Thorsten Wagener

Universität Potsdam · Institut für Umweltwissenschaften und Geographie

Removing carbon dioxide (CO 2 ) from the atmosphere is required for mitigating climate change. Large-scale direct air capture combined with injecting CO 2 into geological formations could retain carbon long-term, but demands a substantial amount of energy, pipeline infrastructure, and suitable sites for gaseous storage. Here, we study Earth system...

Topography affects the distribution and movement of water on Earth, yet new insights about topographic controls continue to surprise us and exciting puzzles remain. Here we combine literature review and data synthesis to explore the influence of topography on the global terrestrial water cycle, from the atmosphere down to the groundwater. Above the...

Hydrological parameters are used to tailor simulation models to the specific characteristics of a catchment so that models can accurately represent processes under different catchment conditions. In the case of the mesoscale Hydrological Model (mHM), its parameters are estimated via transfer functions using the Multiscale Parameter Regionalization...

The term "Digital Twins of the Earth" has rocketed into scientific use and policymaker discourse by promising a virtual replica of our planet. While the potential of a digital representation of reality is captivating for environmental monitoring, decision-making, and scientific inquiry, the term lacks a clear and shared definition and may be mislea...

Individual approaches to observe water dynamics across our landscape, from the land surface to groundwater, are many though they individually only provide glimpses into the real world due to their specific space–time scales. Comprehensive integration across all available observations is still largely lacking, limiting both our ability to reduce sci...

Groundwater is crucial to sustaining coastal freshwater needs. About 32 million people in the coastal USA rely on groundwater as their primary water source. With rapidly growing coastal communities and increasing demands for fresh groundwater, understanding controls of continental-scale coastal groundwater salinity is critical. To investigate what...

Knowing the depth at which groundwater can be found below the land surface is critical for understanding its potential accessibility by ecosystems and society. Uncertainty in global scale water table depth (WTD) limits our ability to assess groundwater’s role in a water cycle altered by changing climate, land cover, and human water use. Global grou...

Inverse problems aim at determining model parameters that produce observed data to subsequently understand, predict or manage hydrological or other environmental systems. While statistical inversion is especially popular, its sampling‐based nature often inhibits its application to computationally costly models, which has compromised the use of the...

Floods, droughts, and rainfall‐induced landslides are hydro‐hazards that affect millions of people every year. Anticipation, mitigation, and adaptation to these hazards is increasingly outpaced by their changing magnitude and frequency due to climate change. A key question for society is whether the research we pursue has the potential to address k...

Rainfall-triggered landslides are most deadly in developing countries, and future urban sprawl and climate change could intensify existing risks. In these regions, enhancing efforts in urban landslide risk mitigation and climate change adaptation is crucial. Current landslide probability assessment methodologies struggle to support effective mitiga...

Inverse problems are ubiquitous in hydrological modelling for parameter estimation, system understanding, sustainable water resources management, and the operation of digital twins. While statistical inversion is especially popular, its sampling-based nature often inhibits its application to computationally costly models, which has compromised the...

The ability to characterize hydrologically relevant differences between places is at the core of our science. A common way to quantitatively characterize hydrological catchments is through the use of descriptors that summarize relevant physical aspects of the system, typically by aggregating heterogeneous geospatial information into a single number...

Climate change is increasing the likelihood of drought in sub-Saharan Africa, where HIV prevalence is high. Drought could increase HIV transmission through various mediating mechanisms; we investigated these associations. We used data on people aged 15–59 from Population-Based HIV Impact Assessment surveys from 2016 in Eswatini, Lesotho, Tanzania,...

Central Europe, including Germany, has faced exceptional multi-year terrestrial water storage (TWS) deficits since 2018, negatively impacting various sectors such as forestry, energy production, and drinking water supply. Currently, the understanding of the recovery dynamics behind such extreme events is limited, which hampers accurate water manage...

Floods, droughts, and rainfall-induced landslides are hydro-geomorphic hazards that affect millions of people every year. Anticipation, mitigation, and adaptation to these hazards is increasingly outpaced by their changing magnitude and frequency due to climate change. A key question for society is whether the research we pursue has the potential t...

Background Periods of droughts can lead to decreased food security, and altered behaviours, potentially affecting outcomes on antiretroviral therapy (ART) among persons with HIV (PWH). We investigated whether decreased rainfall is associated with adverse outcomes among PWH on ART in Southern Africa. Methods Data were combined from 11 clinical coho...

Global water models are increasingly used to understand past, present and future water cycles, but disagreements between simulated variables make model-based inferences uncertain. Although there is empirical evidence of different large-scale relationships in hydrology, these relationships are rarely considered in model evaluation. Here we evaluate...

Rainfall‐runoff models are commonly evaluated against statistical evaluation metrics. However, these metrics do not provide much insight into what is hydrologically wrong if a model fails to simulate observed streamflow well and they are also not applicable for ungauged catchments. Here, we propose a signature‐based hydrologic efficiency (SHE) metr...

Inverse problems are ubiquitous in hydrological modelling for parameter estimation, system understanding, sustainable water resources management, and the operation of digital twins. While statistical inversion is especially popular, its sampling-based nature often inhibits the inversion of computationally costly models, which has compromised the us...

Functional relationships capture how variables co-vary across specific spatial or temporaldomains. However, these relationships often take complex forms beyond linear, and they mayonly hold for sub-sets of the domain. More problematically, it is often a priori unknown howsuch sub-domains are defined. Here we present a new method called SONAR (diSco...

Forester is a web-based and open-source software that produces visually appealing tree-based illustrations of already trained classification trees from arbitrary libraries or languages (currently Matlab and R). It creates publication-quality plots, that are, at the same time, interactive figures that can guide the user in exploring their tree-based...

An ability to describe hydrologically relevant differences between places is at the core of our science. A common way to characterize hydrological catchments is to use descriptors that summarize important physical aspects of the system, often by aggregating heterogeneous geospatial data into a single number. Such descriptors aim to capture various...

There is a general trend toward the increasing inclusion of uncertainty estimation in the environmental modelling domain. We present the Consortium on Risk in the Environment: Diagnostics, Integration, Benchmarking, Learning and Elicitation (CREDIBLE) Uncertainty Estimation (CURE) toolbox, an open-source MATLABTM toolbox for uncertainty estimation...

Global hydrological models (GHMs) supply key information for stakeholders and policymakers simulating past, present and future water cycles. Inaccuracy in GHM simulations, i.e., simulation results that poorly match observations, leads to uncertainty that hinders valuable decision support. Improved parameter estimation is one key to more accurate si...

Fresh submarine groundwater discharge (SGD) and seawater intrusion (SWI) are complementary processes at the interface of coastal groundwater and oceans. Multiple common drivers enable or limit SGD and SWI. However, we find that SGD and SWI are rarely studied simultaneously. In this meta-analysis, we synthesize 1298 publications, examining drivers o...

Rainfall-runoff models are commonly evaluated against statistical evaluation metrics. However, these metrics do not provide much insight into what is hydrologically wrong if a model fails to simulate observed streamflow well and they are also not applicable for ungauged catchments. Here, we propose a signature-based hydrologic efficiency (SHE) metr...

Flooding is one of the most common natural hazards, causing disastrous impacts worldwide. Stress-testing the global human-Earth system to understand the sensitivity of floodplains and population exposure to a range of plausible conditions is one strategy to identify where future changes to flooding or exposure might be most critical. This study pre...

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 fe...

At what depth groundwater can be found below the land surface is key to understanding whether it is potentially accessible to ecosystems and humans, or what role it plays in the water cycle. Knowledge of ground-water table depth (WTD) exists at regional scales in many places, but a bottom-up knowledge aggregation to obtain a coherent global picture...

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 fee...

To describe process knowledge at the watershed scale, hydrologists commonly refer to a ‘perceptual model’, an expert summary of the watershed and its runoff processes often supported by field observations. Perceptual models are often presented as a schematic figure, although such a figure will necessarily simplify the hydrologist's complex mental m...

Decision Trees (DT) describe a type of machine learning method that has been widely used in the geosciences to automatically extract patterns from complex and high dimensional data. However, like any data-based method, the application of DT is hindered by data limitations, such as significant biases, leading to potentially physically unrealistic re...

Global water models are widely used for policy-making and in scientific studies, but substantial inter-model differences highlight the need for additional evaluation. Here we evaluate global water models by assessing so-called functional relationships between system forcing and response variables. The more widely used comparisons between observed a...

There is a general trend for increasing inclusion of uncertainty estimation in the environmental modelling domain. We present the CREDIBLE Uncertainty Estimation (CURE) Toolbox, an open source MATLABTM toolbox for uncertainty estimation aimed at scientists and practitioners that are not necessarily experts in uncertainty estimation. The toolbox foc...

Climate change may significantly increase flood risk globally, but there are large uncertainties in both future climatic changes and how these propagate into changing river flows. Here, the impact of climate change on the magnitude and frequency of high flows is analysed for Great Britain (GB) to provide the first spatially consistent GB projection...

Empirical evidence shows that climate, deforestation and informal housing (i.e. unregulated construction practices typical of fast-growing developing countries) can increase landslide occurrence. However, these environmental changes have not been considered jointly and in a dynamic way in regional or national landslide susceptibility assessments. T...

Increasing publication numbers make it difficult to keep up with knowledge evolution in a science like hydrology. Here we give recommendations to authors and journals for writing future‐proof articles that contribute to knowledge accumulation and synthesis. Increasing publication numbers make it difficult to keep up with knowledge evolution in a sc...

Groundwater is an essential resource for natural and human systems throughout the world and the rates at which aquifers are recharged constrain sustainable levels of consumption. However, recharge estimates from global-scale models regularly disagree with each other and are rarely compared to ground-based estimates. We compare long-term mean annual...

More settlements will suffer as heavy rains and unregulated construction destabilize slopes in the tropics, models show.

The following information in sections of Study Area, Data, and Methods, together with Figures S1 to S6 and Table S1, constitutes the hypothesis of the main article. Here we cite more references on which the original study relies.

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 sh...

Empirical evidence shows that climate, deforestation and informal housing (i.e. unregulated construction practices typical of fast-growing developing countries) can increase landslide occurrence. These environmental changes have not been considered jointly and in a dynamic way in regional or national landslide susceptibility assessments. Considerin...

Groundwater is critical in supporting current and future reliable water supply throughout Africa. Although continental maps of groundwater storage and recharge have been developed, we currently lack a clear understanding on how the controls on groundwater recharge vary across the entire continent. Reviewing the existing literature, we synthesize in...

The climate crisis illustrates the critical need for earth and environmental models to assess the Earth’s past and future by translating emissions into climate signals and subsequent impacts regarding floods, droughts, or heatwaves, as well as future resource availability. While computational models grow in relevance by guiding policies and public...

In‐depth understanding of the potential implications of climate change is required to guide decision‐ and policy‐makers when developing adaptation strategies and designing infrastructure suitable for future conditions. Impact models that translate potential future climate conditions into variables of interest are needed to create the causal connect...

The need for a catchment classification framework for the Congo Basin is obvious given the basin's inherent heterogeneities, the ungauged nature of the basin, and the pressing needs for water resources management that include the quantification of current and future supplies and demands, which also encompass the impacts of future changes associated...

La nécessité de mettre en place un cadre de classification des unités hydrologiques est évidente dans le Bassin du Congo à cause de ses hétérogénéités, de sa nature non jaugée et des besoins pressants d'utilisation des ressources en eau. Ces besoins comprennent la quantification des approvisionnements et des demandes actuels et futures, qui incluen...

Detailed understanding of the potential local or regional implications of climate change is required to guide decision- and policy-makers when developing adaptation strategies and designing infrastructure solutions suitable for potential future conditions. Impact models that translate potential future climate conditions into variables of interest (...

Groundwater is the primary drinking water supply of billions of people worldwide. While groundwater is under pressure globally due to extensive water abstractions, proximity to coasts amplifies these pressures due to potential sea water intrusion that can endanger groundwater quality. It is unclear how climate change (changing potential groundwater...

Groundwater is an essential resource for natural and human systems throughout the world and the rates at which aquifers are recharged constrain sustainable levels of consumption. However, recharge estimates from global-scale models regularly disagree with each other and are rarely compared to ground-based estimates. We compare long-term mean annual...

Groundwater is critical in supporting current and future reliable water supply throughout Africa. Although continental maps of groundwater storage and recharge have been developed, we currently lack a clear understanding on how the controls on groundwater recharge vary across the entire continent. Reviewing the existing literature, we synthesize in...

Continental- to global-scale hydrologic and land surface models increasingly include representations of the groundwater system. Such large-scale models are essential for examining, communicating, and understanding the dynamic interactions between the Earth system above and below the land surface as well as the opportunities and limits of groundwate...

Spatial parameter fields are required to model hydrological processes across diverse landscapes. Transfer functions are often used to relate parameters to spatial catchment attributes, introducing large uncertainties. Quantifying these uncertainties remains a key challenge for large‐scale modeling. This paper extends the multiscale parameter region...

The analysis of large samples of hydrologic catchments is regularly used to gain understanding of hydrologic variability and controlling processes. Several studies have pointed towards the problem that available catchment descriptors (such as mean topographic slope or average subsurface properties) are insufficient to capture hydrologically relevan...

Our ability to fully and reliably observe and simulate the terrestrial hydrologic cycle is limited, and in‐depth experimental studies cover only a tiny fraction of our landscape. On medieval maps, unexplored regions were shown as images of dragons—displaying a fear of the unknown. With time, cartographers dared to leave such areas blank, thus invit...

Decision Trees (DT) is a machine learning method that has been widely used in the environmental sciences to automatically extract patterns from complex and high dimensional data. However, like any data-based method, is hindered by data limitations and potentially physically unrealistic results. We develop interactive DT (iDT) that put the human in...

Climate change may significantly increase flood risk across Great Britain (GB), but there are large uncertainties in both future climatic changes and how these propagate into changing river flows. Here, the impact of climate change on the magnitude and frequency of high flows is modelled for 346 larger (> 144 km2) catchments across GB using the lat...

The growing worldwide impact of flood events has motivated the development and application of global flood hazard models (GFHMs). These models have become useful tools for flood risk assessment and management, especially in regions where little local hazard information is available. One of the key uncertainties associated with GFHMs is the estimati...

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 Water Informatics in Science and Engineering Centre for Doctoral Training (WISE CDT) offers a postgraduate programme that fosters enhanced levels of innovation and collaboration by training a cohort of engineers and scientists at the boundary of water informatics, science and engineering. The WISE CDT was established in 2014 with funding from t...