Elisabeth Stephens's research while affiliated with University of Reading and other places

Publications (54)

Article
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Climate change and solar geoengineering have different implications for drought. Climate change can “speed up” the hydrological cycle, but it causesgreater evapotranspiration than the historical climate because of higher temperatures. Solar geoengineering (stratospheric aerosol injection), on the other hand, tends to “slow down” the hydrological cy...
Article
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...
Technical Report
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Impact based Forecasting (IbF) is an expanding and evolving area of research within National Meteorological and Hydrological Services (NMHSs) and the humanitarian sector, with a broad aim to enhance communication and timely action to reduce losses associated with natural hazards. Although the principles of IbF may seem new to some disciplines, they...
Article
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...
Article
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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...
Article
Weather forecasts, climate change projections, and epidemiological predictions all represent domains that are using forecast data to take early action for risk management. However, the methods and applications of the modeling efforts in each of these three fields have been developed and applied with little cross-fertilization. This perspective iden...
Article
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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...
Article
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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...
Article
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...
Preprint
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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...
Preprint
Full-text available
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...
Article
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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,...
Article
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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...
Article
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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...
Article
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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,...
Preprint
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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,...
Article
Full-text available
To inform the way probabilistic forecasts would be displayed on their website, the UK Met Office ran an online game as a mass participation experiment to highlight the best methods of communicating uncertainty in rainfall and temperature forecasts, and to widen public engagement in uncertainty in weather forecasting. The game used a hypothetical “i...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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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...
Article
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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...
Article
Full-text available
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...
Article
Full-text available
To inform the way probabilistic forecasts would be displayed on their website the UK Met Office ran an online game as a mass participation experiment to highlight the best methods of communicating uncertainty in rainfall and temperature forecasts, and to widen public engagement in uncertainty in weather forecasting. The game used a hypothetical ice...
Article
Full-text available
Global overviews of upcoming flood and drought events are key for many applications, including disaster risk reduction initiatives. Seasonal forecasts are designed to provide early indications of such events weeks or even months in advance, but seasonal forecasts for hydrological variables at large or global scales are few and far between. Here, we...
Chapter
Globally, floods are responsible for more than half of the total people affected by all weather‐related disasters combined, causing a large number of deaths and significant economic losses. Global‐scale flood forecasting systems play a key role in disaster risk reduction: they provide early flood information for several nations who are without loca...
Article
Full-text available
Global overviews of upcoming flood and drought events are key for many applications, including disaster risk reduction initiatives. Seasonal forecasts are designed to provide early indications of such events weeks, or even months, in advance, but seasonal forecasts for hydrological variables at large or global scales are few and far between. Here,...
Article
Full-text available
Extreme temperatures are one of the leading causes of death and disease in both developed and developing countries, and heat extremes are projected to rise in many regions. To reduce risk, heatwave plans and cold weather plans have been effectively implemented around the world. However, much of the world's population is not yet protected by such sy...
Preprint
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This paper presents a Europe-wide analysis of the skill of the newly operational EFAS (European Flood Awareness System) seasonal streamflow forecasts, benchmarked against the Ensemble Streamflow Prediction (ESP) forecasting approach. The results suggest that, on average, the System 4 seasonal climate forecasts improve the streamflow predictability...
Article
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This paper considers whether there is any added value in using seasonal climate forecasts instead of historical meteorological observations for forecasting streamflow on seasonal timescales over Europe. A Europe-wide analysis of the skill of the newly operational EFAS (European Flood Awareness System) seasonal streamflow forecasts (produced by forc...
Article
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In light of strong encouragement for disaster managers to use climate services for flood preparation, we question whether seasonal rainfall forecasts should indeed be used as indicators of the likelihood of flooding. Here, we investigate the primary indicators of flooding at the seasonal timescale across sub-Saharan Africa. Given the sparsity of hy...
Conference Paper
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The increased availability and application of probabilistic weather forecasts in flood forecasting means that the uncertainty arising from the precipitation forecast can be assessed. This has led to a wider interest in how uncertainty is affecting flood forecast systems. In literature there are general techniques and principles available on how to...
Article
Full-text available
To access paper: http://journals.ametsoc.org/doi/abs/10.1175/JHM-D-16-0259.1. Seasonal streamflow prediction skill can derive from catchment initial hydrological conditions (IHCs) and from the future seasonal climate forecasts (SCFs) used to produce the hydrological forecasts. Although much effort has gone into producing state-of-the-art seasonal s...
Article
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Link: http://www.nature.com/articles/ncomms14796 ; El Niño and La Niña events, the extremes of ENSO climate variability, influence river flow and flooding at the global scale. Estimates of the historical probability of extreme (high or low) precipitation are used to provide vital information on the likelihood of adverse impacts during extreme ENSO...
Data
Supplementary Table, Supplementary Figures and Supplementary References
Article
Full-text available
In light of strong encouragement for disaster managers to use climate services for flood preparation, we question whether seasonal rainfall forecasts should indeed be used as indicators of the likelihood of flooding. Here, we investigate the primary drivers of flooding at the seasonal timescale across sub-Saharan Africa. Given the sparsity of hydro...
Article
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Too often, credible scientific early warning information of increased disaster risk does not result in humanitarian action. With financial resources tilted heavily towards response after a disaster, disaster managers have limited incentive and ability to process complex scientific data, including uncertainties. These incentives are beginning to cha...
Article
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Probabilistic hydro-meteorological forecasts have over the last decades been used more frequently to communicate forecast uncertainty. This uncertainty is twofold, as it constitutes both an added value and a challenge for the forecaster and the user of the forecasts. Many authors have demonstrated the added (economic) value of probabilistic over de...
Article
Full-text available
Too often, credible scientific early warning information of increased disaster risk does not result in humanitarian action. With financial resources tilted heavily towards response after a disaster, disaster managers have limited incentive and ability to process complex scientific data, including uncertainties. These incentives are beginning to cha...
Article
Full-text available
Floods are the most frequent of natural disasters, affecting millions of people across the globe every year. The anticipation and forecasting of floods at the global scale is crucial to preparing for severe events and providing early awareness where local flood models and warning services may not exist. As numerical weather prediction models contin...
Preprint
Full-text available
In order to communicate forecast uncertainty, there has been a gradual adoption of probabilistic hydro-meteorological forecasts. This uncertainty is twofold, as it constitutes both an added value and a challenge for the forecaster and the user of the forecasts. Many authors have demonstrated the added (economic) value of probabilistic forecasts ove...
Article
There are a number of factors that lead to nonlinearity between precipitation anomalies and flood hazard; this nonlinearity is a pertinent issue for applications that use a precipitation forecast as a proxy for imminent flood hazard. We assessed the degree of this nonlinearity for the first time using a recently developed global-scale hydrological...
Article
An ability to quantify the reliability of probabilistic flood inundation predictions is a requirement not only for guiding model development but also for their successful application. Probabilistic flood inundation predictions are usually produced by choosing a method of weighting the model parameter space, but previous study suggests that this cho...
Chapter
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This chapter explores the practical challenges of communicating and using ensemble forecasts in operational flood incident management. It reviews recent social science research on the variety and effectiveness of HEPS visualization methods and on the cognitive and other challenges experienced by forecast recipients in understanding probabilistic fo...
Article
As the calibration and evaluation of flood inundation models are a prerequisite for their successful application, there is a clear need to ensure that the performance measures that quantify how well models match the available observations are fit for purpose. This paper evaluates the binary pattern performance measures that are frequently used to c...
Article
This winter (2013/14) coastal storms and an unprecedented amount of rainfall led to significant and widespread flooding across the southern UK. Despite much criticism and blame surrounding the flood events, the Flood Forecasting Centre, a recent development in national-level flood forecasting capabilities for the government and emergency response c...
Article
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Recent research into flood modelling has primarily concentrated on the simulation of inundation flow without considering the influences of channel morphology. River channels are often represented by a simplified geometry that is implicitly assumed to remain unchanged during flood simulations. However, field evidence demonstrates that significant mo...
Article
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The aim of this article is to improve the communication of the probabilistic flood forecasts generated by hydrological ensemble prediction systems (HEPS) by understanding perceptions of different methods of visualizing probabilistic forecast information. This study focuses on interexpert communication and accounts for differences in visualization r...
Article
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Climate model ensembles are widely heralded for their potential to quantify uncertainties and generate probabilistic climate projections. However, such technical improvements to modeling science will do little to deliver on their ultimate promise of improving climate policymaking and adaptation unless the insights they generate can be effectively c...
Article
The performance of flood inundation models is often assessed using satellite observed data; however, these data have inherent uncertainty. In this study we determine the patterns of uncertainty in an ERS-2 SAR image of flooding on the River Dee, UK and, using LISFLOOD-FP, evaluate how this uncertainty can influence the assessment of flood inundatio...
Article
The performance of flood inundation models is often assessed using satellite data; however, due to emergent vegetation, wind roughening and other factors these data have inherent uncertainty. Here, we develop a methodology to evaluate the impact of uncertainty in Synthetic Aperture Radar (SAR) observed flood extents on the calibration of the LISFLO...

Citations

... The permafrost associated with the alpine ecosystem has formed a stable cooperative relationship with vegetation in the long-term evolution in Qinghai Tibet Plateau [1,2]. However, influenced by climate change and human activity, the thermal state of permafrost is strongly affected [3,4], which leads to the degradation of permafrost and, consequently, the ecological environment of vegetation [5]. For example, changes in the ground surface hydrothermal conditions can easily lead to vegetation degradation [6,7]. ...
... While the SARS-CoV-2 pandemic has triggered an explosive growth of epidemiological forecasting models, substantially less research has been performed regarding how the results of such models should be disseminated for decision support [26][27][28] . In this work, therefore, we present the forecast and reporting system we developed based on the three independent forecasting models to support policy making in Austria. ...
... We find an asymptotic relationship between flood occurrence and extreme wind, as shown in Figure S4 in Supporting Information S1, indicating that more extreme floods are associated with relatively less extreme winds. This is likely because larger flood events tend to occur with slower moving cyclones, as they provide sufficient time for precipitation to augment river flows and heighten water levels (Lai et al., 2020;Titley et al., 2021), and slower moving cyclones are less intense in terms of wind speed (Eguchi et al., 2021). ...
... Spatial and temporal changes in land use, for example, alter the hydrological dynamics of watersheds (Legesse et al. 2003). It is also known that El Niño Southern Oscillation (ENSO) phenomena frequently affect tropical regions, and can cause increased or decreased rainfall rates, and spatial variability (Towner et al. 2021). It could be one of the possible causes of different CCF in the first quarter between 2009 and 2011, being aggravated, especially, at rainfall gauge stations far away from the analyzed catchments. ...
... This is reinforcing poverty, affecting more than 40 % of the region's 360 million people (Trisos et al., 2022). Several studies have reported severe consequences of climate extreme events on the agricultural sector, which is the main source of livelihood for many people in SSA (Ajetomobi, 2016;Ficchi et al., 2021;Fuller et al., 2018;Humphries et al., 2020;Wainwright et al., 2021b). The observed impacts of climate change on yields of most widely produced crops in sub-Saharan Africa (millet, maize, sorghum, and rice) have been reported by many studies (Amouzou et al., 2019, FAO and UNICEF, 2019, Atiah et al., 2022, Hadebe et al., 2017, Nyamekye et al., 2021, Oluwaranti et al., 2020. ...
... On average, six flood waves occur annually during the monsoon period in the lower basin, with discharge ranging from 4,420 m 3 s − 1 -51,156 m 3 s − 1 . Moderate floods occur once every 2 years, while severe floods occur every 6-7 years (Hossain et al., 2021). Between 1980 and 2012, a total of 38 flood events occurred, five of which were categorized under the level of devastating catastrophes (Hossain et al., 2021). ...
... In the case of precipitation, the structural term is reduced in central-eastern Brazil in JJA when the GEM-NEMO model is removed from the MME (Fig. 5a). According to previous works, the precipitation in this region is modulated by the SST anomalies of the tropical North Atlantic Ocean (TNA) (Ronchail et al. 2002;Yoon and Zeng 2009;Towner et al. 2020). The correlation between the observed precipitation in central-eastern Brazil and the SST over the TNA (Fig. 5d) is significant and negative. ...
... Until now, much of the research on AA has focused on the development of forecast products and systems to support and trigger AA (Coughlan de Perez et al., 2016;Emerton et al., 2020;Centre, 2021;Lala et al., 2021;MacLeod et al., 2021a;MacLeod et al., 2021b;Nauman et al., 2021;Boult et al., 2022). Studies have also attempted to demonstrate the benefits of AA compared to other forms of action (FAO, 2018a;FAO, 2018b;Gros et al., 2019;Bischiniotis et al., 2020;Gros et al., 2020;Weingärtner et al., 2020;Pople et al., 2021). ...
... Therefore, some global flood forecasting systems, such as GloFAS, use reanalysis to define the flood threshold to account for these biases. However, Zsoter et al. (2020;[EZ-P]) showed that lead-time dependent ensemble reforecast-based thresholds provide even more reliable and skilful flood forecasts for longer lead-times since biases in the forecast due to the use of NWP models rather than meteorological observations are also accounted for. ...
... Co-production and the incorporation of local knowledge have been identified as a research track that is crucial to study how global forecasting systems can be incorporated into local decision making, and how largescale systems and data can better use local knowledge and experiences (see Arnal et al., 2020). Part of this process is to identify the 'user'. ...