Public information:
You can download the file with the presentation from here: http://blogs.egu.eu/divisions/hs/files/2020/05/HSDivMeet2020.pdf

The MacGyver session focuses on novel sensors made, or data sources unlocked, by scientists. All geoscientists are invited to present
- new sensor systems, using technologies in novel or unintended ways
- new data storage or transmission solutions sending data from the field with LoRa, WIFI, GSM, or any other nifty approach
- started initiatives (e.g., Open-Sensing.org) that facilitate the creation and sharing of novel sensors, data acquisition and transmission systems.

Connected a sensor for iPhone to an Arduino or Raspberri Pi? 3D printed an automated water quality sampler? Or build a Cloud Storage system from Open Source Components? Show it! New methods in hydrology, plant physiology, seismology, remote sensing, ecology, etc. are all welcome. Bring prototypes and demonstrations to make this the most exciting Poster Only (!) session of the General Assembly.

This session is co-sponsered by MOXXI, the working group on novel observational methods of the IAHS.

The advancement of hydrological research relies on innovative methods to determine states and fluxes at high spatiotemporal resolution and covering large areas. The emergence of novel measurement techniques has been and will continue to be an important driver for the ability to analyze hydrological processes and to evaluate process-based models. Recent advances in non-invasive techniques, such as cosmic-ray neutron probes, GNSS reflectometry, ground-based microwave radiometry, gamma-ray monitoring and terrestrial gravimetry, allow continuous contactless and integrative measurements of hydrological state variables and fluxes from the field to basin scale. The integration of these approaches with open-access satellite data is boosting the fine-tuning of hydrological models with breakthrough applications in precision farming, forest management, and prediction of droughts, floods and landslides.
We invite contributions dealing with these new types of non-invasive sensing methods, ranging from instrumental aspects, improved algorithms of signal conversion, and data analysis. We also welcome contributions that cover applications of the new methods for investigating hydrological processes, and the integration of non-invasive monitoring data into models from the field to the catchment scale. In addition, we encourage presentations of new data storage or transmission solutions for sending data from the field (such as LoRa, WIFI and GSM) or started initiatives (such as Open-Sensing.org) that facilitate the creation and sharing of novel sensors, data acquisition and transmission systems to generate spatialized hydrological information.

River monitoring remains a challenge for hydrologists and environmental agencies. The expansion of the human population, urbanisation, technological advancements and a changing global climate have put forward an ongoing water management agenda. River streamflow is one of the most crucial hydrological variables in terms of 'basin health' description (from an ecological point of view), and for flood risk management and modelling. However, despite significant efforts on river flow monitoring, long-term, spatially dense monitoring networks remain scarce, stressing the need for innovative solutions dealing with the twin challenges of a changing climate. Emerging innovative methods should be tested and benchmarked under different flow conditions to ensure accurate and consistent results and well-understood measurement uncertainties. Furthermore, these methods must be harmonised for promoting good practices and dissemination over the globe. In this context, this session focuses on:

1) The use of remote sensing approaches for hydrological and morphological monitoring;
2) Real-time acquisition of hydrological variables;
3) Innovative methodologies for measuring/modelling/estimating river stream flows;
4) Measuring the extremes of high and low flows associated with a changing climate;
5) Strategies to quantify and describe hydro-morphological evolution of rivers;
6) New methods to cope with data-scarce environments;
7) Inter-comparison of innovative and classical models and approaches;
8) Quantification of uncertainties; and,
9) Guidelines for hydro-morphological streamflow monitoring.

Contributions are welcome with emphasis on image-velocimetry or other velocity measurement techniques, wetted cross-section retrieval from digital surface models (e.g. computed with multi-media photogrammetry/structure-from-motion, or other bathymetric techniques), and quantification of stream flows and related uncertainties. Additionally, presentations of case studies using innovative sensors, Unmanned Aerial Systems (UASs) and Unmanned Surface Vehicles (USVs), airborne or satellite-based approaches, and traditional in-situ measurements are encouraged. This session is sponsored by the COST Action CA16219, Harmonisation of UAS techniques for agricultural and natural ecosystems monitoring (HARMONIOUS).
Note: This session is complemented by a field-based short-course, SC2.9, offering attendees the opportunity to experience some of these tools and techniques in a river environment.

Instrumentation and measurement technologies are currently playing a key role in the monitoring, assessment and protection of environmental resources. Climate study related experiments and observational stations are getting bigger and the number of sensors and instruments involved is growing very fast. This session deals with measurement techniques and sensing methods for the observation of environmental systems, focusing on water systems and climate.
We welcome contributions about advancements on field measurement approaches, the development of new sensing techniques, as well as the deployment of sensor networks and measurement methods enabling crowdsourced data collection, including innovative low cost sensors. Remote sensing techniques for the monitoring of water resources and/or the related infrastructures are within the scope of this session and welcome.
Studies about signal and data processing techniques targeted to event detection and the integration between sensor networks and large data systems are also very encouraged. Water quantity and quality measurements alongside water characterization techniques are within the scope of this session. This session is also open for all works about an existing system, planning a completely new network, upgrading an existing system, improving streaming data management, and archiving data.
Contributions dealing with the integration of data from multiple sources are solicited, as well as about establishing, maintaining, and managing a fixed network of sensors for water systems and climate.

Geophysical measurements offer important baseline datasets as well as validation for modelling and remote sensing products for cryospheric sciences. Applications include the dynamics of ice-sheets, alpine glaciers and sea ice, changes in snow cover properties of seasonal and permanent snow, snow/ice-atmosphere-ocean interactions, permafrost degradation, geomorphic processes and changes in subsurface materials.

In this session we welcome contributions related to a wide spectrum of geophysical- and in-situ methods, including advances in diverse techniques such as radioglaciology, active and passive seismology, acoustic sounding, GPS/GNSS reflectometry or time delay techniques, cosmic ray neutron sensing, drone applications, geoelectrics and NMR. Contributions may concern field applications as well as new approaches in geophysical/in-situ survey techniques or theoretical advances in the field of data analysis, processing or inversion. Case studies from all parts of the cryosphere such as snow, alpine glaciers, ice sheets, glacial and periglacial environments and sea ice are highly welcome. The focus of the session is to compare experiences in the application, processing, analysis and interpretation of different geophysical and in-situ techniques in these highly complex environments.

This session is offered as a PICO: an engaging presentation format that has been successfully tested for this session during the last three years at EGU. All selected contributions will present their research orally, and then further present their research using interactive screens. This results in rich scientific feedback and is an effective tool for communicating science with high visibility.

This is a joined session - we merged with the former session SM5.5 'Active and passive seismic methods for imaging and monitoring the cryosphere'.


++++++++++++++++++++++++++++ Invited Speaker ++++++++++++++++++++++++++++++++++++

Dustin Schroeder: Observing Evolving Subglacial Conditions with Muti-Temporal Radar Sounding

Public information:
Session topics:
A) Glaciers, Englacial and Subglacial: Schroeder (invited), Rix & Mulvaney et al., Yushkova et al., Jansen et al., Delf et al., Church et al., Pettinelli et al., Kufner et al., Mordret et al., Brisbourne et al., Jones et al., Stevens et al.
B) Sea Ice & Ocean Floors: Jakovlev et al., Schlindwein et al.
C) Ice Rheology: Hellmann et al., Booth et al., Ershadi et al., Martin et al.
D) Snow & Firn: Case et al., Pearce et al., Priestley, Capelli et al., Henkel et al.
E) Permafrost: Maierhofer et al., Limbrock et al., Boaga et al., Lyu et al., Valois et al., Majdanski et al.

Besides our EGU2020: Sharing Geoscience Online text-based chat on Mon, 04 May, 08:30–10:15, we are planning an additional video conference (outside the EGU programme) at the same day starting at 18:00/06:00p.m. In this video conference, our invited speaker Dustin Schroeder will give his talk on ‘Observing Evolving Subglacial Conditions with Mutitemporal Radar Sounding’. We will then open a broader discussion on all different topics and methods of our session.
Time: Mon, 04 May, start: 18:00/06:00p.m. Vienna time (CEST) (= 12:00 New York time)
Place/Link: https://rutgers.webex.com/rutgers/k2/j.php?MTID=tc085b8a9bc24b1c04784c81584672fc4
Session password: YvBGu8jV773 (Global call-in numbers: https://rutgers.webex.com/rutgers/globalcallin.php?MTID=t7ddb8d0ab92b0bd317c7e36862494393 Access code: 192 664 533)

@all authors of this session: It would be great if you can help us a bit in our session planning. Therefore, we would like to ask you to complete the following Doodle survey asap: https://doodle.com/poll/sese8bcs57dcfye5
In this survey we would like to know, if you will be able to
a) upload a display until Thu, 30 April
b) participate during our official EGU2020: Sharing Geoscience Online text-based chat on Mon, 04 May, 08:30–10:15 am
c) participate during our additional video conference on Mon, 04 May, 18:00/6p.m. (please pay attention, time was updated!)
Thank you very much for your help.

This multidisciplinary session invites contributions on the use of methods and tools aimed to obtain reliable stable isotope data in various areas. The number of papers using stable isotopes as a tool has increased enormously in the last years. Though this become a very common technique in many science fields (biogeosciences, atmospheric, environment, ecology, forensics, etc), such datasets are difficult to compare / combine as the data quality is often unknown. Different protocols used in different labs, not optimal use of Reference Materials (RMs), isotope fractionation during sample-preparation and within TCEA peripherals, exchangeable hydrogen and oxygen, different data corrections – these are a few examples of potential pitfalls. Evaluating data quality may be especially difficult for novel methodologies such as atmospheric research (e.g. N2O), applications using matrices with exchangeable Hydrogen, CSIA (e.g. fatty acids, amino acids). The session calls for papers that try to search flaws in analytical methods, in comparison of different datasets produced in different labs/methods, creating protocols and tools for QA/QC, investigation of proper RMs to be used for the fit-for-purpose. This session is a plea for high quality stable isotope data to be applied in many sciences and produce data that can be utilized for the future (this is important considering all efforts in OA journals, datasets, etc) including creating large reference datasets as based on data produced by different labs in areas such as biological species, soils, atmospheric observations, forensics. Often such reference datasets should not be used in any case without a proper QC applied.

This PICO session aims to discuss progress and way forward on the 23 Unsolved Problems in Hydrology (UPH), in general, and, in particular, on transdisciplinary approaches to foster the interface between hydrology and society.
The International Association of Hydrological Sciences (IAHS), in collaboration with the Hydrology Divisions of EGU and AGU as well as the IAH, have recently called for compiling a list of unsolved scientific problems in hydrology that would invigorate research in the 21st century. In a public consultation process, a large number of potential science questions were collated, prioritised and synthesised, which resulted in a set 23 UPH (see https://doi.org/10.1080/02626667.2019.1620507). The UPH are articulated around 7 themes: Time variability and change, Space variability and scaling, Variability of extremes, Interfaces in hydrology, Measurements and data, Modelling methods, and Interfaces with society.
Some of the UPH have already been partially studied and recent research may shed light on how to move forward in a more holistic way. A crucial issue is to put together fragmented knowledge to address the questions raised and enhance coherence in hydrological sciences.
The following themes are of interest in this session:
1. Research results that advance the understanding of any of the 23 UPH as well as review of the state of the art of one (or more) of the UPH, pointing towards directions where progress is most promising and reflections on how the community could evaluate if an UPH can be considered solved or not.
2. Co-production of knowledge and policy. What approaches are available to support a fruitful collaboration between hydrological science and practitioners for tackling the real-world challenges of operational hydrology? How do we deal with uncertainty, adaptation, path dependencies but also with aspects of power, inequality and vested interests in these co-production processes? Who are the users of our knowledge, how useful is our knowledge for those societal users.
3. Interdisciplinary collaborations. How do we create the interdisciplinary knowledge needed to address the questions faced by decision-makers and societal stakeholders? What is the role of hydrologists in these processes? What are the mutual expectations of collaborating researchers from different disciplines and from societal stakeholders?

INVITED PICO TALK: Dr. Daniel Loucks, “Solving the 23 Major Mysteries in Hydrology: Who cares and Why?”

Liaising with stakeholders and policy-makers is becoming increasingly important for scientists to turn research into impactful action. In hydrological sciences, this is needed when implementing innovative solutions in areas such as river basin management, water allocation, impact-based hydrological forecasting, flood protection, drought risk management, climate change mitigation, ecohydrology and sustainable environmental solutions, among others.

The science-policy interface is not just as a way to increase the impact of our science, but it is also a scientific subject in itself. It presents several challenges to both scientists and policy-makers. They include understanding the different steps in the policy cycle: from setting the agenda to formulating, adopting, implementing, monitoring and evaluating polices. It is also crucial to know which facts and evidences are most needed at each step, so scientists can provide the best information at the right time and in the best way.

This session provides the opportunity for discussing with policy makers and addressing the necessary skills to facilitate the uptake of science in policy formulation and implementation: how science influences policy and policies impact science? How scientists can provide easily digestible pieces of evidence to policy-makers? What are the key gaps in joining science to feasible policy solutions in the water sector? How can we use knowledge to improve policy, and vice-versa?

We invite contributions that reflect on the needs of scientists and policy makers at different levels, from local, regional to EU and international levels. Hydrologists have long contributed to produce policy briefs and provide government advice on water-related issues. This session focuses on sharing these experiences (successes or failures), case studies, narratives and best practices at different phases of the policy-making process.

Invited speaker: Philippe Quevauviller (Research Programming and Policy Officer, European Commission, DG HOME, Brussels): “Bridging science, policy, industry and practitioners communities and the citizen dimension for enhancing disaster resilience”

This session welcomes abstracts that consider how to observe, model and analyse interactions between human and water, and the effects of social and environmental changes on hydrological systems. It is organised as part of the IAHS Panta Rhei hydrological decade 2013-2022; and focuses on gains in our understanding of dynamic human-water systems.
Examples of relevant areas include:

- Observations of human impacts on, and responses to, hydrological change.
- Interactions of communities with local water resources.
- Hydrological models that include anthropogenic effects.
- Creation of databases describing hydrology in human-impacted systems.
- Data analysis and comparisons of human-water systems around the globe and especially in developing and emerging countries.
- Human interactions with hydrological extremes, i.e. floods and droughts, and water scarcity.
- The role of gender, age, and cultural background in the impacts of hydrological extremes (floods and droughts), risk perception, and during/after crises and emergencies.
- Conflict and cooperation dynamics in transboundary river basins

Public information:
This session welcomes abstracts that consider how to observe, model and analyse interactions between human and water, and the effects of social and environmental changes on hydrological systems. It is organised as part of the IAHS Panta Rhei hydrological decade 2013-2022; and focuses on gains in our understanding of dynamic human-water systems.
Examples of relevant areas include:

- Observations of human impacts on, and responses to, hydrological change.
- Interactions of communities with local water resources.
- Hydrological models that include anthropogenic effects.
- Creation of databases describing hydrology in human-impacted systems.
- Data analysis and comparisons of human-water systems around the globe and especially in developing and emerging countries.
- Human interactions with hydrological extremes, i.e. floods and droughts, and water scarcity.
- The role of gender, age, and cultural background in the impacts of hydrological extremes (floods and droughts), risk perception, and during/after crises and emergencies.
- Conflict and cooperation dynamics in transboundary river basins

Hydrology is a rich multidisciplinary field encompassing a complex process network involving interactions of diverse nature and scales. Still, it abides to core dynamical principles regulating individual and cooperative processes and interactions, ultimately relating to the overall Earth System dynamics. This session focuses on advances in theoretical and applied studies in hydrologic dynamics, regimes, transitions and extremes along with their physical understanding, predictability and uncertainty. Moreover, it welcomes research on dynamical co-evolution, feedbacks and synergies among hydrologic and other earth system processes at multiple spatiotemporal scales. The session further encourages discussion on physical and analytical approaches to hydrologic dynamics ranging from stochastic, computational and system dynamic analysis, to more general frameworks addressing non-ergodic and thermodynamically unstable processes and interactions.
Contributions are welcome from a diverse community in hydrology and the broader physical geosciences, working with diverse approaches ranging from dynamical modelling to data mining, machine learning and analysis with physical understanding in mind.

Good scientific practice requires research results to be reproducible, experiments to be repeatable and methods to be reusable. This is a particular challenge for hydrological research, as scientific insights are often drawn from analysis of heterogeneous data sets comprising many different sources and based on a large variety of numerical models. The available data sets are becoming more complex and constantly superseded by new, improved releases. Similarly, new models and computational tools keep emerging and many are available in different versions and programming languages, with a large variability in the quality of the documentation. Moreover, how data and models are linked together towards scientific output is very rarely documented in a reproducible way. As a result, very few published results in hydrology are reproducible for the general reader.
A debate on good scientific practice is underway, while technological developments accelerate progress towards open and reproducible science. This session aims to advance this debate on open science, collect innovative ways of engaging in open science and showcase examples. It will include new scientific insights enabled by open science and new (combinations of) open science approaches with a documented potential to make hydrological research more open, accessible, reproducible and reusable.

This session should advance the discussion on open and reproducible science, highlight its advantages and also provide the means to bring this into practice. We strongly believe we should focus on the entire scientific process, instead of the results alone, obtained in a currently still rather fragmented way.

This session is organized in line with other Open Science efforts, such as FAIR Your Science.

Despite only representing about 25% of continental land, mountains are an essential part of the global ecosystem and are recognised to be the source of much of the world’s surfaces water supply apart from important sources of other commodities like energy, minerals, forest and agricultural products, and recreation areas. In addition, mountains represent a storehouse for biodiversity and ecosystem services. People residing within mountains or in their foothills represent approximately 26% of the world’s population, and this percentage increases to nearly 40% when considering those who live within watersheds of rivers originated in a mountain range. This makes mountains particularly sensitive to climate variability, but also unique areas for identifying and monitoring the effects of global change thanks to the rapid dynamics of their physical and biological systems.

This session aims to bring together the scientific community doing hydrology research on mountain ranges across the globe to share results and experiences. Therefore, this session invites contributions addressing past, present and future changes in mountain hydrology due to changes in either climate and/or land use, how these changes affect local and downstream territories, and adaptation strategies to ensure the long-term sustainability of mountain ecosystem services, with a special focus on water cycle regulation and water resources generation. Example topics of interest for this session are:

• Sources of information for evaluating past and present conditions (in either surface and/or ground water systems).
• Methods for differentiating climatic and anthropogenic drivers of hydrological change.
• Modelling approaches to assess hydrological change.
• Evolution, forecasting and impacts of extreme events.
• Case studies on adaptation to changing water resources availability.

By accumulating precipitation at high elevations, snow and ice change the hydrologic response of a watershed. Water stored in the snow pack and in glaciers thus represents an important component of the hydrological budget in many regions of the world and a sustainment to life during dry seasons. Predicted impacts of climate change in headwater catchments (including a shift from snow to rain, earlier snowmelt and a decrease in peak snow accumulation) will affect both water resources distribution and water uses at multiple scales, with potential implications for energy and food production.
Our knowledge about snow/ice accumulation and melt patterns is highly uncertain, because of both limited availability and inherently large spatial variability of hydrological and weather data in remote areas at high elevations. This translates into limited process understanding, especially in a warming climate. The objective of this session is to integrate specialists focusing on snow accumulation and melt within the context of catchment hydrology and snow as a source for glacier ice and melt, hence streamflow. The aim is to integrate and share knowledge and experiences about experimental research, remote sensing and modelling.
Contributions addressing the following topics are welcome:
- experimental research on snowmelt runoff processes and potential implementation in hydrological models;
- development of novel strategies for snowmelt runoff modelling in various (or changing) climatic and land-cover conditions;
- evaluation of remote-sensing (time-lapse imagery, laser scanners, radar, optical photography, thermal and hyperspectral technologies) or in-situ snow products (albedo, snow cover or depth, snow water equivalent) and application for snowmelt runoff calibration, data assimilation, streamflow forecasting or snow and ice physical properties quantification;
- observational and modelling studies that shed new light on hydrological processes in glacier-covered catchments, e.g., impacts of glacier retreat on water resources and water storage dynamic or the application of techniques for tracing water flow paths;
- studies on cryosphere-influenced mountain hydrology, such as landforms at high elevation and their relationship with streamflow, water balance of snow/ice-dominated, mountain regions.

This session is closely linked to session 'Modelling and measuring snow processes across scales', which addresses monitoring and modelling of snow processes across scales.

Public information:
Please check the session materials to see the topic of the session and its organisation: https://meetingorganizer.copernicus.org/EGU2020/sessionAssets/35493/materials.pdf.
Please check the session summary to see the scheduling of displays: https://meetingorganizer.copernicus.org/EGU2020/sessionAssets/35493/summary.pdf.

Water is a strategic issue in the Mediterranean region, mainly because of the scarcity of the available resources, in quantity and/or quality. The Mediterranean climate and the surface hydrology are characterized by a strong variability in time and space and the importance of extreme events, droughts and floods. This irregularity is also met at a lower level in aquifers dynamics. During the last century, modifications of all kinds and intensities have affected surface conditions and water uses. The Mediterranean hydrology is then continuously evolving.

This session intends to identify and analyse the changes in the Mediterranean hydrology, in terms of processes, fluxes, location. It will gather specialists in observation and modeling of the various water fluxes and redistribution processes within the catchments.
Contributions addressing the following topics are welcome:

• Spectacular case studies of rapid changes in water resources;
• Using various sources of information for comparing past and present conditions;
• Differentiating climatic and anthropogenic drivers (including GCM reanalysis);
• Modelling hydrological changes (in surface and/or ground water);
• Impacts of extreme events on water systems.

Annually, various parts of Africa are affected by climate related impacts, such as droughts, flooding etc., to varying degrees of severity. Global and regional hydrological models have recently seen tremendous advances in improved representations of physical processes underpinning these impacts, resulting in better reproductions of observed variables such as streamflow and water extent. As a result, they are increasingly used for predicting socio-economic risks of floods, droughts and water stress in regions around the globe. However, the use of hydroclimatic models for disaster risk reductions in data-sparse regions, while gradually improving, is still limited in comparison.
This session aims to bring together communities working on different strands of African hydrology, climate and other water-related topics, including environmental and food security. We welcome both fundamental and applied research in the areas of hydrological process understanding, flood forecasting and mapping, seasonal forecasting, water resources management, climate impact assessment and societal impacts. Interdisciplinary studies aiming at increasing our understanding of the physical drivers of water-related risks and their impacts in Africa are encouraged. Case studies showcasing practical experiments and innovative solutions in decision making under large uncertainty are welcomed.

Anthropogenic intervention is exerting enormous pressure on natural ecosystems, affecting water quantity and quality, and, as a consequence, threatening socio-economic and human development as described by the UN Sustainable Development Goals. Yet, we still lack a proper understanding of how catchments respond to changing environmental conditions and disturbances. Answering these open questions requires interdisciplinary approaches in combination with novel monitoring methods and modelling efforts.
This session has two key foci: 1) hydrological processes in forested catchments in various climates, and 2) hydrological processes specifically in tropical systems.
Forests are recognized as prime regulators of the hydrological cycle and their change has effects on, for example, energy cycles and ecosystem services they provide. The traditional idea that forest hydrology emphasizes the role of forests and forest management practices on runoff generation and water quality has been broadened in the light of rapid global change. Some of the largest forested areas are located in the tropics and have suffered rapid land-use changes. These tropical systems are still markedly underrepresented in hydrological studies compared to temperate regions, especially concerning long-term observations. This session will bring together studies that will enhance our understanding and stimulate discussions on the impact of global change on forest and tropical hydrological processes at different scales.
We invite field experimentalists and modelers to submit contributions on process-oriented studies that investigate the hydrological cycle in forests and other land uses/land covers, from boreal to tropical regions, including also water quality and ecohydrological aspects.

Agriculture plays a vital role in the socio-economic development. For agricultural production, whether rainfed or using irrigation, water is a key requirement. Therefore, a thorough understanding of the hydrological processes in agricultural lands is essential to address a wide range of issues, including soil moisture condition, crop water requirement, agricultural productivity, water efficiency, soil erosion, and solute transport.
This session is intended to address and advance our understanding of the role of hydrological processes in agricultural lands. Some of the topics and questions of interest are: (1) modelling the impacts of climate change on water balance and agricultural productivity at watershed scale; (2) identification of dominant hydrological factors and how they can be measured locally for improving water supply to crops; (3) effects of irrigation schemes on regional evapotranspiration and soil moisture content; (4) effects of artificial drainage on water regime and solute transport at different spatial scales; (5) aquifer vulnerability to high rates of fertilizer and pesticide applications; (6) multi-process and multi-scale water and energy transitions in agricultural lands; (7) water and energy responses to water-saving practice; and (8) linking hydrological issues with other environmental issues, including removal of natural vegetation, droughts and floods, and soil erosion. We welcome abstracts addressing the above topics or other topics related to hydrological processes in agricultural lands.

A large proportion of the global stream network comprises channels that cease to flow or dry periodically. These systems range from near-perennial rivers with infrequent, short periods of zero flow to rivers experiencing flow only episodically following large rainfall events. Intermittent and ephemeral rivers support a unique high-biodiversity because they are coupled aquatic-terrestrial systems that accommodate a wide range of aquatic, semi-aquatic and terrestrial flora and fauna. Extension and connection of the flowing stream network can affect the quantity and quality of water in downstream perennial rivers. In many arid conditions, they are the main source of fresh water for consumptive use. However, in many places intermittent and ephemeral rivers lack protection and adequate management. There is a clear need to study the hydrology, ecology and biogeochemistry of natural intermittent and ephemeral streams to characterize their flow regimes, to understand the main origins of flow intermittence and how this affects their biodiversity, and to assess the consequences of altered flow intermittency (both increased and decreased) in river systems.
This session welcomes all contributions on the science and management of intermittent and ephemeral streams, and particularly those illustrating:
• current advances and approaches in characterizing and modelling flow intermittency,
• the effects of flow in intermittent streams on downstream perennial streams,
• the factors that affect flowing stream network dynamics
• land use and climate change impacts on flow intermittency,
• links between flow intermittency and biogeochemistry and/or ecology.

Dynamic subglacial and supraglacial water networks play a key role in the flow and stability of ice sheets. The accumulation of meltwater on the surface of ice shelves has been hypothesized as a potential mechanism controlling ice-shelf stability, with ice-shelf collapse triggering substantial increases in discharge of grounded ice. Observations and modelling also suggest that complex hydrological networks occur at the base of glaciers and these systems play a prominent role in controlling the flow of grounded ice. This session tackles the urgent need to better understand the fundamental processes involved in glacial hydrology that need to be addressed in order to accurately predict future ice-sheet evolution and mass loss, and ultimately the contribution to sea-level rise .
We seek contributions from both the modelling and observational communities relating to any area of ice-sheet hydrology. This includes but is not limited to: surface hydrology, melt lake and river formation; meltwater processes within the ice and firn; basal hydrology; subglacial lakes; impacts of meltwater on ice-sheet stability and flow; incorporation of any of these processes into large-scale climate and ice-sheet models.

Snow cover characteristics (e.g. spatial distribution, surface and internal physical properties) are continuously evolving over a wide range of scales due to meteorological conditions, such as precipitation, wind and radiation.
Most processes occurring in the snow cover depend on the vertical and horizontal distribution of its physical properties, which are primarily controlled by the microstructure of snow (e.g. density, specific surface area). In turn, snow metamorphism changes the microstructure, leading to feedback loops that affect the snow cover on coarser scales. This can have far-reaching implications for a wide range of applications, including snow hydrology, weather forecasting, climate modelling, and avalanche hazard forecasting or remote sensing of snow. The characterization of snow thus demands synergetic investigations of the hierarchy of processes across the scales ranging from explicit microstructure-based studies to sub-grid parameterizations for unresolved processes in large-scale phenomena (e.g. albedo, drifting snow).

This session is therefore devoted to modelling and measuring snow processes across scales. The aim is to gather researchers from various disciplines to share their expertise on snow processes in seasonal and perennial snowpacks. We invite contributions ranging from “small” scales, as encountered in microstructure studies, over “intermediate” scales typically relevant for 1D snowpack models, up to “coarse” scales, that typically emerge for spatially distributed modelling over mountainous or polar snow- and ice-covered terrain. Specifically, we welcome contributions reporting results from field, laboratory and numerical studies of the physical and chemical evolution of snowpacks, statistical or dynamic downscaling methods of atmospheric driving data, assimilation of in-situ and remotely sensed observations, representation of sub-grid processes in coarse-scale models, and evaluation of model performance and associated uncertainties.

This session is closely linked to the session 'Snow and ice accumulation, melt, and runoff generation in catchment hydrology', which addresses monitoring and modelling of snow for hydrologic applications.

To construct hydrological models, hypotheses are formulated based on hydrological knowledge. The essence of hydrological model development is the trade-off between model parsimony and adequacy in terms of process representation. The relationship between large quantitative and qualitative data sets across spatial and temporal scales with increasing availability and the way processes are implemented in models is an ongoing discussion.
In this session we welcome contributions on the interaction between data and models with the aim of improving process understanding and representation in their spatio-temporal dynamics.
Potential contributions may include (but not limited to):
(1) Improving model structural adequacy informed by cutting-edge hydrological data and knowledge;
(2) Better representing often neglected processes in hydrological models such as human impacts, river regulations, irrigation, as well as vegetation dynamics;
(3) Improving the characterization of spatio-temporal dynamics of internal and external model fluxes;
(4) Upscaling experimentalists' knowledge from smaller to larger scale by identifying driving forces for spatial patterns;
(5) Better monitoring and seamless modeling of spatial patterns in hydrology and land surface models using distributed earth observations;
(6) The development of novel approaches and performance metrics for evaluating and constraining models in space and time.
(7) How can hydrological models be adapted to be able to extrapolate to changing conditions, including changing vegetation dynamics? (From the initiative of 23 Unsolved Problems in Hydrology, https://doi.org/10.1080/02626667.2019.1620507)
This session is organized as part of the grass-root modelling initiative on "Improving the Theoretical Underpinnings of Hydrologic Models" launched in 2016.

Invited Speakers:

Susan Steele-Dunne from Delft University of Technology on "Advances in using radar to observe vegetation water dynamics"
and
Hylke Beck from Princeton University on "Towards global fully-distributed regionalization of hydrological model parameters."

Earth Systems Models aim at describing the full water- and energy cycles, i.e. from the deep ocean or groundwater across the sea or land surface to the top of the atmosphere. The objective of the session is to create a valuable opportunity for interdisciplinary exchange of ideas and experiences among members of the Earth System modeling community and especially atmospheric-hydrological modelers.
Contributions are invited dealing with approaches how to capture the complex fluxes and interactions between surface water, groundwater, land surface processes, oceans and regional climate. This includes the development and application of one-way or fully-coupled hydrometeorological prediction systems for e.g. floods, droughts and water resources at various scales. We are interested in model systems that make use of innovative upscaling and downscaling schemes for predictions across various spatial- and temporal scales. Contributions on novel one-way and fully-coupled modeling systems and combined dynamical-statistical approaches are encouraged. A particular focus of the session is on weakly and strongly coupled data assimilation across the different compartments of the Earth system for the improved prediction of states and fluxes of water and energy. Merging of different observation types and observations at different length scales is addressed as well as different data assimilation approaches for the atmosphere-land system, the land surface-subsurface system and the atmosphere-ocean system. The value of different measurement types for the predictions of states and fluxes, and the additional value of measurements to update states across compartments is of high interest to the session. We also encourage contributions on use of field experiments and testbeds equipped with complex sensors and measurement systems allowing compartment-crossing and multi-variable validation of Earth System Models.

Stable and radioactive isotopes as well as other natural and artificial tracers are useful tools to fingerprint the source of water and solutes in catchments, to trace their flow pathways or to quantify exchanges of water, solutes and particulates between hydrological compartments. Papers are invited that demonstrate the application and recent developments of isotope and other tracer techniques in field studies or modelling in the areas of surface / groundwater interactions, unsaturated and saturated zone, rainfall-runoff processes, nutrient or contaminant export, ecohydrology or other catchment processes.

Land use and climate change as well as legal requirements (e.g. the EU Water Framework Directive) pose new challenges for the assessment and sustainable management of surface water quality at the catchment scale. Sources and pathways of nutrients and pollutants have to be characterized to understand and manage the impacts of their enrichment in river systems. Additionally, water quality assessment needs to cover the chemical and ecological status to link the hydrological view to aquatic ecology.
Models can help to optimize monitoring schemes. However, insufficient temporal and/or spatial resolutions, a short duration of observations or not harmonized analytical methods restrict the data base for model application. Moreover, model-based water quality calculations are affected by errors in input data, model errors, inappropriate model complexity and insufficient process knowledge or implementation. Therefore there is a strong need for advances in water quality models and to quantify and reduce uncertainties in water quality predictions. Additionally, models should be capable of representing changing land use and climate conditions, which is a prerequisite to meet the increasing needs for decision making.

This session aims to bring scientist together who work on experimental as well as on modelling studies to improve the prediction and management of water quality constituents (with the focus on nutrients, organic matter, algae or sediments) at the catchment scale. Contributions are welcome that cover the following issues:

- Experimental and modelling studies on the identification of sources, hot spots and pathways of nutrients and pollutants at the catchment scale
- New approaches to develop efficient water quality monitoring schemes
- Innovative monitoring strategies that support both process investigation and model performance
- Advanced modelling tools integrating catchment as well as in-stream processes
- Observational and modelling studies at catchment scale that relate and quantify water quality changes to changes in land use and climate
- Measurements and modelling of abiotic and biotic interaction and feedback involved in the transport and fate of nutrients and pollutants at the catchment scale
- Catchment management: pollution reduction measures, stakeholder involvement, scenario analysis for catchment management

Surface water quality deterioration is typically assessed and managed at the catchment scale. Management decisions rely on process knowledge and understanding of cause-effect relationships to be effective. However, the dynamics of solute and particulate concentrations integrate a multitude of hydrological and biogeochemical processes interacting at different temporal and spatial scales, which are difficult to assess using local field experiments. Hence, time series of water quality observed at the outlet of catchments can be highly beneficial to understand these processes. Long-term, high-frequency as well as multiple-site datasets can be used to inform experimental and modelling studies and formulate hypotheses on dominant ecohydrological and geochemical processes moving “from pattern to process”. Recent advances in this field have used concentration-discharge relationships to infer the interplay between hydrological and biogeochemical controls, both in the terrestrial part of catchments and in the river network. Long-term time series of nutrient input-output relationships help understand nutrients legacy effects and catchments response times. High-frequency observations allow understanding the fine structure of concentration dynamics, including flowpaths and their age distribution during runoff events and ecological controls on diel cycles. When multiple catchments are monitored, it is possible to relate metrics from concentration time series to catchment descriptors.
This session aims to bring together studies using data-driven analysis of river concentration time series to infer solute and particulate export mechanisms. We strongly encourage studies that use findings from data-driven analysis to build conceptual and process-based models. Presentations of the following topics are invited:
- Interpretation of C-Q relationships from storm events to long-term shifts
- Long-term changes of nutrient inputs, outputs and nutrient stoichiometry
- Role of hydrological extremes such as the recent Central European droughts in long-term trajectories of nutrient exports
- Co-variance of solute and particulate concentrations and their ecohydrological controls
- Instream processes and river network effects on nutrient load and concentration dynamics
- Utilizing time series of compound-specific isotopic fingerprints
- Time series analysis of emerging contaminants such as pesticides or micropollutants

Bayesian approaches have become increasingly popular in water quality modelling, thanks to their ability to handle uncertainty comprehensively (data, model structure and parameter uncertainty) and as flexible statistical and data mining tools. Furthermore, graphical Bayesian Belief Networks can be powerful decision support tools that make it relatively easy for stakeholders to engage in the model building process. The aim of this session is to review the state-of-the-art in this field and compare software and procedural choices in order to consolidate and set new directions for the emerging community of Bayesian water quality modellers.

In particular, we seek contributions from water quality research that use Bayesian approaches to, for example but not exclusively:
• quantify the uncertainty of model predictions
• quantify especially model structural error through, for example, Bayesian Model Averaging or structural error terms
• address the problem of scaling (e.g. disparity of scales between processes, observations, model resolution and predictions) through hierarchical models
• model water quality in data sparse environments
• compare models with different levels of complexity and process representation
• use statistical emulators to allow probabilistic predictions of complex modelled systems
• integrate prior knowledge, especially problematizing the choice of Bayesian priors
• produce user-friendly decision support tools using graphical Bayesian Belief Networks
• involve stakeholders in model development and maximise the use of expert knowledge
• use machine-learning and data mining approaches to learn from large, possibly high-resolution data sets.

Identification of contaminant sources, transport and fate at the catchment scale is crucial to evaluate and predict human and environmental impacts. Land management practice and water quality protection suffer from the threat posed by mining and agriculture activities. Historical and contemporary mining activities generate significant volumes of contaminated waste that can have wide-ranging implications, including potential lethal and sub-lethal effects on aquatic biota, adverse effects on surface waters used for drinking water and irrigation, and overall degradation of water bodies used for recreation and other purposes. Furthermore, contaminants may originate from various sources related to agriculture activities including cultivation, aquaculture, livestock and dairy farms and related food-processing industries.
Ming and agricultural contaminants can be dispersed in river catchments by a variety of physical, chemical and biological pathways and processes. The complexity and variability of these processes are still seeking a complete understanding .This session aims to characterize and quantify: (1) source areas contributing to contaminant mass dispersion, (2) transport processes mobilizing contaminants from their source areas to and through affected water bodies including streams, rivers, lakes, wetlands, and groundwater, (3) biogeochemical processes attenuating and/or transforming contaminants, (4) the interactions of contaminants with biota and ecosystems, and (5) the use of hydro(geo)chemical and stable isotope tracers to quantify (agro)contaminant sources and transport. Submissions from a variety of subfields are welcome, including research into mine water treatment and mine waste remediation practices, and biogeochemical modelling of contaminant at the catchment scale. We also welcome submissions that focus on a variety of contaminant types including, but not limited to, metals, metalloids, rare earth elements, sulfate, pesticides and nutrients.

A large number of pathogens, micropollutants and their transformation products (veterinary and human pharmaceuticals, personal care products, pesticides and biocides, chlorinated compounds, heavy metals) pose a risk for soil, groundwater and surface water. The large diversity of compounds and of their sources makes the quantification of their occurrence in the terrestrial and aquatic environment across space and time a challenging task. Regulatory monitoring programmes cover a small selection out of the compound diversity and quantify these selected compounds only at coarse temporal and spatial resolution. Carefully designed monitoring however allows to detect and elucidate processes and to estimate parameters in the aquatic environment. Modeling is a complementary tool to generalize measured data and extrapolate in time and space, which is needed as a basis for scenario analysis and decision making.

This session invites contributions that improve our quantitative understanding of the sources and pathways, mass fluxes, the fate and transport of micropollutants and pathogens in the soil-groundwater-river continuum. Topics cover:
- Novel sampling and monitoring concepts and devices
- New analytical methods, new detection methods for DNA, pathogens, micropollutants, non-target screening
- Experimental studies and modelling approaches to quantify diffuse and point source inputs
- Novel monitoring approaches such as non-target screening as tools for improving processes understanding and source identification such as industries
- Comparative fate studies on parent compounds and transformation products
- Diffuse sources and (re-)emerging chemicals
- Biogeochemical interactions and impact on micropollutant behaviour

Hydrological extremes (droughts and floods), have major impacts on society and ecosystems and are expected to increase in frequency and severity with climate change. Although both at the extreme end of the hydrological spectrum, floods and droughts are governed by different processes, which means that they operate on different spatial and temporal scales and that different analysis methods and indices are needed to characterise them. But there are also many similarities and links between the two extremes that are increasingly being studied.
This general session on hydrological extremes aims to bring together the two communities in order to learn from the similarities and differences between flood and drought research. We aim to increase the understanding of the governing processes of both hydrological extremes, find robust ways of modelling and analysing floods and droughts, assess the influence of global change (including climate change, land use change, and other anthropogenic influences) on floods and droughts, and study the socio-economic and environmental impacts of hydrological extremes. We welcome submissions of insightful studies of floods or droughts, and especially encourage abstracts that cover both extremes.
This session is jointly organised by the Panta Rhei Working Groups “Understanding Flood Changes”, “Changes in Flood Risk”, and “Drought in the Anthropocene” and will further stimulate scientific discussion on change detection and attribution of hydrological extremes and the feedbacks between hydrological extremes and society. The session is linked to the European Low Flow and Drought Group of UNESCO´s IHP-VIII FRIEND-Water Program, which aims to promote international drought research. Excellent submissions of early-career researchers that are deemed important contributions to the session topics will be classified as solicited talks, as a "label of excellence".

Public information:
The discussion of the displays in this session will be carried out in ten blocks of 20 minutes.
All displays have been assigned to one of the blocks. Please note that not all authors are able to participate, and so the timing may fluctuate a little.

08:30 Welcome and structure of the session
08:33-08:55 Block 1 - Displays D54 to D57: Niko Wanders (invited), Abraham Gibson, Chunyu Dong, Hoori Ajami
08:55-09:15 Block 2 - Displays D58 to D61: Vimal Mishra, Oldrich Rakovec, Mathilde Erfurt, Manuela Brunner (invited)
09:15-09:35 Block 3 - Displays D62 to D65: Gabriele Villarini, Ralf Merz, Yuan Yang, Ricardo Mantilla
09:35-09:55 Block 4 - Displays D66 to D69: Jonathan Goodall, Maurizio Mazzoleni, Gauranshi Raj Singh, Rajendran Vinnarasi
09:55-10:15 Block 5 - Displays D70 to D74: Surendra Kumar Mishra, Hans Van de Vyver, Shuang Zhu, Xing Yuan, Liu Liu

10:15-10:45 Coffee break (grab a hot drink from your kitchen!)

10:45 Welcome back
10:48-11:10 Block 6 - Displays D75 to D78: Jiabo Yin, Ioanna Stamataki, Liliang Ren, Johannes Laimighofer
11:10-11:30 Block 7 - Displays D79 to D82: Josie Baulch, Gebremedhin Gebremeskel Haile, Jan Řehoř, Sigrid Jørgensen Bakke
11:30-11:50 Block 8 - Displays D83 to D86: Yves Tramblay, Harry West, Kunal Bhardwaj, Haider Ali
11:50-12:10 Block 9 - Displays D87 to D90: Yusuke Satoh, Cha Zhao, Simon Parry, Kevin Mátyás
12:10-12:30 Block 10 - Displays D91 to D94: Bentje Brauns, Marc Scheibel, Ho Jun Kim, Ammara Nusrat
12:30 Closing remarks

Extreme hydrological events disasters such as droughts, floods and storms lead to the most devastating natural in terms of casualties and economic losses. In the context of current global warming, there is a high uncertainty on the observed trends and projected changes in extremes at a global scale. Extreme events that occurred in the past play here an important role as they enable us to investigate the dynamics of extremes under natural climate variability beyond the instrumental period. The main goal of this session is to bring together scientist, scholar and engineers that explore the variability and controlling mechanisms of past hydrological extremes on decadal to millennial time-scales based on different historical and natural archives such as tree-rings, speleothems, lacustrine and marine sediments and ice cores. We also welcome contributions that integrate both, proxy data and climate modelling to understand the external and internal forcing controlling the hydrological cycle. We also invite contributions that explore new statistical modelling approaches aiming to quantitatively assess the climate drivers of the non-stationary behaviours of extreme events frequency and intensity.

The space-time dynamics of floods are controlled by atmospheric, catchment, river system and anthropogenic processes and their interactions. The natural oscillatory behaviour of floods (between flood-rich and flood-poor periods) superimpose with anthropogenic climate change and human interventions in river morphology and land uses. In addition, flood risk is further shaped by continuous changes in exposure and vulnerability. Despite more frequent exploratory analyses of the changes in spatio-temporal dynamics of flood hazard and risk, it remains unclear how and why these changes are occurring. The scope of this session is to report when, where, how (detection) and why (attribution) changes in the space-time dynamics of floods occur. Of particular interest is what drivers are responsible for observed changes. Presentations on the impact of climate variability and change, land use changes and morphologic changes in streams, as well as on the role of pre-flood catchment conditions in shaping flood hazard and risk are welcome. Furthermore, contributions on the impact of socio-economic and structural factors on past and future risk changes are invited. This session is jointly organised by the Panta Rhei Working Groups “Understanding Flood Changes” and “Changes in Flood Risk”. The session will further stimulate scientific discussion on flood change detection and attribution. Specifically, the following topics are of interest for this session:

- Decadal oscillations in rainfall and floods

- Process-informed extreme value statistics

- Interactions between spatial rainfall and catchment conditions shaping flood patterns

- Detection and attribution of flood hazard changes: atmospheric drivers, land use controls and river training, among others

- Changes in flood risk: urbanisation of flood prone areas; implementation of risk mitigation measures, such as natural water retention measures; changes of economic, societal and technological drivers; flood damages; flood vulnerability; among others.

- Future flood risk changes and adaptation and mitigation strategies

Catchments are organised systems: their behaviour mostly results of typical patterns of topography, soils, and vegetation and this organisation of catchment components controls the storage and release of water and nutrients at the short and medium term. The behaviour of catchments also shows longer-term dependencies to storage in aquifers, lakes and man-made reservoirs, which significantly affects the variability of hydrological response in time, across multiple spatial and temporal scales.

Understanding catchment organization and assessing its memory is critical for (i) creating catchment models that balance necessary complexity with possible simplicity, (ii) understanding the degree of similarity between catchments, with the prospect of developing hydrological theories that are transferable in space and/or time, (iii) understanding and predicting the potential impact of environmental changes on hydrological response in a changing environment, and (iv) better managing and operating water resources systems, water quality plans or flood protection systems.

This session invites contributions on:
. the degree of model complexity needed to characterize catchment processes and response,
. new approaches to assess the memory of catchments,
. multi-catchment analysis of the degree of similarity in climate, landscape, and hydrology,
. methods and case studies identifying controls on the residence time of water and solutes in contrasting landscapes,
. the relative effects of climate, landscape and human interventions on catchment response,
. methods assessing the impact of land use change on catchment response,
. the uncertainties involved in the identification of dominating processes and hydrologic response behaviour,
. studies of historic climate variability to quantify catchment memory,
. regionalisation of catchment memory through catchment organisation description and its underlying organizing principle,
. the measure (i.e., quantification) of human impacts and the consequent change on catchment response behaviour and similarity,
. case studies on flood-rich/drought-rich and flood-poor/drought-poor sequences,
. methods exploiting catchment memory to improve hydrological models, discharge and nutrient prediction, and evaluation of water resources systems.

Note that from the point of view of the 23 Unsolved Problems in Hydrology initiative, this session will contribute to addressing six problems: n°5, n°6, n°8, n°9, n°14 and n°22.

Public information:
co-convener (PoliTO, Italy)

In the current context of global change, assessing the impact of climate variability and changes on hydrological systems and water resources is increasingly crucial for society to better-adapt to future shifts in water resources as well as extreme conditions (floods and droughts). However, hitherto, important sources of uncertainties have been neglected in forecasting climate impacts on hydrological systems, especially uncertainties associated with internal/natural climate variability, whose contribution to near-future changes could be as important as forced anthropogenic climate changes at the regional scales. Internal climate modes of variability (e.g. ENSO, NAO, AMO) and their impact on the continent are not properly reproduced in the current global climate models, leading to large underestimations of decadal climate and hydroclimatic variability at the global scale. At the same time, hydrological response strongly depends on catchment properties, whose interactions with climate variability are little understood at the decadal timescales. These factors altogether reduce significantly our ability to understand long-term hydrological variability and to improve projection and reconstruction of future and past hydrological changes on which improvement of adaption scenarios depends.
We welcome abstracts capturing recent insights for understanding past or future impacts of large-scale climate variability on hydrological systems and water resources as well as newly developed projection and reconstruction scenarios. Results from model intercomparison studies are encouraged.

Public information:
Dear all,

We hope that you are all well, and ready to participate to the EGU 2020 “sharing geoscience online”.
Our session "HS2.4.6/CL2.29/NH1.21: Understanding the links between hydrological variability and internal/natural climate variability" is scheduled tomorrow (Thursday 07) at 10:45-12:30 (CET time).
As you might have noticed in the last days, chairing the online chat requires some managements. With the convener team, we therefore agreed on an organisation plan to enable everyone to present their displays, and discuss it smoothly with the session participants.

First, we would appreciate if you could upload your presentation materials as soon as possible. Because there is not much time per presentation in the chats, participants are reviewing materials in advance of the scheduled sessions, in order to maximise discussion time.

If the first author of your display will not be available, we request that you let us know in advance, who is attending, so we can be sure all expected presenters are online.

When posting your questions, as well as replying, we recommend you begin your questions/answers with @1stAuthorName (e.g. in my case @Bastien). This will make sure that the question/answer is addressed to the right correspondent.

Below are some information on the conduct of our session:

i) We will go through ONLY the presentations which have uploaded materials for displays, and we will follow the order provided on the session programme;

ii) After a brief introduction, we will give 10 minutes to all participants to look through the different displays;

iii) We will then call each author, who will have 2-3 minutes to tell us about their work. As this is not that easy, we strongly recommend you to prepare few highlights (context + bullet points; max. 6 sentences) in advance. So, you can just paste it at the time.

iv) We then will allow 2-3 minutes for questions to each author. Again, we recommend you to prepare any questions for the other authors in advance.

v) Finally, we will thank all the participants, and call for online comments on the website.
We hope to “see” you tomorrow morning, and we hope this will be a nice experience for everyone.

To help with this, we would appreciate if you could upload your material as soon as you can. Bear in mind that it can be updated at anytime.

Note that the time allocated to the presentation and questions might have to be adjusted tomorrow, depending on the final number of displays

Best Regards,
Bastien, Jean-Philippe, Katie and Nicolas

Estimates of water availability and flooding risks remain one of the central scientific and societal challenges of the 21st century. The complexity of this challenge arises particularly from transient boundary conditions: Increasing atmospheric greenhouse gas concentrations lead to global warming and an intensification of the water cycle and finally to shifts in the temporal and spatial distribution of precipitation and terrestrial water availability. Likewise, large-scale land use changes impact and alter regional atmospheric circulation, thereby local precipitation characteristics and again terrestrial water availability. Also the feedbacks between the interlinked terrestrial and atmospheric processes on different spatial and temporal scales are still poorly understood.
This session therefore invites contributions addressing past, present and prospective changes in regional hydrological behaviour due to either (or joint) climate- and/or land use changes. We especially welcome contributions on the development of novel methods and methodologies to quantify hydrological change. Further aspects of this topic comprise particularly:

- Robustness of hydrological impact assessments based on scenarios using downscaled climate model – hydrology model modelling chains.
- Quantification of regional land use change predictions and impact of past, present and future land use changes on water and energy fluxes in meso- to large-scale catchments.
- Joint or coupled modelling of water and energy fluxes between the atmosphere and the land surface/subsurface and analyses of feedback mechanisms.
- Climate change/land use change signal separation techniques and quantification of future land use change vs. climate change induced hydrological change.
- Adequate handling of climate change and land use change data and their uncertainty for the forcing of hydrological models.
- Case studies of regional hydrological behaviour in climate sensitive and flood or drought prone regions worldwide.

Public information:
We as convenors decided to conduct a telecon/videocon via the BigBlueBottom system, which is hosted at a server of the University of Potsdam. Hence, the high data security standards of Germany are in effect on this server. Another advantage of this system is that it can be accessed via the browser so that you do not need to download any software. The necessary link is sent around to all session authors and can be requested from two of the convenors, Stefan Hagemann and Axel Bronstert. During the videocon, micros and cameras of attendees should be usually switched off. Micro and camera should only be switched on for the moderator and the presenter as well as for the one who is providing a comment or question.

To best organize our BBB session, we will carry out the one presentation (display) at the time.
Each presenter has 2 Min. to shortly present his display and may show 1 slide. Then, there will be 5 Min. time to discuss the corresponding display (Hence, displays should be looked at in advance).

Do not try to give a full presentation in these 2 Min., just give a SHORT introduction and highlight the main points. After this short introduction to the presentation, the floor is now open for comments.
If there are no comments, we will move to the next display. Hence, the timing for the sequence of displays to be presented is just a general sketch.

Currently, we have the confimation for 15 displays to be presented. Thus, instead of having two separate sessions on the original oral and poster presentations, we will have one BBB session starting at 8:30 Vienna time. The sequence of displays will be in accordance to their appearance in the EGU session programme
This will take about 2 hours.

Session time, Fr 8 May 2020, 8:30-11:00 (may be extended if more dislays are uploaded and presented)

Global, continental, and other large-scale hydrological research is very important in many different contexts. Examples include; increasing understanding of the climate system and water cycle, assessment of water resources in a changing environment, hydrological forecasting, and water resource management.

We invite contributions from across the atmospheric, meteorological and hydrological communities. In particular, we welcome abstracts that address advances in:

(i) understanding and predicting the current and future state of our global and large scale water resources;

(ii) use of global earth observations and in-situ datasets for large scale hydrology and data assimilation techniques for large scale hydrological models;

(iii) understanding and modelling of extremes: like droughts and floods.

(iv) representing and evaluating different components of the terrestrial water cycle fluxes and storages (e.g. soil moisture, snow, groundwater, lakes, floodplains, evaporation, river discharge) and their impact on current and future water resources and atmospheric modelling.

(v) synthesis studies assembling knowledge gained from smaller scales (e.g. catchments or hillslope) to advance our knowledge on process understanding needed for the further development of large scale models and to identify large scale patterns and trends.

Large and diverse samples of catchments can provide generalisable insights that improve the understanding of hydrological processes beyond findings from single catchments. This session provides the opportunity to showcase recent data- and model-based efforts on large-sample hydrology, which advance the characterisation, understanding and modelling of hydrological diversity. We welcome abstracts from a wide range of fields, including catchment hydrology, land-surface modelling, eco-hydrology, groundwater hydrology and hydrometeorology, which seek to explore:

1. Identification and characterisation of dominant hydrological processes: what is the importance and interplay of landscape attributes for hydrological processes and signatures? How can this interplay be characterised with limited data?
2. Generalisation across spatial scales: how can we use large samples of catchments to refine process understanding and modelling at the regional to global scale?
3. Hydrological similarity and catchment classification: how can information be transferred between catchments?
4. Development of new large-sample data sets, as well as quantification and synthesis of data quality and uncertainty in existing data
5. Human intervention, climate change, and land cover changes: how can these processes be accounted for in large-sample studies?
6. Revisiting hypotheses testing: testing the generality of existing hypotheses (particularly those originally formulated on small samples of catchments) using large samples

We encourage abstracts addressing any of these challenges, in particular those aiming at reducing geographical gaps (i.e., contributing to a more balanced spatial distribution of large-sample data sets) and making use of global data sources (e.g., remote-sensed data or re-analyses) to facilitate comparison between catchments from different parts of the globe.

In addition to this session, there will be a splinter meeting to discuss and coordinate the production of large-sample data sets. Following a similar meeting at EGU 2018 and 2019, it will be entitled “Large sample hydrology: facilitating the production and exchange of data sets worldwide” - see the final programme for location and timing.

The session and the splinter meeting are organised as part of the Panta Rhei Working Group on large-sample hydrology.

Since early work on the assessment of global, continental and regional-scale water balance components, many studies use different approaches including global models, as well as data-driven approaches that ingest in-situ or remotely sensed observations or combination of these. They attempted to quantify water fluxes (e.g. evapotranspiration, runoff/discharge, groundwater recharge) and water storages on the terrestrial part of the Earth, either as total estimates (e.g. from GRACE satellites) or in separate compartments (e.g. water bodies, snow, soil, groundwater). In addition, more and more attention is given to uncertainties that stem from forcing datasets, model structure, parameters and combinations of these. Current estimates in literature show that flux and storage calculations differ considerably due to the methodology and datasets used such that a robust assessment of global, continental and regional water balance components is challenging.
This session is seeking for contributions that are focusing on the:
i. past/future assessment of water balance components (fluxes and storages) such as precipitation, river discharge to the oceans (and/or inland sinks), evapotranspiration, groundwater recharge, water use, changes in terrestrial water storage or individual components at global, continental and regional scales,
ii. application of innovative explorative approaches undertaking such assessments – through better use of advanced data driven, statistical approaches and approaches to assimilate (or accommodate) remote sensing datasets for improved estimation of terrestrial water storages/fluxes,
iii. analysis of different sources of uncertainties in estimated water balance components,
iv. examination and attribution of systematic differences in storages/flux estimates between different methodologies, and/or
v. applications/consequences of those findings such as sea level rise and water scarcity.
We encourage submissions using different methodological approaches. Contributions could focus on any of the water balance components or in an integrative manner with focus on global, continental or regional scale applications. Assessments of uncertainty in past/future estimates of water balance components and their implications are highly welcome.

The purpose of this session is to: (1) showcase the current state-of-the-art in global and continental scale natural hazard risk science, assessment, and application; (2) foster broader exchange of knowledge, datasets, methods, models, and good practice between scientists and practitioners working on different natural hazards and across disciplines globally; and (3) collaboratively identify future research avenues.
Reducing natural hazard risk is high on the global political agenda. For example, it is at the heart of the Sendai Framework for Disaster Risk Reduction and the Warsaw International Mechanism for Loss and Damage Associated with Climate Change Impacts. In response, the last 5 years has seen an explosion in the number of scientific datasets, methods, and models for assessing risk at the global and continental scale. More and more, these datasets, methods and models are being applied together with stakeholders in the decision decision-making process.
We invite contributions related to all aspects of natural hazard risk assessment at the continental to global scale, including contributions focusing on single hazards, multiple hazards, or a combination or cascade of hazards. We also encourage contributions examining the use of scientific methods in practice, and the appropriate use of continental to global risk assessment data in efforts to reduce risks. Furthermore, we encourage contributions focusing on globally applicable methods, such as novel methods for using globally available datasets and models to force more local models or inform more local risk assessment.
At various scales from global to local, many efforts on the collection and use of loss data related to natural hazards (e.g. cyclone, earthquake, flood, wildfire) as well as open datasets have been made in recent years. The integration of these socioeconomic loss databases and open datasets for loss and risk assessment allow for effective use for both science and policy, and to create a community linking academia, government and insurance.
We also encourage you to submit a manuscript to the NHESS special issue on Global- and continental-scale risk assessment for natural hazards (https://www.nat-hazards-earth-syst-sci.net/special_issue966.html). Deadline for submissions to the special issues is 31 December 2019.

Public information:
Public information:
The discussion of the displays in this session will be carried out in five blocks of 20 minutes. The authors who have indicated that they will present their Displays have been assigned to one of the blocks, and the time-schedule is as follows:
14:00-14:05: welcome and structure of the session
14:05-14:25: Finn Løvholt, Adrien Pothon, Krescencja Glapiak, Svetlana Stripajova
14:25-14:45: Jana Sillmann, Gaby Gründemann, Dominik Paprotny, Edwin Sutanudjaja
14:45-15:05: Oliver Wing (sollicited), Jerom Aerts, Dirk Eilander, Viet Dung Nguyen
15:05-15:25: Robert McCall, Samuel Eberenz, John Hillier, Maria Chertova
15:25-15:45: Claudia Wolff, Jacopo Margutti, Paola Salvati, Sara Lindersson
15:45: Closing remarks

Hydroinformatics has emerged over the last decades to become a recognised and established field of independent research within the hydrological sciences. Hydroinformatics is concerned with the development and hydrological application of mathematical modelling, information technology, systems science and computational intelligence tools. We also have to face the challenges of Big Data: large data sets, both in size and complexity. Methods and technologies for data handling, visualization and knowledge acquisition are more and more often referred to as Data Science.

The aim of this session is to provide an active forum in which to demonstrate and discuss the integration and appropriate application of emergent computational technologies in a hydrological modelling context. Topics of interest are expected to cover a broad spectrum of theoretical and practical activities that would be of interest to hydro-scientists and water-engineers. The main topics will address the following classes of methods and technologies:

* Predictive and analytical models based on the methods of statistics, computational intelligence, machine learning and data science: neural networks, fuzzy systems, genetic programming, cellular automata, chaos theory, etc.
* Methods for the analysis of complex data sets, including remote sensing data: principal and independent component analysis, time series analysis, information theory, etc.
* Specific concepts and methods of Big Data and Data Science
* Optimisation methods associated with heuristic search procedures: various types of genetic and evolutionary algorithms, randomised and adaptive search, etc.
* Applications of systems analysis and optimisation in water resources
* Hybrid modelling involving different types of models both process-based and data-driven, combination of models (multi-models), etc.
* Data assimilation and model reduction in integrated modelling
* Novel methods of analysing model uncertainty and sensitivity
* Software architectures for linking different types of models and data sources

Applications could belong to any area of hydrology or water resources: rainfall-runoff modelling, flow forecasting, sedimentation modelling, analysis of meteorological and hydrologic data sets, linkages between numerical weather prediction and hydrologic models, model calibration, model uncertainty, optimisation of water resources, etc.

Citizen Observatories, crowdsourcing, and innovative sensing techniques are used increasingly in water resources monitoring, especially when dealing with natural hazards. These innovative opportunities allow scientists to benefit from citizens’ involvement, by providing key local information for the identification of natural phenomena. In this way new knowledge for monitoring, modelling, and management of water resources and their related hazards is obtained.
This session is dedicated to multidisciplinary contributions, especially those that are focused on the demonstration of the benefit of the use of Citizen Observatories, crowdsourcing, and innovative sensing techniques for monitoring, modelling, and management of water resources.
The research presented might focus on, but not limited to, innovative applications of Citizen Observatories, crowdsourcing, innovative and remote sensing techniques for (i) water resources monitoring; (ii) hazard, exposure, vulnerability, and risk mapping; (iii) development of disaster management and risk reduction strategies. Research studies might also focus on the development of technology, modelling tools, and digital platforms within research projects.
The session aims to serve a diverse community of research scientists, practitioners, end-users, and decision-makers. Submissions that look into issues related to the benefits and impacts of innovative sensing on studies of climate change, anthropogenic pressure, as well as ecological and social interactions are highly desired. Early-stage researchers are strongly encouraged to present their research