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

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.

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

Society today demands sustainable technical solutions that reconcile the needs of society with those of nature . These solutions must coordinate between different and often competing demands within a sub-system (irrigation, ecological flow, power generation) and the variety of different uses of environmental resources across systems (e.g., power from water, wind, sun, or waves). The short term variability of precipitation, wind speed, sunshine, and other for environmental resources create a need for complex decisions to be taken in real time. Advances in real-time automatic control will play an essential role in making this possible. Moreover, while one might debate whether or not stationarity is dead, it is clear that fully deterministic models cannot cope with the connected world of today. The complex interactions of the randomness in the availability and quality of different resources calls out for an at least partially stochastic modelling approach.
We particularly invite contributions on:
• Stochastic modelling and control;
• Real-time control of environmental systems;
• Real-time monitoring and control of water quality;
• Real-time control of rural water systems;
• Real-time control of urban water systems.

The session is associated with Panta Rhei working group ``Natural and man-made control systems in water resources''.

Machine learning (ML) is now widely used across the Earth Sciences and especially its subfield deep learning (DL) has recently enjoyed increased attention in the context of Hydrology. The goal of this session is to highlight the continued integration of ML, and DL in particular, into traditional and emerging Hydrology-related workflows. Abstracts are solicited related to novel theory development, novel methodology, or practical applications of ML and DL in Hydrology. This might include, but is not limited to, the following:

(1) Identifying novel ways for DL in hydrological modelling.
(2) Testing and examining the usability of DL based approaches in hydrology.
(3) Improving understanding of the (internal) states/representations of DL models.
(4) Integrating DL with traditional hydrological models.
(5) Creating an improved understanding of the conditions for which DL provides reliable simulations. Including quantifying uncertainty in DL models.
(6) Clustering and/or classifying hydrologic systems, events and regimes.
(7) Using DL for detecting, quantifying or cope with nonstationarity in hydrological systems and modeling.
(8) Deriving scaling relationships or process-related insights directly from DL.
(8) Using DL to model or anticipate human behavior or human impacts on hydrological systems.
(10) DL based hazard analysis, detection/mitigation, event detection, etc.
(11) Natural Language Processing to analyze, interpret, or condense hydrologically-relevant peer-reviewed literature or social media data or to assess trends within the discipline.

Many environmental and hydrological problems are spatial or temporal, or both in nature. Spatio-temporal analysis allows identifying and explaining large-scale anomalies which are useful for understanding hydrological characteristics and subsequently predicting hydrological events. Temporal information is sometimes limited; spatial information, on the other hand has increased in recent years due technological advances including the availability of remote sensing data. This development has motivated new research efforts to include data in model representation and analysis.

Statistics are in wide use in hydrology for example to estimate design events, forecast the risk and hazard of flood events, detect spatial or temporal clusters, model non-stationarity and changes and many more. Statistics are useful in the case when only few data are available but information for very rare events (extremes) or long time periods are needed. They are also helpful to detect changes and inconsistencies in the data and give a reliable statement on the significance. Moreover, temporal and spatial changes often lead to the violation of stationarity, a key assumption of many standard statistical approaches. This makes hydrological statistics interesting and challenging for so many researchers.

Geostatistics is the discipline that investigates the statistics of spatially extended variables. Spatio-temporal analysis is at the forefront of geostatistical research these days, and its impact is expected to increase in the future. This trend will be driven by increasing needs to advance risk assessment and management strategies for extreme events such as floods and droughts, and to support both short and long-term water management planning. Current trends and variability of hydrological extremes call for spatio-temporal and/or geostatistical analysis to assess, predict, and manage water related and/or interlinked hazards.

The aim of this session is to provide a platform and an opportunity to demonstrate and discuss innovative applications and methodologies of spatio-temporal analysis in a hydrological (hydrometeorological) context. The session is targeted at both hydrologists and statisticians interested in the spatial and temporal analysis of hydrological events, extremes, and related hazards, and it aims to provide a forum for researchers from a variety of fields to effectively communicate their research.
This session is co-sponsered by ICSH-STAHY (IAHS).

Geostatistics is commonly applied in the Water, Earth and Environmental sciences to quantify spatial variation, produce interpolated maps with quantified uncertainty and optimize spatial sampling designs. Extensions to the space-time domain are also a topic of current interest. Due to technological advances and abundance of new data sources from remote and proximal sensing and a multitude of environmental sensor networks, big data analysis and data fusion techniques have become a major topic of research. Furthermore, methodological advances, such as hierarchical Bayesian modeling and machine learning, have enriched the modelling approaches typically used in geostatistics.

Earth-science data have spatial and temporal features that contain important information about the underlying processes. The development and application of innovative space-time geostatistical methods helps to better understand and quantify the relationship between the magnitude and the probability of occurrence of these events.

This session aims to provide a platform for geostatisticians, soil scientists, hydrologists, earth and environmental scientists to present and discuss innovative geostatistical methods to study and solve major problems in the Water, Earth and Environmental sciences. In addition to methodological innovations, we also encourage contributions on real-world applications of state-of-the-art geostatistical methods.

Given the broad scope of this session, the topics of interest include the following non-exclusive list of subjects:
1. Advanced parametric and non-parametric spatial estimation and prediction techniques
2. Big spatial data: analysis and visualization
3. Optimisation of spatial sampling frameworks and space-time monitoring designs
4. Algorithms and applications on Earth Observation Systems
5. Data Fusion, mining and information analysis
6. Integration of geostatistics with optimization and machine learning approaches
7. Application of covariance functions and copulas in the identification of spatio-temporal relationships
8. Geostatistical characterization of uncertainties and error propagation
9. Bayesian geostatistical analysis and hierarchical modelling
10. Functional data analysis approaches to geostatistics
11. Geostatistical analysis of spatial compositional data
12. Multiple point geostatistics
13. Upscaling and downscaling techniques
14. Ontological framework for characterizing environmental processes

This session aims to bring together researchers working with big data sets generated from monitoring networks, extensive observational campaigns and detailed modeling efforts across various fields of geosciences. Topics of this session will include the identification and handling of specific problems arising from the need to analyze such large-scale data sets, together with methodological approaches towards semi or fully automated inference of relevant patterns in time and space aided by computer science-inspired techniques. Among others, this session shall address approaches from the following fields:
• Dimensionality and complexity of big data sets
• Data mining in Earth sciences
• Machine learning, deep learning and Artificial Intelligence applications in geosciences
• Visualization and visual analytics of big and high-dimensional data
• Informatics and data science
• Emerging big data paradigms, such as datacubes

This interdisciplinary session welcomes contributions on novel conceptual approaches and methods for the analysis of observational as well as model time series from all geoscientific disciplines.

Methods to be discussed include, but are not limited to:
- linear and nonlinear methods of time series analysis
- time-frequency methods
- predictive approaches
- statistical inference for nonlinear time series
- nonlinear statistical decomposition and related techniques for multivariate and spatio-temporal data
- nonlinear correlation analysis and synchronisation
- surrogate data techniques
- filtering approaches and nonlinear methods of noise reduction
- artificial intelligence and machine learning based analysis and prediction for univariate and multivariate time series

Contributions on methodological developments and applications to problems across all geoscientific disciplines are equally encouraged.

Heavy precipitation events in small and medium size catchments can trigger flash floods, which are characterized by very short response times and high specific peak discharges, and often occur in ungauged basins. Under appropriate geomorphological conditions, such rainstorms also cause debris flows or shallow landslides mobilizing large amounts of unconsolidated material. Although significant progress has been made in the management of these different hazards and related risks, they remain poorly understood and their predictability is affected by large uncertainties, due to the fast evolution of triggering rainfall events, the lack of appropriate observations, the high variabilities and non-linearities in the physical processes, and the high variability and complexity of societal vulnerability.

This session aims to illustrate current advances in monitoring, understanding, modelling, and forecasting flash floods and associated geomorphic processes, and documenting and anticipating the societal impacts and social responses.

Contributions on the following scientific themes are more specifically expected:
- Development of new measurement techniques adapted to flash floods monitoring (including remote sensing data, weather radar, and lightning), and quantification of the associated uncertainties,
- Identification of processes leading to flash flood events and/or rainfall-induced geomorphic hazards from data analysis and/or modelling, and of their characteristic space-time scales
- Possible evolutions in hazard characteristics and frequency related to climate change.
- Development of short-range (0-6h) rainfall forecasting techniques adapted to heavy precipitation events, and representation of associated uncertainties
- Development of hydro-meteorological forecasting chains for predicting flash floods and/or rainfall-induced geomorphic hazards in gauged and ungauged basins
- Development of inundation mapping approaches specifically designed for an integration in flash floods forecasting chains.
- Use of new criteria such as specific “hydrological signatures” for model and forecast evaluation
- Observation, understanding and prediction of the societal vulnerability and social responses to flash floods and/or associated hydro-geomorphic hazards.

Drought and water scarcity are important issues in many regions of the Earth. While an increase in the severity and frequency of droughts can lead to water scarcity situations, particularly in regions that are already water-stressed, overexploitation of available water resources can exacerbate the consequences of droughts. In the worst case, this can lead to long-term environmental and socio-economic impacts. It is, therefore, necessary to improve both monitoring and sub-seasonal to seasonal forecasting for droughts and water availability and to develop innovative indicators and methodologies that translate the information provided into effective drought early warning and risk management. This session addresses statistical, remote sensing and physically-based techniques, aimed at monitoring, modelling and forecasting hydro-meteorological variables relevant to drought and/or water scarcity. These include, but are not limited to, precipitation, snow cover, soil moisture, streamflow, groundwater levels, and extreme temperatures. The development and implementation of drought indicators meaningful to decision-making processes, and ways of presenting and explaining them to water managers, policymakers and other stakeholders, are further issues that are addressed. The session aims to bring together scientists, practitioners and stakeholders in the fields of hydrology and meteorology, as well as in the field of water resources and/or risk management; interested in monitoring, modelling and forecasting drought and water scarcity, and in analyzing their interrelationships, hydrological impacts, and the feedbacks with society. Particularly welcome are applications and real-world case studies in regions subject to significant water stress, where the importance of drought warning, supported through state-of-the-art monitoring and forecasting of water resources availability is likely to become more important in the future. Contributors to the session are invited to submit papers to the Special Issue (SI) entitled "Recent advances in drought and water scarcity monitoring, modelling, and forecasting", to be published in the open-access journal Natural Hazard and Earth System Sciences (https://www.natural-hazards-and-earth-system-sciences.net/special_issues/schedule.html). Submission is open until 30 July 2020, for manuscripts that are not under consideration for publication elsewhere.

Public information:
A tutorial video on "how to see and reply to comments on your display" is available for all participants at:
https://www.youtube.com/watch?v=xTCPKDmgSVw

This session brings together scientists, forecasters, practitioners and stakeholders interested in exploring the use of ensemble hydro-meteorological forecast techniques in hydrological applications: e.g., flood control and warning, reservoir operation for hydropower and water supply, transportation, and agricultural management. It will address the understanding of sources of predictability and quantification and reduction of predictive uncertainty of hydrological extremes in deterministic and ensemble hydrological forecasting. Uncertainty estimation in operational forecasting systems is becoming a more common practice. However, a significant research challenge and central interest of this session is to understand the sources of predictability and development of approaches, methods and techniques to enhance predictability (e.g. accuracy, reliability etc.) and quantify and reduce predictive uncertainty in general. Ensemble data assimilation, NWP preprocessing, multi-model approaches or hydrological postprocessing can provide important ways of improving the quality (e.g. accuracy, reliability) and increasing the value (e.g. impact, usability) of deterministic and ensemble hydrological forecasts. The models involved with the methods for predictive uncertainty, data assimilation, post-processing and decision-making may include machine learning models, ANNs, catchment models, runoff routing models, groundwater models, coupled meteorological-hydrological models as well as combinations (multimodel) of these. Demonstrations of the sources of predictability and subsequent quantification and reduction in predictive uncertainty at different scales through improved representation of model process (physics, parameterization, numerical solution, data support and calibration) and error, forcing and initial state are of special interest to the session.

The session welcomes new experiments and practical applications showing successful experiences, as well as problems and failures encountered in the use of uncertain forecasts and ensemble hydro-meteorological forecasting systems. Case studies dealing with different users, temporal and spatial scales, forecast ranges, hydrological and climatic regimes are welcome.

The session is part of the HEPEX international initiative: www.hepex.org

This interactive session aims to bridge the gap between science and practice in operational forecasting for different water-related natural hazards. Operational (early) warning systems are the result of progress and innovations in the science of forecasting. New opportunities have risen in physically based modelling, coupling meteorological and hydrological forecasts, ensemble forecasting and real time control. Often, the sharing of knowledge and experience about developments are limited to the particular field (e.g. flood forecasting or landslide warnings) for which the operational system is used.

The focus of this session will be on bringing the expertise from different fields together as well as exploring differences, similarities, problems and solutions between forecasting systems for varying natural hazards. Real-world case studies of system implementations - configured at local, regional and national scales - will be presented, including trans-boundary issues. An operational warning system can include, for example, monitoring of data, analysing data, making forecasts, giving warning signals and suggesting response measures.

Contributions are welcome from both scientists and practitioners who are involved in developing operational forecasting and/or management systems for water-related natural or man-made hazards, such as flood, drought, tsunami, landslide, hurricane, hydropower, pollution etc.

Many water management sectors are already having to cope with extreme weather events, climate variability and change. In this context, predictions on sub-seasonal, seasonal to decadal timescales (i.e. horizons ranging from months to a decade) are an emerging and essential part of hydrological forecasting. By providing science-based and user-specific information on potential impacts of extreme events, operational hydro-meteorological services are invaluable to a range of water sectors such as transport, energy, agriculture, forestry, health, insurance, tourism and infrastructure.

This session aims to cover the advances in climate and hydro-meteorological forecasting, and their implications on forecasting extreme events for improved water management. It welcomes, without being restricted to, presentations on:

- Making use of climate data for hydrological modelling (downscaling, bias correction, temporal disaggregation, spatial interpolation and other technical challenges),
- Methods to improve forecasting of hydrological extremes,
- Improved representations of hydrological extremes in a future climate,
- Seamless forecasting, including downscaling and statistical post- and pre-processing,
- Propagation of climate model uncertainty to hydrological models and impact assessment,
- Lessons learnt from forecasting and managing present day extreme conditions,
- Operational hydro-meteorological (sub-seasonal to decadal) forecasting systems and climate services,
- Effective methods to link stakeholder interests and scientific expertise (e.g. service co-generation).

The session will bring together research scientists and operational managers in the fields of hydrology, meteorology and climate, with the aim of sharing experiences and initiating discussions on this emerging topic. We encourage presentations from initiatives such as the H2020 IMPREX, BINGO, S2S4E and CLARA projects, and from WWRP/WCRP S2S projects that utilise the recently established S2S project database, and all hydrological relevant applications.

Public information:
Welcome to HS4.6 at #shareEGU20!

This session aims to cover the advances in climate and hydro-meteorological forecasting, and their implications on forecasting extreme events for improved water management. We thank the authors for their valuable contributions to this session. We have a range of brilliant displays, which cover a range of forecast lead times, case study areas and applications.

The displays for the session have been grouped into two categories: Research Studies and Operational & Applied Studies, with each display having a 5 min slot for discussion.

We will start the session at 10:45 CET on Thursday 07 May. The display times listed below may change a bit last minute, but this is the schedule we will try to stick to.

We hope you will enjoy the session!
--- HS4.6 session co-conveners


***

10:45-10:50 CET
Welcome and opening remarks

Research Studies:

10:50-10:55
D252: EGU2020-17646 - Spatial and temporal patterns in seasonal forecast skill based on river flow persistence in Irish catchments
Daire Quinn et al.

10:55-11:00
D253: EGU2020-9149 - Seasonal streamflow forecasting - Which are the drivers controlling the forecast quality?
Ilias Pechlivanidis et al.

11:00-11:05
D254: EGU2020-18796 - Sensitivity of seasonal hydrological predictability sources to catchment properties
Maria Stergiadi et al.

11:05-11:10
D255: EGU2020-1533 - Analysis and prediction of hydrological extreme conditions for a small headwater catchment in a German lower mountain range
Lisa Hennig et al.

11:10-11:15
D257: EGU2020-9321 - Sensitivity analysis of MOHID-Land model. Calibration and validation of Ulla river watershed.
Ana Oliveira et al.

11:15-11:20
D260: EGU2020-2167 - Modelling runoff generation of a small catchment in the context of climate change by using an ensemble of different climate model outputs and bias correction methods
Kai Sonntag et al.

11:20-11:30
Open discussion and short break (if time allows)

Operational & Applied Studies:

11:30-11:35
D261: EGU2020-9773 - A Real-time Ensemble Hydrological Forecasting System over Germany at Sub-seasonal to Seasonal Time Range
Husain Najafi et al.

11:35-11:40
D262: EGU2020-20290 - Towards improved disaster preparedness and climate proofing in semi-arid regions: development of an operational seasonal forecasting system
Christof Lorenz et al.

11:40-11:45
D263: EGU2020-5494 - Using seasonal forecast for energy production: SHYMAT climate service, a small hydropower management and assessment tool
Eva Contreras Arribas et al.

11:45-11:50
D264: EGU2020-5550 - How seasonal forecast can improve the water planning in multipurpose reservoirs: ROAT climate service, a reservoir operation assessment tool
Javier Herrero Lantarón et al.

11:50-11:55
D265: EGU2020-15853 - SMHI Aqua: a new co-generated hydro-climate service to enable sustainable freshwater management
Carolina Cantone et al.

11:55-12:00
D266: EGU2020-9006 - Using seasonal forecast information to strengthen resilience and improve food security in Niger River Basin
Bernard Minoungou et al.

12:00-12:15
Open discussion and HS4.6 closing remarks

Statistical post-processing techniques for weather, climate, and hydrological forecasts are powerful approaches to compensate for effects of errors in model structure or initial conditions, and to calibrate inaccurately dispersed ensembles. These techniques are now an integral part of many forecasting suites and are used in many end-user applications such as wind energy production or flood warning systems. Many of these techniques are flourishing in the statistical, meteorological, climatological, hydrological, and engineering communities. The methods range in complexity from simple bias correction up to very sophisticated distribution-adjusting techniques that take into account correlations among the prognostic variables.

At the same time, a lot of efforts are put in combining multiple forecasting sources in order to get reliable and seamless forecasts on time ranges from minutes to weeks. Such blending techniques are currently developed in many meteorological centers.

In this session, we invite papers dealing with both theoretical developments in statistical post-processing and evaluation of their performances in different practical applications oriented toward environmental predictions, papers dealing with the problem of combining or blending different types of forecasts in order to improve reliability from very short to long time scales.

The Sendai Framework for disaster risk reduction (SFDRR) and its seventh global target recognizes that increased efforts are required to develop risk-informed and impact-based multi-hazard early warning systems. Despite significant advances in disaster forecasting and warning technology, it remains challenging to produce useful forecasts and warnings that are understood and used to trigger early actions. Overcoming these challenges requires understanding of the reliability of forecast tools and implementation barriers in combination with the development of new risk-informed processes. It also requires a commitment to create and share risk and impact data and to co-produce impact-based forecasting models and services. To deal with the problem of coming into action in response to imperfect forecasts, novel science-based concepts have recently emerged. As an example, Forecast-based Financing and Impact-based Multi-Hazard Early Warning Systems are currently being implemented operationally by both governmental and non-governmental organisations in several countries as a result of increasing international effort by several organizations such as the WMO, World Bank, IFRC and UNDRR to reduce disaster losses and ensuring reaching the objectives of SFDRR. This session aims to showcase lessons learnt and best practices on impact-based multi-hazards early warning system from the perspective of both the knowledge producers and users. It presents novel methods to translate forecast of various climate-related and geohazards into an impact-based forecast. The session addresses the role of humanitarian agencies, scientists and communities at risk in creating standard operating procedures for economically feasible actions and reflects on the influence of forecast uncertainty across different time scales in decision-making. Moreover, it provides an overview of state-of-the-art methods, such as using Artificial Intelligence, big data and space applications, and presents innovative ways of addressing the difficulties in implementing forecast-based actions. We invite submissions on the development and use of operational impact-based forecast systems for early action; developing cost-efficient portfolios of early actions for climate/geo-related impact preparedness such as cash-transfer for droughts, weather-based insurance for floods; assessments on the types and costs of possible forecast-based disaster risk management actions; practical applications of impact forecasts.

Highly varying hydro-climatological conditions, multi-party decision-making contexts, and the dynamic interconnection between water and other critical infrastructures create a wealth of challenges and opportunities for water resources planning and management. For example, reservoir operators must account for a number of time-varying drivers, such as the downstream users’ demands, short- and long-term water availability, electricity prices, and the share of power supplied by wind and solar technologies. In this context, adaptive and robust management solutions are paramount to the reliability and resilience of water resources systems. To this purpose, emerging work is focusing on the development of models and algorithms that adapt short-term decisions to newly available information, often issued in the form of weather or streamflow forecasts, or extracted from observational data collected via pervasive sensor networks, remote sensing, cyberinfrastructure, or crowdsourcing.

In this session, we solicit novel contributions related to improved multi-sectoral forecasts (e.g., water availability and demand, energy and crop prices), novel data analytics and machine learning tools for processing observational data, and real-time control solutions taking advantage of this new information. Examples include: 1) approaches for incorporating additional information within control problems; 2) methods for characterizing the effect of forecast uncertainty on the decision-making process; 3) integration of information with users’ preferences, behavioral uncertainty, and institutional setting; 4) studies on the scalability and robustness of optimal control algorithms. We welcome real-world examples on the successful application of these methods into decision-making practice.

While water plays a critical role in sustaining human health, food security, energy production and ecosystem services, factors such as population growth, climate and land use change increasingly threaten water quality and quantity. The complexity of water resources systems requires methods integrating technical, economic, environmental, legal, and social issues within a framework that allows for the design and testing of efficient and sustainable water management strategies to meet the pressing global water challenges of the 21st century. Current systems analysis practice adopt a practical, problem-oriented approach for addressing the most challenging water issues of our times. It is marked by competing objectives, interdisciplinary processes, and dynamic adaptation under high levels of uncertainty. The session will feature state-of-the-art contributions on systems approaches and solutions for water management in an uncertain environment.

Public information:
The order of presentation of displays is in the table in the attached summary file

Semi-arid regions are facing the challenge of managing water resources under conditions of climate change, extreme events (flash floods, drought), increasing scarcity, and concerns about water quality. Already, the availability of fresh water in sufficient quality and quantity is one of the major factors limiting socio-economic development. Especially, in terms of hydrology semi-arid regions are characterized by very complex hydro- and hydrogeological systems that frequently exhibit extreme behavior. The complexity of the water cycle contrasts strongly with the often poor data availability, which limits the number of analysis techniques and methods available to researchers.
Discussing frameworks that provide water assessment, management, and allocation solutions for water and data scarce regions is the focus of this session. Specifically, this session emphasizes on recent advances in science as well as on practical application, including:
- The development, analysis, and application of new data collection techniques, such as environmental sensor networks, satellite imagery and participatory data collection methods, but also human capacity development.
- New understanding of hydrological processes that are characteristic for semi-arid regions, such as large scale droughts and other extremes.
- Innovative water management strategies, such as the storage of reclaimed water or excess water from different sources in Managed Aquifer Recharge (MAR).
- Methodologies for assessing the impact and cost-effectiveness of selected response measures toward an optimal water allocation.
- Best water scarcity and droughts indicators for the estimation of desertification risks across a range of scales.
- Specific targets regarding water efficiency, to allow for sustainable ecosystem services in the river basins.
- Programs of measures to deal with desertification impact on the management & planning of water resources and on the economic development.
- Studies on the social implications of different water allocation strategies.
- Type of Water-related Ecosystem Services (WES) provided for river basin management, the existing supply and demand hotpots and the extent to which trade-offs and synergies might arise.

Global and regional water management is facing major challenges to reach targeted water quality goals. Globally, major socio-economic developments are triggering a new water quality challenge, particularly in developing and transition countries. Increasing population and expanding public water supplies that fail to adequately address the treatment of wastewater flows, lead to significant water quality deterioration. Regionally, the diffuse transfer of pollutants from land to water presents a major challenge. Land modifications and changing weather patterns such as the frequency and magnitude of storms and the periodicity of droughts contribute to water quality degradation with potential risks to human and ecosystem health, food security, and the economy.
The United Nations Sustainable Development Goal 6 requires countries to monitor progress towards ‘ensuring sustainable management of water and sanitation for all' and set-up appropriate monitoring systems and indicators. SDG6 requires defining base lines, trends and targets to review the effectiveness of pollution mitigation measures. High frequency monitoring and long time series have improved our process-based understanding of pollutant losses to water at catchment level. However, the patterns in water quality due to source management could be confounded by the effect of larger climate and weather cycles. Moreover, in many data poor locations, policy and management can only be informed by the interpretation of lower resolution data.
This session focuses on global and regional water quality research and assessments concerning methods and data sets required to evaluate sustainable development measures. We invite submissions on: (i) methods to assess signals and trends in water quality, (ii) assessment of hydrological and biogeochemical processes on pollutant transfer and their relationship to climate effects, time lags and/or adaptive management changes, (iii) development of new modelling and data-driven frameworks identifying hotspots of water quality degradation posing a risk to human and ecosystem health, water and food security, and (iv) model and data based evaluations of strategies to improve water quality.

The research field of socio-hydrology emerged as an attempt to better understand the dynamic interactions and feedbacks within diverse coupled human-water systems and its implications for the assessment and management of water resources and associated risks. While acknowledging that the human impact on natural processes has reached unprecedented levels, the socio-hydrological perspective provides for a comprehensive understanding of integrated water systems and aims to identify adequate solutions for water supply, management, and adaptation to risk.
Socio-hydrology offers novel entry points for a more fertile engagement between hydrological and social sciences across different scales ranging from the plot level to entire watersheds. Its interdisciplinary nature encompasses (and integrates) various methodological approaches, epistemologies, and disciplines.
We welcome contributions from researchers from social and natural sciences who are keen to look beyond their research perspective and who like to discuss their research findings in a broader context of coupled human water systems, i.e. the subject matter of socio-hydrology. Abstracts are solicited on topics that deal with planetary water boundary concepts, integrated assessment models (IAMs), water history and archaeology, sustainability of engineered river basins, water valuation (both monetary and non-monetary), urbanizing deltas etc. with a focus on understanding feedbacks and the spatial and temporal dynamics between human society (from individuals to global levels) and their environment and/or simulating plausible co-evolutionary dynamics that emerges into the future. Resulting policy insights for a sustainable future are equally welcomed. Coupled systems can be human-flood systems, human-infrastructure systems, human-irrigation systems, human-agricultural systems, human-delta systems etc. Papers should 1) contribute to the understanding of complex human-water relations and their management, 2) discuss the benefits and shortcomings based on empirical, conceptual or model-based research and disciplinary perspective; and 3) shed light on the added value of socio-hydrological modelling for risk-based decision making and adaptation design.
This session is jointly developed with the framework of the Panta Rhei Research Initiative of the International Association of Hydrological Sciences (IAHS) under the working group of “Socio-hydrological modeling and synthesis”.

Water utilities and municipalities must embrace technological innovation to address the exacerbating challenges and uncertainty posed by climate change, urbanization, and population. The progressive digitalization of urban water infrastructure, and the adoption of IoT solutions for water resources, are opening new opportunities for the design, planning, and management of more sustainable and resilient urban water networks and systems. At the same time, the “digital water” revolution is strengthening the interconnection between urban water systems and other critical infrastructure (e.g., energy grids, transportation networks) motivating the development of novel approaches accounting for the intrinsic complexity of such coupled systems. This session aims to provide an active forum to discuss and exchange knowledge on state-of-the-art and emerging tools, framework, and methodologies for planning and management of modern urban water infrastructure, with a focus on digitalization and/or interconnection with other systems. Topics and applications could belong to any area of urban water demand and supply network analysis, modelling and management, including intelligent sensors and advanced metering, novel applications of IoT for urban water, and challenges to their implementation or risk of lock-in of rigid system designs. Additional topics may include big-data analysis and information retrieval, data-driven behavioural analysis, descriptive and predictive models of water demand, experimental approaches to demand management, water demand and supply optimization, trend and anomaly (e.g., leak) identification. Examples of interesting investigations on interconnected systems include cyber-physical security of urban water systems (i.e., communication infrastructure), combined reliability studies on power-to-water networks (energy), and minimization of impacts of urban flooding on traffic (transportation).

The notion of water security has been interpreted in a variety of ways through engineering, socioeconomic, geophysical, and integrated modeling approaches. The social disciplines emphasize on human welfare and security, while the natural sciences focus more on hydrological balance and natural hazards. In all cases, water security is perceived as a very complex concept where both hydrological and social components interacting with each other, which makes the definition of security notion challenging.

Various indicators were developed at different scales for global or national assessment and with different thematic focus, but all of them were criticized for being biased concerning certain aspects, not well-founded with data, or oversimplifying complex water-society interrelations. The suggested approaches often represent water security in a fragmented manner, while the relevant indicators cannot fully attribute security status at a country or regional level. This can result in misinterpretation of the water security situation in policy dialogues, also affecting bilateral and multilateral relations among countries.

Often, water security is perceived through the water-for-food governance framework to sustainably manage locally scarce water resources. This requires performance indicators that somehow reflect spatiotemporal variations, different interests and perspectives. Examples of such indicators include water footprints of food consumers, crop water productivities, basin-level water accounts and irrigation efficiency. Insights from agricultural water management, water resources management, socio-hydrology and other fields can be used to develop and interpret performance indicators to better inform actors in water-for-food governance, all the way from the field to the fridge.

In this session, we invite contributions of different approaches and indicators toward water security assessment and its reflection on policy making aspects. We are interested on original and review studies focusing on inter-disciplinary conceptualization of water security by including different dimensions like hydrological, socio-economic, environmental parameters among others. We also welcome studies on the interpretation of water security into risk management assessments, governance aspects, and development of early warning and forecasting systems

Water plays a critical role in sustaining agricultural production, energy generation, economic development, and ecosystem services worldwide. However, in an era of increasing water scarcity and climate change, new integrative approaches to water management and policy are required to successfully balance competing societal goals of environmental conservation, food, energy and water security. This session will provide a forum for novel and emerging research in the field of water-food-energy-environment systems that highlights: (i) improved understanding about the critical interconnections, feedbacks, and risks between system components, (ii) develops new methods or tools for evaluating and monitoring system trade-offs and performance , and (iii) evaluates integrated technical, policy, and/or governance nexus solutions to address critical water-food-energy-environment system challenges in different locations and at various scales (local, regional, and even global).

Invited speaker: Jennifer Burney (University of California San-Diego)

The transition to a low-carbon economy will require the development of innovative methods to integrate renewable sources of energy while minimizing the additional pressure on closely connected ecosystems.

Hydropower is a mature and cost-competitive renewable energy source, which helps stabilize fluctuations between energy demand and supply. Depending on the relative capacities of the intermittent renewables and hydropower facilities, integration may require changes in the way hydropower facilities operate to provide balancing, reserves or energy storage. Moreover, non-power constraints on the hydropower system, such as irrigation water deliveries, environmental constraints, recreation, flood control and variable social acceptance tend to reduce the ability of hydropower to integrate variable renewable.

This session solicits contributions that describe, characterize, or model distributed renewable energy sources at different spatial and temporal scales that are relevant for planning and management of electricity systems. Special attention will be devoted to the interactions between the energy-water system and the climate and hydrological variables that govern production in space and time. Of particular interest are case studies and other contributions of hydrology and power grid modernization initiatives to understand these complex interdependencies. The development of new modeling approaches to analyze interactions with climate-policy and power grid management options, socio-economic mitigation measures and land use are welcome.

Questions of interest include:
- How to predict water availability for hydropower production?
- How to predict and quantify the space-time dependences and the positive/negative feedbacks between wind/solar energies, water cycle and hydropower?
- How do energy, land use and water supply interact during transitions?
- What policy requirements or climate strategies are needed to manage and mitigate risks in the transition?
- Quantification of energy production impacts on ecosystems such as hydropeaking effects on natural flow regimes.

This session has the support of the European Energy Research Alliance (EERA) that established the joint program “Hydropower” to facilitate research, promote hydropower and enable sustainable electricity production. Further information can be found here:
https://www.eera-set.eu/eera-joint-programmes-jps/list-of-jps/hydropower/

Evapotranspiration (ET) is the key water flux at the interface of soil, vegetation and atmosphere. ET is difficult to measure directly; therefore, a range of methods have been developed within different research disciplines to estimate ET.

Remote sensing datasets are increasingly being used to provide spatially-explicit, large-scale ET estimates. While satellite datasets have been used to estimate basin- to field-scale ET, aerial platforms such as UAVs and drones are becoming popular for field-scale studies. These datasets, in combination with micrometeorological data, can be used to produce empirical models for improving ET estimates at larger scales. However, the uncertainty in ET that varies by the datasets which are used, hydro-climatic region, spatiotemporal scale, and modelling approaches, is not well understood.

Additionally, there is a range of in-situ methods such as lysimeters, sap flow, eddy covariance, scintillometers and Bowen ratio to estimate ET from ground-based measurements. However, estimating and scaling in-situ ET is prone to large method-specific uncertainties which are rarely communicated across different disciplines. This is problematic if in-situ measurements are to be compared, combined or scaled up to match the grid resolution of remote sensing products or models.

This session addresses ET estimation with both remote sensing and in-situ methods. We invite contributions that (1) assess and compare established and new in-situ and remote sensing ET estimates, (2) address uncertainty in these methods, (3) bridge spatio-temporal scales in different ET estimates (4) incorporate remote sensing and in-situ measurements into process-based modelling approaches.

Land-atmospheric interaction includes the land surface and atmospheric states and the mass and energy exchanges between land surface and the atmosphere. It is a key part of the Earth's weather and climate system. Studies of the land-atmosphere interaction are critical to the understanding of the Earth’s weather and climate system that is required for accurate weather and climate forecasts. These studies mainly involve ground observations, air-borne or space based remote sensing of land surface and the lower atmosphere properties, mass and energy fluxes and their dynamics, and numerical model simulations of the land-atmosphere processes. Since the 1970s, a large number of field observation experiments (such as FIFE, HAPEX/Sahel, HAPEX/MOBILHY, EFEDA, BOREAS, NOPEX, GAME, HEIFE, TIPEX, EAGLE, CAMP/Tibet, TPE and LOPEXs) have been or are currently being carried out over a wide range of different underlying land surfaces worldwide. Dozens of land process parameterization schemes or land surface models have been developed and refined. Major national and international agencies (e.g. NASA, NOAA, ESA, EUMETSAT, JAXA, CMA, JMA, KMA, etc.) have launched many satellite missions to provide continuous spatially distributed observations of land surface and atmospheric observations from local scale to regional and even global scales. Examples of these missions are EOS, Meteosat, EPS, GCOM-W, GOES, S-NPP, JPSS, FYs, SMOS, SMAP, etc. Assimilation of these observations have significantly improved understanding of the land-atmosphere interaction and in turn gradually enhanced the prediction skills of the simulation models at all of these scales. This session invites abstracts that report the development, validation and applications of these studies especially in the Third Pole Environment regions in the recent years. New development on land surface process observation, data fusion, data assimilation, hydrological hazards monitoring, climate and environmental changes at regional and global scales are especially encouraged.

Public information:
Welcome to " HS6.2/AS2.5:Ground and Remote Sensing Observations and Modeling for Land-Atmospheric Interactions" session

We invite presentations concerning soil moisture estimation, including remote sensing, field experiments, land surface modelling and data assimilation. The technique of microwave remote sensing has made much progress toward its high potential to retrieve surface soil moisture at different scales. From local to landscape scales several field or aircraft experiments (e.g. SMAPvex) have been organised to improve our understanding of active and passive microwave soil moisture sensing, including the effects of soil roughness, vegetation, spatial heterogeneities, and topography. At continental scales a series of several passive and active microwave space sensors, including SMMR (1978-1987), AMSR (2002-), ERS/SCAT (1992-2000) provided information on surface soil moisture. Current investigations in L-band passive microwave with SMOS (2009-) and SMAP (2015-), and in active microwave with Metop/Ascat series (2006-) and Sentinel-1 open new possibilities in the quantification of the soil moisture at regional and global scales. Comparison between soil moisture simulated by land surface models, in situ observations, and remotely sensed soil moisture is also relevant to characterise regional and continental scale soil moisture dynamics (e.g., ALMIP2, GSWP3).



We encourage submissions related to soil moisture remote sensing, including:
- Field experiment, theoretical advances in microwave modelling and calibration/validation activities.
- High spatial resolution soil moisture estimation based on Sentinel-1 observations, GNSS reflections, or using novel downscaling methods. 

- Inter-comparison and inter-validation between land surface models, remote sensing approaches and in-situ validation networks.
- Evaluation and trend analysis of soil moisture data record products such as the soil moisture CCI product or soil moisture re-analysis products (e.g. MERRA-Land, ERA-Land).
- Root zone soil moisture retrieval and soil moisture assimilation in land surface models as well as in Numerical Weather Prediction models.
- Application of satellite soil moisture products for improving hydrological applications such as flood prediction, drought monitoring, rainfall estimation.

Remote sensing techniques are widely used to monitor the relationship between the water cycle and vegetation dynamics and its impact on the carbon and energy cycles. Measurements of vegetation water content, transpiration and water stress contribute to a better global understanding of the water movement in the soil-plant system. This is critical for the detection and monitoring of droughts and their impact on biomass, productivity and feedback on water, carbon and energy cycles. With the number of applications and (planned) missions increasing, this session aims to bring researchers together to discuss the current state and novel findings in the remote observation of the interactions between vegetation and hydrology. We aim to (1) discuss novel research and findings, (2) exchange views on what should be done to push the field forward, and (3) identify current major challenges.

We encourage authors to submit presentations on:
• Remote sensing data analyses,
• Modelling studies,
• New hypothesis,
• Enlightening opinions.

Public information:
Dear colleagues,

The chat session on Remote sensing of interactions between vegetation and hydrology​ will be organized according to four topics:
Monitoring of vegetation and hydrology interactions with radar
Phenology dynamics and its relation to hydrological variables
Impact of land cover on vegetation and hydrology
The use and development of indices for monitoring vegetation and water stress

More information on the presenters and moderators per topic can be found in the session materials.
We hope to meet you all in the online chat!

Best Regards,
Tim, Julia, Brianna, Virginia and Mariette

The socio-economic impacts associated with floods are increasing. According to the International Disaster Database (EM-DAT), floods represent the most frequent and most impacting, in terms of the number of people affected, among the weather-related disasters: nearly 0.8 billion people were affected by inundations in the last decade (2006–2015), while the overall economic damage is estimated to be more than $300 billion. Despite this evidence, and the awareness of the environmental role of rivers and their inundation, our knowledge and accurate prediction of flood dynamics remain poor, mainly related to the lack of measurements and ancillary data at the global level.

In this context, remote sensing represents a value source of data and observations that may alleviate the decline in field surveys and gauging stations, especially in remote areas and developing countries. The implementation of remotely-sensed variables (such as digital elevation model, river width, flood extent, water level, land cover, etc.) in hydraulic modelling promises to considerably improve our process understanding and prediction. During the last decades, an increasing amount of research has been undertaken to better exploit the potential of current and future satellite observations, from both government-funded and commercial missions. In particular, in recent years, the scientific community has shown how remotely sensed variables have the potential to play a key role in the calibration and validation of hydraulic models, as well as provide a breakthrough in real-time flood monitoring applications. With the proliferation of open data and more Earth observation data than ever before, this progress is expected to increase.

We encourage presentations related to flood monitoring and mapping through remotely sensed data including: - Remote sensing data for flood hazard and risk mapping, including commercial satellite missions;

- Remote sensing techniques to monitor flood dynamics;
- The use of remotely sensed data for the calibration, or validation, of hydrological or hydraulic models;
- Data assimilation of remotely sensed data into hydrological and hydraulic models;
- Improvement of river discretization and monitoring based on Earth observations;
- River flow estimation from remote sensing;
- River and flood dynamics estimation from satellite (especially time lag, flow velocity, etc.)

This session concerns measurements and estimations of water levels, water extent, water storage and water discharge of surface water bodies such as rivers, lakes, floodplains and wetlands, through combined use of remote sensing and in situ measurements. Contributions that also cover aspects on assimilation of remote sensing together with in situ data within hydrodynamic models are welcome and encouraged.

The monitoring of river water levels, river discharges, water bodies extent, storage in lakes and reservoirs, and floodplain dynamics plays a key role in assessing water resources, understanding surface water dynamics, characterizing and mitigating water related risks and enabling integrated management of water resources and aquatic ecosystems.

While in situ measurement networks play a central role in the monitoring effort, remote sensing techniques is contributing in an increasing way, as they provide near real time measurements as well as long homogeneous time series to study the impact of climate change, over various scales from local to regional and global.

During the past twenty-nine years a large number of satellites and sensors has been developed and launched allowing to quantify and monitor the extent of open water bodies (passive and active microwave, optical), the water levels (radar and laser altimetry), the global water storage and its changes (variable gravity). River discharge, a key variable of hydrological dynamics, can be estimated by combining space/in situ observations and modelling, although still challenging with available space borne techniques.

Traditional instruments contribute to long-term water level monitoring and provide baseline databases. Scientific applications of more complex technologies like the SAR altimetry on CryoSat-2 and Sentinel-3A/B missions are maturing. The future SWOT mission, to be launched in 2021, will open up many new hydrology-related opportunities.

Agriculture is the largest consumer of water worldwide and at the same time irrigation is one of the sectors where there is one of the hugest differences between modern technology and the largely diffused ancient traditional practices. Improving water use efficiency in agriculture is an immediate requirement of human society for sustaining the global food security, to preserve quality and quantity of water resources and to reduce causes of poverties, migrations and conflicts among states, which depend on trans-boundary river basins. Climate changes and increasing human pressure together with traditional wasteful irrigation practices are enhancing the conflictual problems in water use also in countries traditionally rich in water. Saving irrigation water improving irrigation efficiency on large areas with modern technics is one of the first urgent action to do. It is well known in fact that agriculture uses large volumes of water with low irrigation efficiency, accounting in Europe for around 24% of the total water use, with peak of 80% in the Southern Mediterranean part and may reach the same percentage in Mediterranean non-EU countries (EEA, 2009; Zucaro 2014). North Africa region has the lowest per-capita freshwater resource availability among all Regions of the world (FAO, 2018).
Several recent researches are done on the optimization of irrigation water management to achieve precision farming using remote sensing information and ground data combined with water balance modelling.
In this session, we will focus on: the use of remote sensing data to estimate irrigation volumes and timing; management of irrigation using hydrological modeling combined with satellite data; improving irrigation water use efficiency based on remote sensing vegetation indices, hydrological modeling, satellite soil moisture or land surface temperature data; precision farming with high resolution satellite data or drones; farm and irrigation district irrigation management; improving the performance of irrigation schemes; irrigation water needs estimates from ground and satellite data; ICT tools for real-time irrigation management with remote sensing and ground data coupled with hydrological modelling.

Accurate measurements of various hydrological cycle components (e.g. precipitation, evapotranspiration, soil moisture and water storage changes) are essential for understanding the hydrological processes and further for sustainable water resources management. Hydrological cycle components are characterized by significant variability in time and space. The conventional in-situ measurements from gauges are generally considered to be the most accurate measurements, but scientific communities are often encountered with the limited availability and capability of in-situ measurements. Specifically, the network of gauge stations is often sparse and overall the number of stations is still on decreasing trend over the globe. The point-based feature makes gauge measurements insufficient to capture spatial and temporal variability of hydrological cycle components. Therefore, alternative data sources should be investigated to fill the data gaps.

Satellite remote sensing has been shown great capability of estimating various hydrological cycle components at different temporal and spatial scales. Various communities have recognized the importance of satellite remote sensing, but they have been stressing the need for improvements in accuracy and particularly the spatial resolution because the spatial resolution of remotely sensed products is still often too coarse for many applications. To this regard, a specific topic “spatial downscaling” has emerged; over last decades, considerable efforts have been made to develop various spatial downscaling algorithms to improve the spatial resolution of remotely sensed estimates.

Machine learning and geostatistical methods have been innovatively utilized to advance the spatial downscaling in satellite remote sensing community. Together with the algorithms development in spatial downscaling, further pertinent research question arise: how to accurately evaluate the skill of downscaled remote sensing products? All current approaches for evaluation contain known limitations and, hence, there is a clear need for the development of novel procedures for fair evaluation particularly considering the limitations (e.g. representativeness and availability) of ground measurements form gauge stations.

The aim of this session is to present and discuss novel procedures in spatial downscaling of remotely sensed hydrological cycle components with emphasis on algorithms development, innovative evaluation and application of downscaled estimates.

Satellite altimetry provides the possibility to observe key parts of the hydrosphere, namely the ocean, ice, and continental surface water from space. Since the launch of Topex/Poseidon in 1992 the applications of altimetry have expanded from the open oceans to coastal zones, inland water, land and sea ice. Today, seven missions are in orbit, providing dense and near-global observations of surface elevation and several other parameters. Satellite altimetry has become an integral part of the global observation of the Earth‘s system and changes therein.

In recent years, new satellite altimetry missions have been launched carrying new instruments and operating in new orbits; the CryoSat-2/Sentinel-3 missions equipped with a Delay/Doppler altimeter, the Saral AltiKa mission carrying the first Ka band altimeter, and the recently launched photon counting laser altimeter on-board NASAs ICESat-2.

Fully exploiting this unprecedented availability of observables will enable new applications and results but also require novel and adapted methods of data analysis.
Across the different applications for satellite altimetry, the data analysis and underlying methods are similar and a knowledge exchange between the disciplines will be fruitful.
In this multidisciplinary altimetry session, we therefore invite contributions which discuss new methodology and applications for satellite altimetry in the fields of geodesy, hydrology, cryosphere, oceanography, and climatology.
Topics of such studies could for example be (but not limited to): creation of robust and consistent time series across sensors, validation experiments, combination of radar and laser altimetry e. g. for remote sensing of snow, classification of waveforms, application of data in a geodetic orbit, retracking, or combination with other remote sensing data sets.

A remote sensing signal acquired by a sensor system results from electromagnetic radiation (EM) interactions from incoming or emitted EM with atmospheric constituents, vegetation structures and pigments, soil surfaces or water bodies. Vegetation, soil and water bodies are functional interfaces between terrestrial ecosystems and the atmosphere. The physical types of EM used in RS has increased during the years of remote sensing development. Originally, the main focus was on optical remote sensing. Now, thermal, microwave, polarimetric, angular and quite recently also fluorescence have been added to the EM regions under study.
This has led to the definition of an increasing number of bio-geophysical variables in RS. Products include canopy structural variables (e.g. biomass, leaf area index, fAPAR, leaf area density) as well as ecosystem mass flux exchanges dominated by carbon and water exchange. Many other variables are considered as well, like chlorophyll fluorescence, soil moisture content and evapotranspiration. New modelling approaches including models with fully coupled atmosphere, vegetation and soil matrices led to improved interpretations of the spectral and spatio-temporal variability of RS signals including those of atmospheric aerosols and water vapour.
This session solicits for papers presenting methodologies and results leading to the assimilation in biogeoscience and atmospheric models of cited RS variables as well as data measured in situ for RS validation purposes. Contributions should preferably focus on topics related to climate change, food production (and hence food security), nature preservation and hence biodiversity, epidemiology, and atmospheric chemistry and pollution (stratospheric and troposphere ozone, nitrogen oxides, VOC’s, etc). It goes without saying that we also welcome papers focusing on the assimilation of remote sensing and in situ measurements in bio-geophysical and atmospheric models, as well as the RS extraction techniques themselves.
This session aims to bring together scientists developing remote sensing techniques, products and models leading to strategies with a higher (bio-geophysical) impact on the stability and sustainability of the Earth’s ecosystems.

The hydrological response to precipitation at the catchment scale is the result of the interplay between the space-time variability of precipitation, the catchment geomorphological / pedological / ecological characteristics and antecedent hydrological conditions. Therefore, (1) accurate measurement and prediction of the spatial and temporal distribution of precipitation over a catchment and (2) the efficient and appropriate description of the catchment properties are important issues in hydrology. This session focuses on the following aspects of the space-time variability of precipitation:
- Novel techniques for measuring liquid and solid precipitation at hydrologically relevant space and time scales, from in situ measurements to remote sensing techniques, and from ground-based devices to spaceborne platforms.
- Novel approaches to better identify, understand and simulate the dominant microphysical processes at work in liquid and solid precipitation.
- Applications of measured and/or modelled precipitation fields in catchment hydrological models for the purpose of process understanding or predicting hydrological response.

The assessment of precipitation variability and uncertainty is crucial in a variety of applications, such as flood risk forecasting, water resource assessments, evaluation of the hydrological impacts of climate change, determination of design floods, and hydrological modelling in general. Within this framework, this session aims to gather contributions on research, advanced applications, and future needs in the understanding and modelling of precipitation variability, and its sources of uncertainty.
Specifically, contributions focusing on one or more of the following issues are particularly welcome:
- Novel studies aimed at the assessment and representation of different sources of uncertainty versus natural variability of precipitation.
- Methods to account for different accuracy in precipitation time series, e.g. due to change and improvement of observation networks.
- Uncertainty and variability in spatially and temporally heterogeneous multi-source precipitation products.
- Estimation of precipitation variability and uncertainty at ungauged sites.
- Precipitation data assimilation.
- Process conceptualization and modelling approaches at different spatial and temporal scales, including model parameter identification and calibration, and sensitivity analyses to parameterization and scales of process representation.
- Modelling approaches based on ensemble simulations and methods for synthetic representation of precipitation variability and uncertainty.
- Scaling and scale invariance properties of precipitation fields in space and/or in time.
- Physically and statistically based approaches to downscale information from meteorological and climate models to spatial and temporal scales useful for hydrological modelling and applications.

Hydroclimatic conditions and the availability of water resources in space and time constitute important factors for maintaining an adequate food supply, the quality of the environment, and the welfare of inhabitants, in the context of sustainable growth and economic development. This session is designed to explore the impacts of hydroclimatic variability, climate change, and the temporal and spatial availability of water resources on: food production, population health, the quality of the environment, and the welfare of local ecosystems. We particularly welcome submissions on the following topics:

Complex inter-linkages between hydroclimatic conditions, food production, and population health, including: extreme weather events, surface and subsurface water resources, surface temperatures, and their impacts on food security, livelihoods, and water- and food-borne illnesses in urban and rural environments.

Quantitative assessment of surface-water and groundwater resources, and their contribution to agricultural system and ecosystem statuses.

Spatiotemporal modeling of the availability of water resources, flooding, droughts, and climate change, in the context of water quality and usage for food production, agricultural irrigation, and health impacts over a wide range of spatiotemporal scales

Intelligent infrastructure for water usage, irrigation, environmental and ecological health monitoring, such as development of advanced sensors, remote sensing, data collection, and associated modeling approaches.

Modelling tools for organizing integrated solutions for water, precision agriculture, ecosystem health monitoring, and characterization of environmental conditions.

Water re-allocation and treatment for agricultural, environmental, and health related purposes.

Impact assessment of water-related natural disasters, and anthropogenic forcings (e.g. inappropriate agricultural practices, and land usage) on the natural environment; e.g. health impacts from water and air, fragmentation of habitats, etc.

Hydroclimatic variability is an emerging challenge with increasing implications on water resources management, planning, and the mitigation of water-related natural hazards. This variability, along with the continuous development of water demands, and aging water supply system infrastructure make the sustainability of water use a high priority for modern society. In fact, the Global Risk 2015 Report of the World Economic Forum highlights global water crises as being the biggest threat facing the planet over the next decade.

To mitigate the above concerns we need to shed light on hydroclimatic variability and change. Several questions and mysteries are still unresolved regarding natural fluctuations of climate, anthropogenic climate change and associated variability, and changes in water resources. What is a hydroclimatic trend? What is a (long term) cycle? How can we distinguish between a trend and a cycle? Is such discrimination technically useful? How do human activities affect rainfall, hydrological change and water resources availability? How to set priorities and take action to ensure sustainability in light of variability and change?

The objective of this session is to explore hydrological and climatic temporal variability and their connections and feedbacks. More specifically, the session aims to:

1. investigate the hydrological cycle and climatic variability and change, both at regional and global scales;

2. explore the interplay between change and variability and its effect on sustainability of water uses;

3. advance our understanding of the hydrological cycle, benefiting from hydrological records and innovative techniques; and

4. improve the efficiency, simplicity, and accurate characterization of data-driven modeling techniques to quantify the impacts of past, present and future hydroclimatic change on human societies.

This session is sponsored by the International Association of Hydrological Sciences (IAHS) and the World Meteorological Organization – Commission for Hydrology (WMO CHy) and it is also related to the scientific decade 2013–2022 of IAHS, entitled “Panta Rhei - Everything Flows”.

Extreme hydro-meteorological events drive a number of hydrologic and geomorphic hazards, (such as floods, landslides and debris flows) which pose a significant threat to modern societies on a global scale. The continuous increase of population and urban settlements in hazard-prone areas in combination with evidence of changes in extreme weather events lead to a continuous increase of the risk associated with weather-induced hazards. To improve resilience and to design more effective mitigation strategies, we need to better understand the aspects of vulnerability, risk, and triggers that are associated with these hazards.

This session aims to gather contributions dealing with various hydro-meteorological hazards that address the aspects of vulnerability analysis, risk estimation, impact assessment, mitigation policies and communication strategies. Specifically, we aim to collect contributions from the academia, the industry (e.g. insurance) and government agencies (e.g. civil protection) that will help identify the latest developments and ways forward for increasing the resilience of communities at local, regional and national scales, and proposals for improving the interaction between different entities and sciences.

Contributions focusing on, but not limited to, novel developments and findings on the following topics are particularly encouraged:

- Physical and social vulnerability analysis and impact assessment of precipitation-related hazards.
- Advances in the estimation of socioeconomic risk from precipitation-induced hazards.
- Characteristics of hydro-meteorological patterns leading to high-impact events.
- Evidence on the relationship between hydro-meteorological patterns and socio-economic impacts.
- Hazard mitigation procedures.
- Communication strategies for increasing public awareness, preparedness, and self-protective response.
- Impact-based forecast and warning systems.

Keywords: vulnerability analysis, risk estimation, impact assessment, mitigation strategies, precipitation induced hazards, pluvial floods.

This PICO session addresses three sub-topics :

Precipitation variability: from drop scale to lot scale:
The understanding of small scale (sec – drop scale to min -km) spatio-temporal variability of precipitation is essential for larger scale studies, especially in highly heterogeneous areas (mountains, cities). Nevertheless grasping this variability remains an open challenge. An illustration of the range of scales involved is the ratio between the effective sampling areas of point measurement devices (rain gauges and disdrometers) and weather radars, which is greater than 10^7! This session aims at bridging this scale gap and improving the understanding of small scale precipitation variability, both liquid and solid, as well as its hydro-meteorological consequences at larger scales.

Hydroclimatic and hydrometeorologic stochastics: Extremes, scales, probabilities:
The departure of statistical properties of hydrometeorological processes from the classical statistical prototype has been established. This session aims at presenting the latest developments on:
- Coupling stochastic approaches with deterministic hydrometeorological predictions;
- Stochastic-dynamic approaches;
- Variability at climatic scales and its interplay with the ergodicity of space-time probabilities;
- Linking underlying physics and scaling stochastics of hydrometeorological extremes;
- Development of parsimonious representations of probability distributions of hydrometeorological extremes over a wide range of scales and states; as well as their applications in risk analysis and hazard predictions
The session is co-sponsored by the ICSH-IAHS, former STAHY.

The atmospheric water cycle under change: feedbacks, land use, hydrological changes and implications :
Traditionally, hydrologists have always considered precipitation and temperature as input to their models and evaporation as a loss. However, more than half of the evaporation globally comes back as precipitation on land. Anthropogenic pressure through land-use changes (and greenhouse gasses) alter, not only, the local hydrology, but through atmospheric water and energy feedbacks also effect the water cycle in remote locations. This session aims to:
- investigate the remote and local atmospheric feedbacks from human interventions, based on observations and coupled modelling approaches.
- explore the implications of atmospheric feedbacks on the hydrologic cycle for land and water management (ex. changing land cover)

Urban hydrological processes are characterized by high spatial variability and short response times resulting from a high degree of imperviousness. Therefore, urban catchments are especially sensitive to space-time variability of precipitation at small scales. High-resolution precipitation measurements in cities are crucial to properly describe and analyses urban hydrological response. At the same time, urban landscapes pose specific challenges to obtaining representative precipitation and hydrological observations.

This session focuses on high-resolution precipitation and hydrological measurements in cities and on approaches to improve modeling of urban hydrological response, including:

- Novel techniques for high-resolution precipitation measurement in cities and for multi-sensor data merging to improve the representation of urban precipitation fields.
- Novel approaches to hydrological field measurements in cities, including data obtained from citizen observatories.
- Precipitation modeling for urban applications, including convective permitting models and stochastic rainfall generators.
- Novel approaches to modeling urban catchment properties and hydrological response, from physics-based, conceptual and data-driven models to stochastic and statistical conceptualization.
- Applications of measured precipitation fields to urban hydrological models to improve hydrological prediction at different time horizons to ultimately enable improved management of urban drainage systems (including catchment strategy development, flood forecasting and management, real-time control and proactive protection strategies aimed at preventing flooding and pollution).
- Strategies to deal with upcoming challenges, including climate change and rapid urbanization.

Hydro-meteorological extremes such as floods, droughts, storms, or heatwaves often affect large regions therefore causing large damages and costs. Hazard and risk assessments, aiming at reducing the negative consequences of such extreme events, are often performed with a focus on one location despite the spatial nature of extreme events. While spatial extremes receive a lot of attention by the media, little is known about their driving factors and it remains challenging to assess their risk by modelling approaches. Key challenges in advancing our understanding of spatial extremes and in developing new modeling approaches include the definition of multivariate events, the quantification of spatial dependence, the dealing with large dimensions, the introduction of flexible dependence structures, the estimation of their probability of occurrence, the identification of potential drivers for spatial dependence, and linking different spatial scales. This session invites contributions which help to better understand processes governing spatial extremes and/or propose new ways of describing and modeling spatial extremes at different spatial scales.

Target audience: hydrologists, climatologists, statisticians, machine learners, and researchers interested in spatial risk assessments.

Development and application of decision support systems to aquifers and underground reservoirs requires reliable and physically based methods to infer key parameters controlling multiphase flow and contaminant fluxes of conservative or reactive substances in the subsurface. Underground environments are complex and extremely heterogeneous exhibiting variations on a multiplicity of scales. Addressing heterogeneity in all its manifestations is the focus of exciting and intense forefront research and industrial activities.
This session (i) invites presentations on recent developments in understanding, measuring, and modelling subsurface flow and solute transport processes in both the saturated and unsaturated zones, as well as across boundaries; (ii) is aimed at providing an opportunity for specialists to exchange information and to introduce various existing and novel alternative deterministic and stochastic models of subsurface flow and transport to the general hydrological community, with critical and timely applications to environmental and industrially relevant settings.
Focus is placed on recent key developments in novel theoretical aspects and associated computational tools, fate of new contaminants, and field/laboratory applications dealing with accurate and efficient prediction and quantification of uncertainty for flow, conservative and reactive transport processes in the subsurface, in the presence of multiple information at different scales, ranging from the pore level to the intermediate and basin scales.

This session is also organized to honor Ghislain de Marsily. Prof. Ghislain de Marsily will provide a solicited presentation on "Historical perspectives on the development of stochastic methods in groundwater modelling”.

This session presents recent developments in understanding, measuring, and modelling (sub)surface hydrology and solute/vapor transport processes in both, the saturated (groundwater) and unsaturated (vadose) zone, as well as across boundaries. It is well recognized that subsurface flow is an important hydrological process transporting water, nutrients and pollutants from terrestrial to the aquatic ecosystems. Quantifying such transport processes correctly is challenging since they occur at different spatio-temporal scales. Dispersion, mixing and chemical reactions are local phenomena that strongly depend on the interplay between large-scale system heterogeneity and smaller-scale processes. These processes are of practical relevance to identify the fate of contaminants in surface and subsurface water that can affect human health and the environment. In this line, subsurface runoff is the process transporting nutrients and pollutants to the aquatic ecosystems.

The aim of this session is to discuss the effect of medium and flow heterogeneity on pore up to catchment scales. We invite contributions on laboratory and field experiments, modeling, theory as well as applications. Themes include but are not limited to the applicability of macrodispersivity, mixing and reaction under spatially variable flow, the role of diffusive processes in modeling transport in porous media, transport upscaling from pore to field-scale, the relation between advection-dispersion models and dynamic structures of catchment hydrology like travel time distributions, new characterization methods of subsurface processes, advances in transport measurement and characterization techniques.