new information about the characteristics of historical African heatwaves including a comprehensive synopsis of documented heatwave events from 1980 until...

The Caspian Sea (CS) delivers considerable ecosystem services to millions of people. It experienced water level variations of 3 m during the 20th century alone. Robust scenarios of future CS level are vital to inform environmental risk management and water-use planning. In this study we investigated the water budget variation in the CS drainage bas...

Supplementary information for "The fate of the Caspian Sea under projected climate change and water extraction during the 21st century."

Floods have devastating effects on lives and livelihoods around the world. Structural flood defense measures such as dikes and dams can help protect people. However, it is the emerging science and technologies for flood disaster management and preparedness, such as increasingly accurate flood early warning systems, high-resolution satellite monitor...

Predicting floods and droughts is essential to inform the development of policy in water management, climate change adaptation and disaster risk reduction. Yet, hydrological predictions are highly uncertain, while the frequency, severity and spatial distribution of extreme events are further complicated by the increasing impact of human activities...

The Caspian Sea (CS) delivers considerable ecosystem services to millions of people. It experienced water level variations of 3 m during the 20th century alone. Robust scenarios of future CS level are vital to inform environmental risk management and water-use planning. In this study we investigated the water budget variation in the CS drainage bas...

Knowledge of the key drivers of the severity of river flooding from tropical cyclones (TCs) is vital for emergency preparedness and disaster risk reduction activities. This global study examines landfalling TCs in the decade from 2010 to 2019 to identify those characteristics that influence whether a storm has an increased flood hazard. The highest...

Flooding in the Amazon basin is frequently attributed to modes of large-scale climate variability, but little attention is paid to how these modes influence the timing and duration of floods despite their importance to early warning systems and the significant impacts that these flood characteristics can have on communities. In this study, river di...

thermofeel (pronounced thermo-feel) is a library to calculate human thermal comfort indexes. It includes the Universal Thermal Climate Index and a new method for computing the Wet bulb globe temperature.

Remotely sensed flood extents obtained in near real-time can be used for emergency flood incident management and as observations for assimilation into flood forecasting models. High-resolution synthetic aperture radar (SAR) sensors have the potential to detect flood extents in urban areas through clouds during both day- and night-time. This paper c...

There is a no lack of significant open questions in the field of hydrology. How will hydrological connectivity between freshwater bodies be altered by future human alterations to the hydrological cycle? Where does water go when it rains? Or what is the future space-time variability of flood and drought events? However, the answers to these question...

The El Niño Southern Oscillation (ENSO) dominates the conversation about predictability of climate extremes and early warning and preparedness for floods and droughts, but in Africa other modes of climate variability are also known to influence rainfall anomalies. In this study, we compare the role of ENSO in driving flood hazard over sub-Saharan A...

Air temperature has been the most commonly used exposure metric in assessing relationships between thermal stress and mortality. Lack of the high-quality meteorological station data necessary to adequately characterize the thermal environment has been one of the main limitations for the use of more complex thermal indices. Global climate reanalyses...

Nature-based solutions are increasingly implemented to tackle disaster risk reduction and climate change adaptation. Their rising popularity over grey solutions is partially explained by their number of additional benefits (so called co-benefits) for the socio-ecological system (SES). Frameworks are available to monitor and assess co-benefits, howe...

While flooding is an annual occurrence in the Brahmaputra basin during the South Asian summer monsoon, there is large variability in the flood characteristics that drive risk: flood duration, rate of water level rise and peak water level. The aim of this study is to understand the key hydrometeorological drivers influencing these flood characterist...

Remote sensing using synthetic aperture radar (SAR) is an important tool for emergency flood incident management. At present, operational services are mainly aimed at flood mapping in rural areas, as mapping in urban areas is hampered by the complicated backscattering mechanisms occurring there. A method for detecting flooding at high resolution in...

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...

Flooding in the Amazon basin is frequently attributed to modes of large-scale climate variability, but little attention is paid to how these modes influence the timing and duration of floods despite their importance to early warning systems and the significant impacts that these flood characteristics can have on communities. In this study, river di...

Anomalous conditions in the oceans and atmosphere have the potential to be used to enhance the predictability of flood events, enabling earlier warnings to reduce risk. In the Amazon basin, extreme flooding is consistently attributed to warmer or cooler conditions in the tropical Pacific and Atlantic oceans, with some evidence linking floods to oth...

Operational global-scale hydrological forecasting systems are widely used to help manage hydrological extremes such as floods and droughts. The vast amounts of raw data that underpin forecast systems and the ability to generate information on forecast skill have, until now, not been publicly available. As part of the Global Flood Awareness System (...

Humanitarian disasters such as Typhoon Haiyan (SE Asia, 2013) and the Horn of Africa drought (2011–2012) are examples of natural hazards that were predicted, but where forecasts were not sufficiently acted upon, leading to considerable loss of life. These events, alongside international adoption of the Sendai Framework for Disaster Risk Reduction,...

Estimating how much water is flowing through rivers at the global scale is challenging due to a lack of observations in space and time. A way forward is to optimally combine the global network of earth system observations with advanced numerical weather prediction (NWP) models to generate consistent spatio-temporal maps of land, ocean, and atmosphe...

Global flood forecasting systems rely on predefining flood thresholds to highlight potential upcoming flood events. Existing methods for flood threshold definition are often based on reanalysis datasets using a single threshold across all forecast lead times, such as in the Global Flood Awareness System. This leads to inconsistencies between how th...

By showing the uncertainty surrounding a prediction, probabilistic forecasts can give an earlier indication of potential upcoming floods, increasing the amount of time available to prepare. However, making a decision based on probabilistic information is challenging. As part of the UK-wide policy's move towards forecast-based flood risk management,...

The mean radiant temperature (MRT) and the Universal Thermal Climate Index (UTCI) are widely used as human biometeorology parameters to assess the linkages between outdoor environment and human well-being. Historically computed from meteorological station measurements, we here present ERA5-HEAT (Human thErmAl comforT), the first historical dataset...

Plain Language Summary Ensemble forecasts show the range of weather scenarios that can occur, allowing users to make appropriate risk‐based decisions. An ensemble forecast made 2 weeks in advance will show a range of possible outcomes. New observations included in subsequent forecasts will eliminate some of these scenarios, and the forecast will be...

IMproving PRedictions and management of hydrological EXtremes (IMPREX) was a European Union Horizon 2020 project that ran from September 2015 to September 2019. IMPREX aimed to improve society’s ability to anticipate and respond to future extreme hydrological events in Europe across a variety of uses in the water-related sectors (flood forecasting,...

Abstract. Abstract. Estimating how much water is flowing through rivers at the global scale is challenging due to a lack of observations in space and time. A way forward is to optimally combine the global network of earth system observations with advanced numerical weather prediction (NWP) models to generate consistent spatio-temporal maps of land,...

At the Met Office, dynamic ensemble forecasts from the Met Office Global and Regional Ensemble Prediction System (MOGREPS‐G), the European Centre for Medium‐Range Weather Forecasts Ensemble (ECMWF ENS) and National Centers for Environmental Prediction Global Ensemble Forecast System (NCEP GEFS) global ensemble forecast models are post‐processed to...

This work explores the question "How can data on flood extents derived from Earth Observations (EO) be used to assess the performance of a global flood forecasting model in the ungauged catchment of the Okere and Okok Rivers in Uganda?". The Global Flood Awareness System (GloFAS), jointly developed by the European Commission and the European Centre...

The inclusion of uncertainty in flood forecasts is a recent, important yet challenging endeavour. In the chaotic and far from certain world we live in, probabilistic estimates of potential future floods are vital. By showing the uncertainty surrounding a prediction, probabilistic forecasts can give an earlier indication of potential future floods,...

Extreme flooding impacts millions of people that live within the Amazon floodplain. Global hydrological models (GHMs) are frequently used to assess and inform the management of flood risk, but knowledge on the skill of available models is required to inform their use and development. This paper presents an intercomparison of eight different GHMs fr...

Flooding is a frequent natural hazard in the Brahmaputra basin during the South Asian summer monsoon. Understanding the causes of flood severity is essential for flood management decisions, but to date there has been little attempt to identify sub-seasonal variability of flood characteristics and drivers for the Brahmaputra in Bangladesh. In the 20...

Heat stress and forest fires are often considered highly correlated hazards as extreme temperatures play a key role in both occurrences. This commonality can influence how civil protection and local responders deploy resources on the ground and could lead to an underestimation of potential impacts, as people could be less resilient when exposed to...

Land surface models (LSMs) have traditionally been designed to focus on providing lower-boundary conditions to the atmosphere with less focus on hydrological processes. State-of-the-art application of LSMs includes a land data assimilation system (LDAS), which incorporates available land surface observations to provide an improved realism of surfac...

The authors wish to make the following corrections to this paper [...]

Environmental Research Communications. Open Access Link: https://iopscience.iop.org/article/10.1088/2515-7620/ab114e Abstract. In the past, efforts to prepare for the impacts of El Niño-driven flood and drought hazards have often relied on seasonal precipitation forecasts as a proxy for hydrological extremes, due to a lack of hydrologically rele...

Heatwaves represent a threat to human health and excess mortality is one of the associated negative effects. A health-based definition for heatwaves is therefore relevant, especially for early warning purposes, and it is here investigated via the Universal Thermal Climate Index (UTCI). The UTCI is a bioclimate index elaborated via an advanced model...

The FRANC project (Forecasting Rainfall exploiting new data Assimilation techniques and Novel observations of Convection) has researched improvements in numerical weather prediction of convective rainfall via the reduction of initial condition uncertainty. This article provides an overview of the project’s achievements. We highlight new radar techn...