On the linkage between humans, precipitation patterns, and floods

The growing frequency of extreme hydrologic events over multi-decadal timescales is becoming increasingly apparent at the global scale. In addition, the synchronous increase of population in flood prone areas intensifies further the impacts associated with these extreme flood events with significant societal, environmental and ecological consequences. A correct management of the impacts of extreme flood and storm events requires a greater understanding of the processes that drive them. A great challenge in such understanding is to discern whether shifts in processes, such as shifts in streamflows, also bears the signature of human activity, and if such signature is coincident (or not) with major shifts in rainfall patterns. This talk will provide an overview about this complex set of interactions, and will showcase some study cases where human drivers, rainfall patterns and floods have been analysed.

Effective management of water in the environment is a growing global imperative.
Expanding human populations, land use change and an apparent increase in the frequency and magnitude of extreme weather events, bring an added urgency to the need for effective measurement of discharge in the world’s rivers.
To effectively manage water resource availability and flood risk, while maintaining a water environment beneficial to ecology, requires accurate, reliable and timely river flow measurements. Increasingly, these measurements must also be delivered against a backdrop of diminishing resources, both human and financial.
The need therefore is for safe, resilient and cost-effective methods for the accurate and timely quantification of the discharge rate of the world’s rivers. These methods must provide consistency of results over time, through resilience to the impacts of major floods and other physical change factors, while retaining the sensitivity to allow accurate assessment of even the lowest of flows. To ensure the continued validity of long term records, new methods must be demonstrated to introduce no systematic bias to results.
This session focuses on innovative methods for measuring river discharge, and welcomes contributions with an emphasis on measuring the extremes, and dealing with difficult sites and conditions. Contributions are also invited which describe methods for effectively quantifying uncertainties associated with river discharge determinations.

The advancement of hydrological research relies on innovative methods to determine states and fluxes at high a spatiotemporal resolution. 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 noninvasive techniques allow continuous contactless and integrative measurements of hydrological state variables and fluxes from the field to basin scale (e.g. cosmic-ray neutron probes, GNSS reflectometry, ground-based microwave radiometry, gamma-ray monitoring, terrestrial gravimetry, “MacGyver” field solutions).
In this session, we encourage submissions dealing with such new types of sensing methods, ranging from instrumental aspects, improved algorithms of signal conversion, data analysis to applications of the new methods for investigating hydrological processes, and the integration of noninvasive monitored data into models from the field to the catchment scale.
In addition, we invite presentation on new data storage or transmission solutions sending data from the field (e.g. LoRa, WIFI, GSM) or started initiatives (e.g., Open-Sensing.org) that facilitate the creation and sharing of novel sensors, data acquisition and transmission systems.

This session is co-organized by the MOXXI: Observations in the 21st century working group of the IAHS.

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 climate and water. We welcome contributions about advancements on field measurement approaches, development of new sensing techniques, low cost sensor systems and whole environmental sensor networks, including remote observation techniques.
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. This session is open for all works about an existing system, planning a completely new network, upgrading an existing system, improving streaming data management, and archiving data.

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Invited Speaker is Christian Hauck (University of Fribourg) with the title:
'Geophysical monitoring techniques to observe Alpine permafrost degradation – a 20-years perspective'
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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.

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. Equally, appropriate science communication, where information is neither too complex nor infantilized, is key to open pathways to a more active and meaningful engagement.

The session will provide the opportunity for discussing with policy makers and addressing the necessary skills to facilitate the uptake of science in policy formulation and implementation: for instance, 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. It is also a platform for sharing tips and strategies to communicate scientific results and turn science into action.

Invited talk:
- "Flood management in a changing world: interactions between science and policy making", by Prof. Dr. Günter Bloeschl (Centre for Water Resource Systems, Vienna University of Technology)

This session welcomes abstracts that consider how to observe, model and analyse interactions of people 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.

When hydrology became recognized and established as a science is debatable. Sure is that there exists a long tradition of theories on the natural occurrence, distribution, and circulation of water on, in, and over the surface of the Earth (Horton, 1931). As a hydrological community we are keen to further our science, which is evident from the growing number of sub-disciplines. It is therefore of utmost importance to understand what the roots of our science are, i.e. there is a need to develop a culture of historical hydrological literacy. While further developing its terminology, concepts and methods, teaching and research can benefit from considering the relevant collective scientific knowledge base. Moreover, a historical perspective in our science avoids a ‘contemporary bias’ of ideas and theories. Science is performed and influenced by humans, hence it is never free of value, personal interest or societal pressures. The historical context in which scientists work can therefore help to understand the development of the science, its current state and future directions.
With this session we aim to stimulate the discussion on how we, as a community, develop a historical literacy and integrate this in teaching and research to enhance our science. We solicit contributions that discuss how hydrological concepts have gradually evolved over time; how forgotten methods might have contemporary value; the value of historical datasets of experimental catchments and their management; remarkable contributions of scientists, institutes and organisations.

Keith Beven, Lancaster University, will provide a solicited presentation on: 'A history of dealing with preferential flow in hydrology (or not)'

Hydrology relies strongly on heterogeneous data sets and a multitude of computational models. However, several challenges remain in order to obtain all information from the data and model results and, at the same time, carry out scientific work that is reproducible and repeatable.

Data collection is generally the first step in the scientific process, but collecting spatially and temporally dense data sets can be challenging, especially in extreme environments, such as dry, humid or cold areas. Therefore, environmental data sets are often sparse and do not allow us to fully understand the hydrological and associated environmental processes dominant in these areas. Therefore, innovative ideas are needed to build methods able to extract information from the available data and make use of the many signatures in the observations that are still to be explored.

On the other hand, an increasing amount of heterogenous data becomes available from diverse sources such as remote sensing, social media or citizen science. Platforms and tools are needed to interpret such data, identify and understand patterns, trends, and uncertainty and to draw conclusions and implications from data-driven research. New methods for data visualization can be a pivotal for our ability to make new sense of heterogeneous data and to communicate complex datasets and findings in an appropriate way to other researchers and the public.

Eventually, the full scientific process should be open, reproducible and repeatable. Many data sets contain a wide range of derived variables that cannot be easily re-computed from the raw data, either because the raw data is not available or because the computational steps are not adequately described. As a result, very few published results in hydrology are reproducible for the general reader. However, more and more software tools and platforms are becoming available to support open science, partly as a result of collaborations between software experts and hydrologists.

This session invites contributions on topics ranging from data collection and visualization to sharing model code and reproducible workflows, e.g.:

- Platforms and tools for improved data visualization, open science, scientific collaboration and/or communication with a larger audience
- Use of innovative data and data collection techniques, with a focus on data sparse environments
- Case studies illustrating challenges and solutions related to open science
- Innovative types of data and their visualizations

This session is organized in cooperation with the Young Hydrologic Society (youngHS.com).

Data assimilation is becoming more important as a method to make predictions of Earth system states. Increasingly, coupled models for different compartments of the Earth system are used. This allows for making advantage of varieties of observations, in particular remotely sensed data, in different compartments. This session focuses on weakly and strongly coupled assimilation of in situ and remotely sensed measurement data across compartments of the Earth system. Examples are data assimilation for the atmosphere-ocean system, data assimilation for the atmosphere-land system and data assimilation for the land surface-subsurface system. Optimally exploiting observations in a compartment of the terrestrial system to update also states in other compartments of the terrestrial system still has strong methodological challenges. It is not yet clear that fully coupled approaches, where data are directly used to update states in other compartments, outperform weakly coupled approaches, where states in other compartments are only updated indirectly, through the action of the model equations. Coupled data assimilation allows to determine the value of different measurement types, and the additional value of measurements to update states across compartments. Another aspect of scientific interest for weakly or fully coupled data assimilation is the software engineering related to coupling a data assimilation framework to a physical model, in order to build a computationally efficient and flexible framework.

We welcome contributions on the development and applications of coupled data assimilation systems involving models for different compartments of the Earth system like atmosphere and/or ocean and/or sea ice and/or vegetation and/or soil and/or groundwater and/or surface water bodies. Contributions could for example focus on data value with implications for monitoring network design, parameter or bias estimation or software engineering aspects. In addition, case studies which include a precise evaluation of the data assimilation performance are of high interest for the session.

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 traditional stochastic, information-theoretical and dynamical analysis to 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 and analysis with physical understanding in mind.

NOTE: We are delighted to have Prof. Emanuele Borgonovo, from Department of Decision Sciences, Bocconi University as our invited speaker.

Session Description:
Proper characterization of uncertainty remains a major challenge, and is inherent to many aspects of modelling such as structural development, hypothesis testing and parameter estimation, and the adequate characterization of forcing data and initial and boundary conditions. To address this challenge, methods for a) uncertainty analysis (UA) that seek to quantify uncertainty (and how it propagates through a system/model), and b) the closely-related methods for sensitivity analysis (SA) that evaluate the role and significance of uncertain factors (in the functioning of systems/models), have proved to be very helpful.
This session invites contributions that discuss advances, both in theory and/or application, in methods for SA/UA applicable to all Earth and Environmental Systems Models (EESMs). This includes all areas of hydrology, such as classical hydrology, subsurface hydrology and soil science. Topics of interest include (but are not limited to):

1) Novel methods for effective characterization of sensitivity and uncertainty
2) Single- versus Multi-criteria SA/UA
3) Novel methods for spatial and temporal evaluation/analysis of models
4) The role of data information and error on SA/UA (e.g., input/output error, model structure error, etc.)
5) Novel approaches and benchmarking efforts for parameter estimation and data inversion
6) Improving the computational efficiency of SA/UA (efficient sampling, surrogate modelling, parallel computing, model pre-emption, etc.)

Contributions addressing any or all aspects of sensitivity/uncertainty, including those related to structural development, hypothesis testing, parameter estimation, forcing data, and initial and boundary conditions are invited.

Wed, 10 Apr, 12:45-14:00 / Room E1

Public information:
The dialogue between scientists, institutions, policymakers and the general public is widely recognised as an essential step towards a fair and sustainable society. Nowadays, more than ever in human history, international cooperation is an essential requirement for protecting the planet, advancing science and ensuring an equitable development of the global economy.
Despite its importance, the above dialogue can be a challenge for scientists, who often cannot find a productive connection with governments and politicians. Scientific associations are a key link between researchers and policy makers, as they have the potential to establish a durable and profitable connection with institutions.
The EGU elected the dialogue with society as one of its priority missions. At its General Assembly, the EGU is launching an innovative symposium format, Science and Society (SCS), to host scientific forums specifically dedicated to connecting with high-level institutions and engaging the public and policymakers.
The conversation with Ilaria Capua and Mario Monti will focus on science and politics with a global perspective, and the impact of populism on European integrity and therefore scientific research. The discussion will elaborate on optimal strategies to deliver topical and clear scientific messages to key institutions.
Ilaria Capua is a virologist best known for her research on influenza viruses and her efforts promoting open access to genetic information on emerging viruses. In 2006, Science reported on Capua’s effort towards open access science, stating that she had “renewed the debate about how to balance global health against scientists’ needs to publish and countries’ demands for secrecy". She has been a member of the Italian parliament from 2013 to 2016 and a fake news victim. She is currently a full professor at the University of Florida in Gainesville, Florida, US, and director of the UF One Health Center of Excellence.
Mario Monti served as a European Commissioner from 1995 to 2004, with responsibility for the internal market, services, customs, taxation and competition. He was Prime Minister of Italy from 2011 to 2013, leading a government of national unity to cope with the Italian debt crisis. Monti has also been Rector and is currently President of Bocconi University in Milan. His publications deal mainly with monetary and financial economics, public finance, European integration, competition policy. He is currently lifetime member of the Italian Senate.
During the conversation, Ilaria Capua and Mario Monti will present their vision with two 15-minute talks that will be followed by 20 minutes dedicated to questions from the audience and answers.

Plastic pollution is recognized as one of the most serious and urgent problems facing our planet. Rates of manufacture, use and ultimately disposal of plastics continue to soar, posing an enormous threat to the planet’s oceans and rivers and the flora and fauna they support. There is an urgent need for global action, backed by sound scientific understanding, to tackle this problem.

This Union Symposium will address the problems posed to our planet by plastic pollution, and examine options for dealing with the threat.

By accumulating precipitation at high elevations, snow and ice completely 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.

Specifically, contributions addressing the following topics are welcome:
- results of experimental research on snowmelt runoff processes and their potential implementation in hydrological models;
- development of novel strategies for snowmelt runoff modelling in various (or changing) climatic and land-cover conditions
- evaluation of observed in-situ or remote-sensing snow products (e.g. snow cover, albedo, snow depth, snow water equivalent) and their application for snowmelt runoff calibration, data assimilation or operational streamflow forecasting
- 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, high mountain regions, etc.
This session is linked closely to the session CR3.04/AS4.6/CL2.15/HS2.1.3 . While the focus of our session is on the monitoring and modelling of snow for hydrologic applications, session CR3.04/AS4.6/CL2.15/HS2.1.3 addresses monitoring and modelling of snow processes across scales.

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 linked closely to the session HS2.1.2/CR3.11. While the focus of our session is on monitoring and modelling snow processes across scales, session HS2.1.2/CR3.11 addresses monitoring and modelling of snow for hydrologic applications.

Water is a strategic issue in the Mediterranean region, mainly because of the rarefaction 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.

The tropics are characterized by greater energy inputs, higher rainfall variability compared to temperate and boreal environments and higher rates of environmental change. This results in extreme spatial and temporal uncertainties, including unpredictable patterns in soil moisture replenishment and groundwater recharge. Most tropical regions are hot spots for climate change and play important role in regional and global water, carbon and nutrient cycles. These ecosystems are susceptible to perturbations that include, but are not limited to, frequent and severe droughts and periods of extreme intense rainfall events. This environmental variability together with local hydro(geo)logical, geomorphological, and ecosystem factors are directly influencing the water quality and quantity, generating the increase in soil salinity as well as overgrazing and a general over-exploitation by humans, especially in years where resource availabilities are low.
Although modelling and novel observational techniques have been applied to develop cutting-edge research, their application remains cost prohibitive in the tropics. A robust data collection in the tropics is not feasible due mostly to economic and political shortcomings and, therefore, hydro(geo)logical and soil-plant-atmosphere processes across different scales in the tropics remain still poorly understood.

We invite field experimentalists and modellers who work in both wet and dry tropics to present their research on:
• Innovative observational techniques using sensors, hydrochemical and stable isotope tracers, plot and monitoring networks, citizen science, radars, and unmanned aerial vehicles;
• Modelling studies that use novel theories and data developed and applied to tropical catchments and ecosystems for a better understanding of the water fluxes from the plot to regional scales.

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.

Invited Speakers: James Kirchner, ETHZ, CH

Hydrological connectivity describes the degree of connection between and across landscape elements through water flow, and determines the ease with which water and solutes may move across the landscape or through a river system. Connectivity occurs across a wide range of spatial scales, from macropores to landscapes, and has been recognized as a first-order control on runoff generation, travel times, and solute transport. The concept of hydrological connectivity has the potential to enhance our understanding of hydrological processes, to link processes across scales and between field and modelling studies, and to provide a unifying framework to organize hydrologic behavior.

This session consists of two blocks: 1) a block that focuses on subsurface hydrological connectivity, linking hillslopes to the stream network and 2) a block that focuses on ephemeral and intermittent streams, including how surface connectivity in intermittent stream networks is established. We hope that together, these studies will enhance our understanding and stimulate discussions on how the concept of hydrological connectivity can be used to link surface and subsurface flows at the catchment scale.

We encourage contributions on all aspects of hydrological connectivity at the catchment scale or ephemeral and intermittent streams, including field studies and modeling studies on how, when and where connectivity is established, how stream networks expand and contract, and how this can be described or modeled, as well as the effects of connectivity or stream network expansion on stream water quantity and quality and stream biodiversity.

This will be a PICO session, which combines the advantages of oral and poster presentations. In addition to the initial 2-minute presentation to introduce the work and raise interest, authors have the opportunity to interact with the audience through the use of the PICO screens, which allows one to show videos, animations and pictures.

Invited speakers:

Luca Brocca from National Research Council, Research Institute for Geo-Hydrological Protection, Perugia, Italy, with the title "The missing information for hydrological modelling in agricultural areas: irrigation"

Martyn Clark from University of Saskatchewan, with the title "Modeling spatial patterns in hydrology: Neglected challenges."

Session Description: Hydrological models are formulations of hypotheses about natural systems' behavior. These formulations are constructed and refined to maximize the model fidelity, i.e., the agreement of the model with the reality. Models’ formulations (e.g., parameterizations) and set ups are based on both observations and qualitative expert knowledge encoded by means of mathematical or statistical tools. The interaction between data availability, expert knowledge and set of decisions that result in a working model is an important topic of discussion in scientific hydrological modeling. In this session, we welcome contributions which elaborate on the interaction between observations, expert knowledge and models with the aim of improving process understanding and the realism of our environmental models.

Potential contributions may include (but not limited to): (1) improving model structural adequacy given data and expert knowledge, (2) introducing new formulations for model components (constitutive functions) capturing the internal and external model fluxes or their overall behavior, (3) upscaling and applying the experimentalists' knowledge at catchment, basin or global scale, (4) investigating the added value of new sources of data, i.e., remotely sensed products, and new model set up or formulation to accommodate them, (5) novel methods that use the new sources of data to constrain or evaluate models, (6) better representation of often neglected processes in hydrological models such as human impacts, river regulations, irrigation, as well as vegetation dynamics, (7) better monitoring and seamless modeling of spatial patterns in hydrological and land surface models using hyper-resolution distributed earth observations, (8) identification and quantification of driving forces that generate spatial patters in these models, (9) and development of novel regionalization/regularization approaches and performance metrics for matching simulated hydrological states and fluxes with spatio-temporal data sources.

This session is organized as part of the grass-root modelling initiative on "Improving the Theoretical Underpinnings of Hydrologic Models" launched in 2016.

This session aims to discuss hydrology related to landslide occurrence both on local and regional scale. It focuses on the detailed analysis and modelling of hydrological processes on hillslope and catchment scale in order to improve our understanding and prediction of the spatio-temporal patterns of landslide triggering and slope deformation mechanisms.

Water circulation within a catchment and the resultant transient changes in both shallow and deep hydrological systems is the most common controlling and triggering factor of slope movements. However, incorporation of hydrological process knowledge in slope failure analysis, such as water-rock interaction, water storage, dynamic preferential flows or the influence of frost conditions to name a few, still lags behind. Also, the inclusion of regional hydrological information in rainfall thresholds analysis is underdeveloped. The research frontiers are connected with the complexity of real landslides such as the difficulty to monitor groundwater levels or soil moisture contents in unstable terrain and over large areas, the difficulty to understand the water pathways within heterogeneous regolith soils and fractured bedrock, which are the characteristic substratum where landslides occur, and the complexity of dynamically quantifying and predicting the hydrological exchange between a potentially unstable slope and its surroundings.

We invite research ranging from unsaturated zone, hillslope processes and regional hydrology which are applied to landslide research in a broad sense: ranging from soil slips to large scale deep-seated slope deformation. The session will give time to both laboratory and field monitoring studies, preferably quantitative, and based on novel measurement and modelling techniques. We invite pioneering research that includes hydrological information in local and regional hazard assessment. Moreover, we welcome studies that incorporate hydrological process knowledge in the geotechnical analysis and modelling setting the next step to improve landslide hazard analysis.

A large number of micropollutants and their transformation products (veterinary and human pharmaceuticals, personal care products, pesticides and biocides, chlorinated compounds, heavy metals, emerging contaminants such as PFASs) 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. Effective strategies to protect water resources from micropollutants are still lacking because the basic processes that contribute to their persistence and mobility in the aquatic environments are poorly understood. Innovative experimental studies in conjunction with modeling are urgently needed to fill these knowledge gaps to asses risks and develop remediation schemes.
This session invites contributions that improve our quantitative understanding of the sources and pathways, mass fluxes, the fate and transport of micropollutants in the soil-groundwater-river continuum. Topics cover:
- Novel sampling and monitoring concepts and devices
- New analytical methods for micropollutants such as 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

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

Agriculture intensification causes worldwide increase of rivers, lakes and groundwater aquifers pollution. Pollutants may originate from various sources related to different types of agriculture activities including cultivation, aquaculture, livestock and dairy farms and related food-processing industries, and partitioning their respective contribution to water bodies remains challenging. Degradation of water quality is associated with both macronutrients and micro-pollutants originating from the inefficient use of chemical and organic fertilizers, and transport and persistence of pesticides and antibiotics. Therefore, identification of spatial and seasonal variations of pollutant sources and loads at the catchment scale is critical for better understanding human and environmental impacts of agro-contaminants, and eventually improving land management practices to protect water quality.

This session is focused on the use of hydro(geo)chemical and stable isotope tracers in quantifying agro-contaminant sources and transport but other related studies are also welcome. We especially encourage submissions in the following topics:
• Application of multi-isotope tracer techniques to constrain sources
• Catchment-scale pollution budget and predictive modelling
• Nonpoint agriculture source pollution partitioning at different catchment scales
• Identifying sources of macronutrients and micropollutants: macronutrients, herbicides, fungicides and insecticides, antibiotics, rare earth elements
• Distinguishing agro-contaminants from other pollution sources at the catchment scale
• Agriculture land use and agro-contaminants diversification

Public information:
Poster attendance time: Tuesday, 9 April 2019, 14:00–15:45 | Hall A
!Join us! Active poster sessions: a poster walk-through is organized at 14:15, poster authors will have 1–2 minutes to present their poster.

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. Contaminants are dispersed in river catchments by a variety of physical, chemical and biological pathways and processes. This session is devoted to research that aims to characterize and quantify: (1) source areas which contribute contaminant mass, (2) transport processes which move contaminants from source areas to and through affected water bodies such as streams, rivers, lakes, wetlands, and groundwater, (3) biogeochemical processes which attenuate and/or transform contaminants, and (4) the interaction of contaminants with biota and ecosystems. Submissions from a variety of subfields are welcome, including research into mine water treatment and mine waste remediation practices. We also welcome submissions that focus on a variety of contaminant types including, but not limited to, metals, metalloids, rare earth elements and sulfate.

The following invited speakers have been confirmed: Professor Karen Hudson-Edwards (Camborne School of Mines, University of Exeter, UK) and Dr Rory Cowie (Mountain Studies Institute, Colorado, USA).

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.

Keynote speaker:
Prof Peter Reichert: “The need for Bayesian approaches in water research and management.”
Eawag, Swiss Federal Institute of Aquatic Science and Technology; Department of Systems Analysis, Integrated Assessment and Modelling

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 flowpath contributions 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
- Long-term changes of nutrient inputs, outputs and apparent nutrient travel times
- Co-variance of solute and particulate concentrations and their ecohydrological controls
- Instream processes and river network effects on solute concentrations
- Utilizing time series of compound-specific isotopic fingerprints
- Time series analysis of emerging contaminants such as pesticides or micropollutants

Snow and ice can capture and store contaminants both local and global in origin. The decrease in glacier cover, snow cover and sea ice in response to climate affects cycling of airborne impurities in polar and alpine environments, accelerating and enhancing their release. In this context snow and ice act as a secondary source for numerous organic and inorganic atmospheric contaminants that were deposited on their surface during recent decades, including persistent organic pollutants, radioactive species, microplastics, pesticides, and heavy metals. The release of contaminants from snow and ice to glacier forefields, rivers and seas might pose a hazard to these ecosystems and to human health, particularly under accelerated melt conditions.

Identification and assessment of this hazard relies, for each contaminant class, on the understanding of processes that control their accumulation, release and downstream transport. The physical and chemical forms in which contaminants are removed from the atmosphere and hydrosphere may further affect their interactions with mineral substances and biota. Existing studies suggest that the contaminant release process is not linear, and that interactions between meltwater, supraglacial debris and glacial microbiology may be crucial in the accumulation and transport of contaminants in glacier catchments. For example, evidence is mounting that cryoconite can efficiently accumulate radionuclides from anthropogenic sources to potentially hazardous levels in glaciers around the world. At the same time, the high biological activity present in cryoconite could enhance the degradation of organic pollutants, with important implications for remediation. A portion of contaminants released from glaciers may also be stored in their proglacial zones as shown by the very high concentrations of radionuclides found by several recent studies. The effects of contaminant transport on the pro-glacial environment and downstream communities remain uncertain, but improved understanding of the impacts of contaminants in land ice, sea ice, and snow is clearly warranted.

The session aims to contribute to the development of this emerging and interdisciplinary field, welcoming presentations from across cryospheric, hydrological, and biogeochemical sciences, and other research areas.

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".

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, changes of economic, societal and technological drivers, flood vulnerability, among others.

- Future flood risk changes and adaptation and mitigation strategies

Catchments are systems that often consist of an organized architecture of typical patterns of topography, soils, vegetation and flow networks. These patterns are largely the geomorphic, and biologic response to temporally and spatially variable environmental conditions or human interference. This organization of catchment components controls the storage and release of water and nutrients. Consequently, understanding catchment organization is critical for:

- Creating catchment models that balance necessary complexity with possible simplicity,
- Understanding the degree of similarity between catchments, with the prospect of developing hydrological theories that are transferable in space and/or time,
- Increasing our understanding of catchment processes and behavior across various spatial and temporal scales, and
- Predicting the future evolution of catchment properties and hydrologic response in a non-stationary environment.

In this session we bring together catchment hydrologists and stream-/ecohydrologists who study these topics at different scales. We present experimental and modeling studies that analyze the role of catchment storage, catchment mixing and hyporheic exchange fluxes and determine how they control hydrologic and hydrochemical catchment response in time and space.

Solicited Speakers: Federica Remondi, ETH Zürich
Gonzalo Miguez-Macho, Universidade de Santiago de Compostela, Spain

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.

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.

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 papers 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: droughts, floods;

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

Large samples of catchments can provide insights into hydrological processes that cannot be obtained from small samples. This session aims 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. Landscape characterisation - hydrological processes are shaped by the interplay of landscape attributes such as topography, climate, vegetation, soil, geology: how to better understand this interplay using available data sets?
2. Generalisation from the catchment to continental scale: 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, including across borders
4. Quantification and synthesis of data quality and uncertainty, including across borders
5. Identification and characterisation of dominant hydrological processes with limited data: how far can we get using hydrological signatures?
6. Human intervention and land cover changes: how to characterise and account for these processes in large-sample studies?
7. 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. Our invited speaker for 2019 is Vazken Andreassian.

In addition to this session, we will organise a splinter meeting to discuss and coordinate the production of large-sample data sets. Following a similar meeting at EGU 2018, it will be entitled “Large sample hydrology: facilitating the production and exchange of data sets worldwide”, its location and date will be indicated in the final programme.

The session and the splinter meeting will be organised in the framework 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, remote sensing, observation data or combination of these. They attempted to estimate the amount of water that evapotranspires, runs-off into the Ocean or is retained in water storages on the terrestrial part of the Earth. However, previous estimates in literature e.g. on global scale river discharge differ largely due to the methodology and datasets used for calculation such that a robust assessment of the global and continental water balance components is challenging both in a historical period and future projections. This session is seeking for contributions that are focusing on the
i) assessment of global, continental and regional scale water balance components, such as precipitation, river discharge to the oceans (and/or inland sinks), evapo(transpi)ration, groundwater recharge, water use, change in water storage from the land and / or Ocean part of the Earth,
ii) presenting innovative approaches of such assessments,
iii) presenting the uncertainty of estimated water balance components.
We encourage submissions using different methodological approaches, such as (but not limited to) observation data driven analyses, global scale hydrological and land surface models (GHMs, LSMs), integrated atmosphere, Ocean-Land modeling (Earth System Models), remote-sensing approaches, isotope analyses, thermodynamic borders and meteorological/climate approaches such as energy balance driven water balance. Contributions could focus on any of the water balance components or in an integrative manner, for either Land, Ocean or both. Assessments of uncertainty of water balance components are highly welcome.

Geodesy is becoming increasingly important for observing the hydrological cycle and its effects on solid Earth shape. Signals in geodetic data have revealed water's influence on other geophysical processes including earthquakes, volcanos, land subsidence, mountain uplift, and other aspects of long- and short-term vertical land motion. GPS and InSAR measurements, for example, respectively provide high temporal and spatial resolution to study natural hydrologically-related deformation and monitor anthropogenic groundwater extraction and recharge, and GRACE is helping to track changes in the global terrestrial water storage. Signals of loading from changes in surface and groundwater storage are seen from basin to continental scale. Additionally, novel use of GPS reflectometry is operational for monitoring soil moisture and snow depth at continuous GPS stations in the western USA and Canada. We encourage contributions describing new observations and models of hydrological signals in geodetic time series and/or imaging. These include but are not limited to studies exploring deformation induced by loading, aquifer extraction/recharge, poroelastic deformation and stress changes, techniques for removing hydrological signals from geodetic datasets, monitoring water resources, or teleconnections between hydrologic and other geophysical phenomena.

A wide range of processes in the earth system directly affect geodetic observations. This session invites a wide array of contributions which showcase the use of geodesy for Earth science and climate applications, providing crucial insights into the state and change of the earth system and/or understanding its processes.

Data driven quantification of water mass fluxes through boundaries of Earth’s different regions and spheres provides important insights to other geoscience communities and informs model validation and improvement. Changes in regional sea level and ocean circulation are observed by altimetry and gravimetry. Natural and anthropogenic alterations of the terrestrial water cycle lead to changes in river runoff, precipitation, evapotranspiration, and water storage which may cause surface deformation sensed by GNSS stations and InSAR measurements as well as mass/gravity changes observed by satellite/ground gravimetry. Mass changes in the ice sheets and glaciers are detectable by both geometrical and gravimetric techniques. And other novel applications of geodetic techniques are emerging in many fields.

In addition, individual sensor recordings are often affected by high-frequency variability caused by, e.g., tides in the solid Earth, oceans, and atmosphere and their corresponding crustal deformations affecting station positions; non-tidal temperature and moisture variability in the troposphere modifying microwave signal dispersion; rapid changes in the terrestrially stored water caused by hydrometeorologic extreme events; as well as swift variations in relative sea-level that are driven by mass and energy exchange of the global oceans with other components of the Earth system, which all might lead to temporal aliasing in observational records. 

This session invites a wide array of contributions which showcase the use of geodesy for Earth science and climate applications. This session aims to cover innovative ways to use GRACE, GRACE-FO and other low Earth orbiters, GNSS techniques, InSAR, radar altimetry, and their combination with in-situ observations. We welcome approaches which tackle the problem of separating signals of different geophysical origin, by taking advantage of model output and/or advanced processing and estimation techniques. Since the use of geodetic techniques is not always straightforward, we encourage authors to think of creative ways to make their findings, data and software more readily accessible to other communities in hydrology, ocean, cryospheric, atmospheric and climate sciences. With author consent, highlights from the oral and poster session will be tweeted with a dedicated hashtag during the conference in order to increase the impact of the session.

Hydroinformatics has emerged over the last decade 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, high-performance computing, systems science and computational intelligence tools. It provides the computer-based decision-support systems that are now entering more and more into the offices of consulting engineers, water authorities and government agencies. Tools for capturing data, on both a mega-scale and a milli-scale, are immense and still emerging. As a result we 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 and data science: neural networks, fuzzy systems, support vector machines, genetic programming, cellular automata, chaos theory, etc.
* Methods for the analysis of complex data sets, including remote sensing data: principal and independent component analysis, feature extraction, time series analysis, data-infilling, information theory, etc.
* Specific concepts and methods of Big Data and Data Science such as data thinning, data fusion, information integration
* Optimisation methods associated with heuristic search procedures: various types of genetic and evolutionary algorithms, randomised and adaptive search, ant colony, particle swarm optimisation, 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
* Appropriate software architectures for linking different types of models and data sources
* Opportunities and challenges in using high-performance computing for terrestrial systems modelling.

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.

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.

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 novel approaches of spatio-temporal and/or geostatistical analysis to assess, predict, and manage water related and/or interlinked hazards including the assessment of uncertainties.

The aim of this session is to provide a platform and an opportunity to demonstrate and discuss innovative applications and methodologies of spatio-temporal and/or geostatistical analysis in a hydrological 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.

Given the broad scope of this session, the topics of interest include the following non-exclusive list of subjects:

1. Spatio-temporal methods for the analysis of hydrological, environmental and climate anomalies and/or related hazards.
2. New and innovative geostatistical applications in spatial modeling, spatio-temporal modeling, spatial reasoning and data mining.
3. Spatio-temporal and/or geostatistical methods with reduced computational complexity suitable for large-size hydrological problems.
4. Spatio-temporal dynamics of natural events (e.g. morphological changes, spatial displacement phenomena, other).
5. Generalization and optimization of spatial models including monitoring networks optimization.
6. Applications of copulas on the identification of spatio-temporal relationships.
7. Spatial switching and/or ensemble of models.
8. Spatial analysis and predictions using Gaussian and non-Gaussian models.
9. Spatial and spatio-temporal covariance application revealing links between hydrological variables and extremes.
10. Prediction on regions of unobserved or limited data where gridded and point simulated data from physical-based models is available.
11. Generalized extreme value distributions used to model extremes for spatial event analysis.
12. (Geostatistical) characterization of uncertainties.
13. Bayesian Geostatistical Analysis.

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.

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, including deep learning and other advanced approaches
• Visualization and visual analytics of big data
• Informatics and data science
• Emerging big data paradigms, such as datacubes

Many situations occur in Geosciences where one wants to obtain an accurate description of the present, past or future state of a particular system. Examples are prediction of weather and climate, assimilation of observations, or inversion of seismic signals for probing the interior of the planet. One important aspect is the identification of the errors affecting the various sources of information used in the estimation process, and the quantification of the ensuing uncertainty on the final estimate.

The session is devoted to the theoretical and numerical aspects of that broad class of problems. A large number of topics are dealt with in the various papers to be presented: algorithms for assimilation of observations, and associated mathematical aspects (particularly, but not only, in the context of the atmosphere and the ocean), predictability of geophysical flows, with stress on the impact of initial and model errors, inverse problems of different kinds, and also new aspects at the crossing between data assimilation and data-driven methods. Applications to specific physical problems are presented.


Solicited Speakers
Olivier Pannekoucke (Météo-France, Toulouse)
Manuel Pulido (University of Reading)

This interdisciplinary session welcomes contributions on novel conceptual approaches and methods for the analysis of observational as well as model time series and associated uncertainties 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

We particularly encourage submissions addressing the problem of uncertainty of geoscientific time series and its treatment in the context of statistical and dynamical analysis, including:
- representation of time series with uncertain dating (in particular paleoclimatic records from ice cores, sediments, speleothems etc.)
- uncertainties in change point / transition detection
- uncertainty propagation in time series methods like correlation, synchronization, spectral analysis, PCA, networks, and similar techniques
- uncertainty propagation in empirical (i.e., data-derived) inverse models

Drought and water scarcity are important issues in many regions of the Earth, requiring innovative hydro-meteorological monitoring, modelling and forecasting tools to evaluate the complex impacts on the availability and quality of water resources. While drought describes a natural hazard, water scarcity is related to long-term unsustainable use of water resources and associated socio-economic aspects. Both phenomena are, however, closely linked, with the complex interrelationship requiring careful attention.
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. Particular attention should, therefore, be paid to the feedbacks between these two phenomena, including the potential impacts of climate change. 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 will address 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, policy makers and other stakeholders, are further issues to be 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.

Many water management sectors are already having to cope with extreme weather events, climate variability and change. For this purpose, climate services provide science-based and user-specific information on possible impacts. Such information can be based on weather forecasts or on climate projections. In this context, predictions on sub-seasonal, seasonal to decadal timescales are an emerging and essential part of hydrological forecasting. With horizons ranging from months to a decade, these probabilistic forecasts are used in industries such as transport, energy, agriculture, forestry, health, insurance, tourism and infrastructure.

This session aims to cover the advances in climate and hydrological forecasting, and their implications on forecasting extreme events and servicing water users. 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,
- Effective methods to link stakeholder interests and scientific expertise,
- Operational climatic forecasting systems.

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.

Intense rainfall and/or orographic 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. Under appropriate topographic conditions, such rainstorms also cause debris flows or shallow landslides mobilizing large amounts of unconsolidated material. Although significant progress has been made in the last decade in the management of flash floods related risks, these events remain poorly understood and their predictability is limited by a high non-linearity in the hydrological response, related to threshold effects and structured heterogeneity at all scales. In addition, predicting the initiation and runout of rainfall-induced landslides and their interactions with hydrological and hydraulic processes is still affected by large uncertainties. Therefore, improving the flash floods understanding, forecasting and risk management capacities requires multi-disciplinary approaches, as well as innovative measurements and modelling approaches as these events often occur in ungauged basins.

This session welcomes contributions illustrating current advances and approaches in monitoring, modelling, forecasting and warning flash floods and associated geomorphic processes. Contributions documenting the societal responses and impacts, and analysing risk management systems are also welcome. The session will cover the following main scientific themes:
- Development of new measurement techniques adapted to flash floods monitoring and quantification of the associated uncertainties
- Use of remote sensing data, weather radar, and lightning for improving forecasting models input data
- Development of modelling tools for predicting and forecasting flash floods and/or rainfall-induced landslides in gauged and ungauged basins
- Use of new criteria such as specific “hydrological signatures” for model and forecast evaluation
- Identification of processes leading to flash flood events and/or rainfall-induced landslides from data analysis and/or modelling, and of their characteristic space-time scales
- Evolutions in flash-flood characteristics possibly related to changing climate.
- Observation, understanding and prediction of the social vulnerability and social response to flash floods and/or associated landsliding
- Flash flood and/or rainfall-induced landslide risk assessment using multi-disciplinary approaches and warning systems, and evaluation of the relevance of those systems.

Several large ensemble model simulations, either from Global Climate Models (GCM), Earth System Models (ESM), or Regional Climate Models (RCM), have been generated over the recent years. These ensembles, typically simulating historical climate and making future projections, are powerful because they can be used to accurately estimate forced changes in the climate system and to determine the magnitude and realism of simulated internal climate variability. They can further be applied to investigate how climate change signals may emerge from internal variability over time. Combining large ensemble simulations also provides long time series to investigate the dynamics of hydro-meteorological extremes and to assess compound events (e.g., successive or simultaneous extreme events) under conditions of climate change.

This session invites studies using large GCM, ESM, or RCM ensembles looking at the following topics: 1) forced changes in internal variability and reinterpretation of observed record; 2) development of new approaches to attribution of observed events or trends; 3) impacts of natural climate variability; 4) assessment of extreme event occurrence in historical and future climate; 5) development of projections for compound events; 6) comparison of large ensembles including uncertainty assessment; and 7) novel methods for efficient analyses and post-processing of large ensembles.

We welcome research across the components of the Earth system and particularly invite studies that apply novel methods or cross disciplinary approaches to leverage the potential of large ensembles.

Today, it is almost certain that global climate change will affect the frequency and severity of extreme meteorological and hydrological events. It is necessary to develop models and methodologies for the better understanding, forecasting, hazard prevention of weather induced extreme events and assessment of disaster risk. This session considers extreme events that lead to disastrous hazards induced by severe weather and climate change. These can, e.g., be tropical or extratropical rain- and wind-storms, hail, tornadoes or lightning events, but also floods, long-lasting periods of drought, periods of extremely high or of extremely low temperatures, etc. Papers are sought which contribute to the understanding of their occurrence (conditions and meteorological development), to assessment of their risk and their future changes, to the ability of models to reproduce them and methods to forecast them or produce early warnings, to proactive planning focusing to damage prevention and damage reduction. Papers are also encouraged that look at complex extreme events produced by combinations of factors that are not extreme by themselves. The session serves as a forum for the interdisciplinary exchange of research approaches and results, involving meteorology, hydrology, hazard management and/or applications like insurance issues.

Ensemble hydro-meteorological prediction systems have higher forecasting skills than their deterministic counterparts, which in turn can improve risk assessment decision-making in operational water management. Ensemble forecasts are now common many operational settings, such as flood and drought forecasting, and can be used in applications from forecasting extreme events to optimisation of water resources allocation. However, moving from deterministic forecasting systems to a probabilistic framework poses new challenges but it also opens new opportunities for the developers and users of ensemble forecasts to improve their systems.

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. The session will also explore new forecast products and systems in terms of their implementation and practice for real-time forecasting.

Contributions will cover, but are not restricted to, the following topics:
- The design of ensemble prediction systems
- Requirements and techniques to improve the skill of hydro-meteorological ensemble forecasting systems
- Methods to bias correct and calibrate ensemble forecasts
- Methods to assess the quality or benchmark the performance of ensemble forecasts
- Approaches to deal with forecast scenarios in real-time
- Strategies for balancing human expertise and automation in ensemble forecasting systems
- Challenges of the paradigm shift from deterministic to ensemble forecasts
- Methods and products that include forecaster knowledge to improve the interpretation of ensemble forecasts
-Use of cost/loss scenarios for optimising systems
- Approaches for efficient training (including role-playing games) on the use and value of ensemble predictions.

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.

Solicited speaker Niko Wanders from Utrecht University: From seasonal forecasting to water management decisions: challenges and opportunities

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

This session will address the understanding of sources of predictability and quantification and reduction of predictive uncertainty of hydrological extremes in operational hydrologic forecasting. Including 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. Providing uncertainty estimates for integrated catchment models involving forecasting models, either as a cascade or as alternative models, can prove particularly challenging and are an issue of interest to the session. Data assimilation or pre-/post-processing in real-time can provide important ways of improving the quality (e.g. accuracy, reliability) and reducing the uncertainty of hydrological forecasts. Methods that help update forecasts in real-time to reduce bias and increase accuracy, and case study demonstrations of their use, are of interest to this session.
The models involved with the methods for predictive uncertainty, data assimilation, post-processing and decision-making may include catchment models, runoff routing models, groundwater models, coupled meteorological-hydrological models as well as combinations of these. Demonstrations of the sources of predictability and subsequent 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.
Contributions are expected to address the following issues:
(i) Sources of predictability (model, forcing, initial conditions)
(ii) Quantification and reduction of predictive uncertainty
(iii) Real-time data assimilation
(iii) Untangling sources of uncertainty in the meteorological-hydrological forecasting chain
(iv) Effect of (improved) representation of model process on forecast quality and predictive uncertainty
(v) Methods for preparing meteorological predictions as input to real-time hydrological probability forecasts
(vi) Verification (methods) of hydrologic forecasts
(vii) Case studies of the above

Solicited speaker is Maurizio Mazzoleni (from Uppsala University) who will give a talk about Real-time assimilation of crowdsourced observations in hydrological and hydraulic models.

Prediction skill of hydro-meteorological forecasting systems has remarkably improved in recent decades. Advances in both weather and hydrology models, linked to the availability of more powerful and efficient computational resources, allowed the development of even more complex systems based on the combination of spatially distributed physically-based hydrologic- and hydraulic models with deterministic and/or ensemble meteorological forecasting systems. Coupled atmosphere-hydrological modeling aims at describing the full atmospheric-terrestrial regional water cycle, i.e. extending from the top of the atmosphere, through the boundary layer, via the land surface and subsurface till lateral flow in the groundwater and in the river beds. Fully two-way coupled model systems thereby give the possibility to study long range feedbacks between groundwater, soil moisture redistribution and precipitation. Via improved and completed process descriptions fully coupled modeling may also increase the performance of hydrometeorological predictions of various spatial and temporal scales.
The objective of the session is to create a valuable opportunity for the interdisciplinary exchange of ideas and experiences among atmospheric-hydrological modelers and members of both hydrology- and Earth System modeling communities. Contributions are invited dealing with the complex interactions between surface water, groundwater and regional climate, with a specific focus on those presenting work on the development or application of one-way (both deterministic and ensemble) or fully-coupled hydrometeorological prediction systems for floods/flash-floods, droughts and water resources. Presentations of inter-comparisons between one-way and fully-coupled hydrometeorological chains are encouraged, such as contributions on novel one-way and fully-coupled modeling systems that bridge spatial scales through dynamic regridding or upscaling/downscaling methodologies. Also, presentations addressing data assimilation in coupled model systems are welcome. Likewise abstracts are invited on field experiments and testbeds equipped with complex sensors and measurement systems allowing multi-variable validation of such complex modeling systems.

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 now 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.

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.

This interactive PICO 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, and ensemble forecasting. However, once a system is operational, the development often continues more in the field of applied research or consultancy. Furthermore, development of these types of systems is usually performed within one field of expertise. Forecasting warning research can be more effective when these efforts and experiences are combined.

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 monitoring of data, analysing data, making forecasts, giving warning signals and suggesting response measures.

Contributions addressing the following topics are welcome:
- Applications of forecasting warning systems for water-related natural hazards, such as: flood, drought, tsunami, landslide, hurricane etc.
- Applications of forecasting warning systems for other hazards, such as: pollution
- Operational data validation and calibration
- Operational warning methods and procedures
- Real time control for hazards
- The operational system as a tool for improved risk management and decision making
- Performance of operational forecasts, event analysis
- Serious games and training with operational systems
- Structure of operational forecasting systems
- Techniques/applications to better communicate forecasts with users - such as visualization tools and impact assessments
- Impact-based forecasts for early action, response and control.

The occurrence of extremes such as droughts, flash floods, hailstorms, storm surges and tropical storms can have significant and sometimes catastrophic consequences to society. However, not all low probability weather/climate events will lead to “high impacts” on human or natural systems or infrastructure. Rather, the severity of such events depend also intrinsically on the exposure, vulnerability and/or resilience to such hazards of affected systems, including emergency management procedures. Similarly, high impact events may be compounded by the interaction of several, e.g., in their own right less severe hydro-meteorological incidents, sometimes separated in time and space. Or they may similarly result from the joint failures of multiple human or natural systems. Consequently, it is a deep transdisciplinary challenge to learn from past high impact events, understand the mechanisms behind them and ultimately to project how they may potentially change in a future climate.

The ECRA (European Climate Research Alliance) Collaborative Programme on “High Impact Events and Climate Change” aims to promote research on the mechanisms behind high impact events and climate extremes, simulation of high impact events under present and future climatic conditions, and on how relevant information for climate risk analysis, vulnerability and adaptation may be co-created with users, e.g., in terms of tailored climate services. For this aim, this Interdisciplinary and Transdisciplinary Session invites contributions that will serve to (i) better understand the mechanisms behind high impact events from a transdisciplinary and interdisciplinary perspective, e.g. case studies and the assessment of past high impact events, including detection and attribution; (ii) project changes to high impact events through, e.g. high resolution climate and impacts modelling (including economic modelling); (iii) produce climate information at the relevant scales (downscaling); and co-create climate services with users to help deal with the risk and/or impacts of high-impact events, e.g. risk analysis and climate adaptation. Abstracts that highlight recent advances from a transdisciplinary perspective for example through the innovation of climate services will be particularly encouraged. Authors and contributors to this session will be offered to present their work in a Special Issue of the journal “Sustainability”.

Growing human population, urbanization, and changing availability of freshwater resources are expected to impact on urban and rural water systems in the next years, with emphasis on changing demand magnitude, peaks, and spatial and temporal patterns, and related water availability, supply capabilities and operations.
This context, coupled with the technological development and diffusion of advanced metering technologies, intelligent sensors, increasing data availability, and automatic or real-time control of water distribution networks, is opening up new opportunities to advance methods and applications for water demand and supply network analysis, modelling, and management. Along with such technological developments, transdisciplinary approaches that include economic, societal and environmental components are key to ultimately support and innovate traditional planning and management operations of water resources in urban and rural systems, at various temporal and spatial scales.
This session aims to provide an active forum to discuss and exchange knowledge of consolidated and emerging transdisciplinary approaches, frameworks, methods, tools, and technologies contributing to the state-of-the-art water demand and supply network analysis, modelling, and management, and demonstrate their potential or proved impact onto real-world applications.
Topics and applications could belong to any area of urban and rural water systems management, with a special focus on transdisciplinary approaches, including technological advances (e.g., monitoring sensors, intelligent sensors, big-data analysis and information retrieval, anomaly detection, and cybersecurity), behavioural analysis and societal aspects, descriptive and predictive models of water demand, experimental approaches to demand management, water demand and supply optimization.

Globally, we are facing massive challenges on how we manage our catchments, in both rural and urban areas, in the next decades. With a changing climate and increased pressure on our land resources we need to ensure we manage the water in our catchments more sustainably and even more so during hydro-climatic extremes. Nature-based solutions (NBS) are 'living' solutions inspired by and continuously supported by nature or natural processes. NBSs are designed to address various societal challenges in a resource efficient and adaptable manner to provide simultaneously economic, social and environmental benefits (European Commission 2015). Therefore NBS can be used within both rural and urban areas to mitigate catchment flood risk, provide drought resilience, protect and enhance endangered freshwater ecosystems and reduce diffuse pollution. However, there are still challenges in implementing NBS for reasons such as lack of evidence surrounding the effectiveness (e.g. at larger scales) and for delivering multiple benefits.

Therefore this session focuses on key research and policy questions associated with NBS. For example, how do we develop locally adapted solutions in catchments and urban areas? What are the impacts of these measures at larger scales (e.g. sub-catchment/ catchment scale)? How can we address multi-disciplinary benefits? How can we do more for less? Importantly, how can we provide the evidence base around the concept of Nature Based Solutions for managing hydrological extremes and water resource management? Examples of studies that cover either the management of flooding, drought, water quality or ecology (both in the rural, peri-urban and urban context) using NBS approaches are at the heart of this session. Management measures could include techniques such as Green Infrastructure, Natural Water Retention Measures, Natural Flood Management, Catchment Restoration, Ecological Engineering or Blue-Green Infrastructure. We invite (but not limit to) abstracts that demonstrate good quality hydrological experiments around NBS; that develop new or improve existing modelling approaches/decision support tools; that investigate and quantify the multiple benefits; and which explore the challenges of implementation (e.g. stakeholder uptake/economics/cost benefit).

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.
Public information:
Publication of contents in a special issue is foreseen. Contributions from previous years were published in the Special Issue “Advanced Tools for Integrated Water Resources Management” (Science of the Total Environment (STOTEN, Elsevier, doi:10.1016/j.scitotenv.2016.12.051), and in the STOTEN Book Series “ Advances in Chemical Pollution, Environmental Management and Protection” (https://tinyurl.com/y8f9favj).

Water plays a critical role in sustaining human health, food security, energy production, and ecosystem services. Population growth, climate change, and socio-economic and land use developments increasingly threaten water quality and quantity. The success of water resources policy and management is dependent on the integrative understanding of coupled human environmental systems and a careful consideration of uncertainty. Only through such integrative understanding is it possible to generate practical, scientifically sound, and socially acceptable solutions that are sustainable. The careful consideration of the implication of uncertainty is necessary if solutions are to be not just acceptable and sustainable, but also robust over a wide range of plausible future developments. This session provides a forum for discussing the advances in water resources systems analysis, planning and management under uncertainty for informing the planning, policymaking, and management of water resources in a changing world.

The research field of socio-hydrology emerged recently 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 and epistemologies: from the air (remote sensing), on the ground (empirical field studies) and in the laboratory (modelling) and from positivist thinking common in natural and engineering sciences and constructivist thinking common in social sciences and behavioural economics.

The session therefore aims to trigger a discourse on understanding such systems at a diversity of scales with mutual recognition of different epistemologies within natural and social sciences. Examples of feedbacks include, but not limited to, economic forces such as agricultural or industrial production, diffusion or adoption of technology and knowledge such as water harvesting, community awareness such as emergence of environmental movements, values and norms etc. 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 of theoretical, conceptual or applied nature are solicited that 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”.

Public information:
This session proudly hosts the HS Division Outstanding Early Career Scientists Award presentation by Serena Ceola. She was awarded for her outstanding contributions to the understanding of the interplay of river dynamics, fluvial ecology and human activities.

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). Advances in modeling, optimization, and control will play an essential role in providing these solutions.

This session is intended for contributions on the technical aspects of modelling and control of environmental systems for a future, where complex real time coordination between different sub-systems will be the rule rather than the exception.

Examples of topics suitable for this session are:

• models of both environmental systems and of management practices that can be used to study the effects of new control algorithms;
• models and algorithms for adaptive and resilient operational management of environmental systems;
• innovative solutions that exploit synergies and avoid potential conflicts for multi-resource and multi-sector systems.


The session is associated with Panta Rhei working group "Natural and man-made control systems in water resources" and welcomes contributions addressing the above mentioned points, especially in the context of hybrid power systems and water resource systems used for irrigation, drainage, water supply (potable water, industrial water, cooling water) and transport of goods.

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.

The transition to a low-carbon economy and programs of nuclear power phase-out 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, and flood control tend to reduce the ability of hydropower to integrate variable renewable. In this context, energy production relies on reliable short and long term predictions of the temporal availability and the quality of natural resources (water, wind, solar power etc).

This session solicits contributions that describe, characterize, or model distributed renewable energy sources at different spatial and temporal scales that are relevant for the electricity systems, their interactions, their planning and management. Spatial scales range from point scale (i.e. stand-alone system) to national and international scales. Temporal scales range from minutes to decades. 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, including experimental work to understand how energy production affects ecosystems.

We hope that the contributions to this session will highlight how hydrology and closely related methods can contribute to address urgent challenges in this field.
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 to predict and quantify the influence of climate change on climate-related energies and the energy demand?
- How to quantify the relevant impacts on the hydropower sector?
- What energy-source transitions occur in view of climate and global change? How can they be modelled? How do energy, land use and water supply interact during transitions?
- How socio-economic aspects can be taken into account when modelling renewable energy sources?
- 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, quantification of residual flow impacts on river ecosystems.

Developing a sustainable future requires the optimal integration and synergising of energy, agriculture and water sectors. As developing economies grow with rapid urbanisation, access to modern energy and water services should grow sustainably. Quantitative tools for planning and assessing national and basin scale infrastructure planning are essential for this. Issues of access and the challenges of biophysical and socioeconomic dynamics involved therein are often poorly reflected in plans. Integrated Assessment Modeling (IAMs) can allow for studying interactions between the economy, water use, energy use, and the environment. IAMs enable investigating long-term transition pathways in the context of climate change and shared socioeconomic pathways.

Most IAMs, however, are mainly global and at best regional, and as such do not adequately represent socio-hydrological mechanisms at smaller scale. On the other hand, basin scale studies often poorly reflect national and regional drivers. One of the main bottlenecks is the intrinsic difficulty in bridging the high-level system-oriented approach of IAMs with the strong dependency of the efficacy of plans on local socioeconomic and hydrological drivers. We invite contributions connecting fundamental and applied research for policy making, concepts and case studies to better understand how IAMs can be better utilised in infrastructure decisions at regional, country or basin scales.

Keys: Integrated Assessment Modelling, Water-Energy-Food Nexus, Infrastructure Decisions, Urbanization, Climate Change

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, being co-dependent on changing weather patterns such as the frequency and magnitude of storms, the periodicity of droughts, land modifications and response time lags; leading to water quality degradation, risk 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. While high frequency monitoring and/or long time series have improved our process-based understanding of pollutant losses to water at catchment level, 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.

To this end, 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 and draw on all available information from expert knowledge to high resolution data sets.

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.

Keynote speaker:
Prof Peter Reichert: “The need for Bayesian approaches in water research and management.”
Eawag, Swiss Federal Institute of Aquatic Science and Technology; Department of Systems Analysis, Integrated Assessment and Modelling

Synergistic approaches to respond to water, food and energy increasing needs, incorporating the need to hinder impacts on the environmental (land) and socio-economic realities, are essential to attain the UN Sustainable Development Goals 2, 6, 7 and 15. Such nexus approach is highly challenging given the substantial and highly contextual interdependencies between sectors. It becomes more daunting if we consider the need to adapt to climate change.

In response to this global development challenge, this session brings together the community of engineers, scholars, scientists and decision makers, with a common interest on novel frameworks and methodologies for an integrated water resources management taking into account its connections to energy production, land use and impacts and societal implications in a context of climate change adaptation. We discuss improved approaches for water related nexus, which not only considers the effects in the geophysical system (water, sediment, landscape) but also further implications related to socio-economic and ecological spheres. The works presented contain conceptual and applied models with references to energy production, engineering response, management, nature protection, agriculture and society. New approaches to analyse and manage superficial water storage, essential to sustain and stabilize water supply, food and energy production, reduce hydro-climatological hazards, and adapt to climate change, are discussed as well.

More generally, the session presents integrated models for assessment and optimization which identify co-benefits and trade-offs between different Sustainable Development Goals at several spatial and temporal scales: global, regional and basin; and short, middle and long- term perspectives, respectively. Contributions integrate the impacts of climate change into long-term planning, dynamic adaptation or simulation models.

The monitoring of river water levels, river discharges, water bodies extent, storage in lakes and reservoirs, flooding 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 are expected to contribute in an increasing way, as they can provide homogeneous and near real time measurements over large areas, from local to basin wide, regional and global.

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 and during the last decades, an increasing amount of research has been undertaken to better exploit the potential of current and future satellite observations. 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 monitoring applications. However, except for a few pioneering studies, the potential of remotely sensed data to enhance water-related modelling and applications has not yet been fully enough explored, and the use of such data for operational decision-making is far from being consolidated. In this scenario, the forthcoming satellite missions dedicated to global water surfaces monitoring will enhance the quality, as well as the spatial and temporal coverage, of remotely sensed data, thus offering new frontiers and opportunities to enhance the understanding of flood dynamics and our capability to map their extents.

We encourage presentations related to flood monitoring, water level, storage and discharge etc through remotely sensed data including:

- Remote sensing data for flood hazard and risk mapping;
- 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 by means of satellite based observations;
- River flows estimation by means of remote sensed observations;
- River and flood dynamics estimation from satellite (especially time lag, flow velocity, etc.)

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. SMAPex) 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 the new SMAP mission (Q1 2015) and in active microwave with Metop/Ascat series (2006-) 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 characterisation of regional and continental scale soil moisture dynamic (e.g., ALMIP2, GSWP3).

We encourage presentations related to soil moisture remote sensing, including:
- Field experiment, theoretical advances in microwave modelling and calibration/validation activities.
- Root zone soil moisture retrieval and soil moisture assimilation in land surface models as well as in Numerical Weather Prediction models.
- 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).
- Application of satellite soil moisture products for improving hydrological applications such as flood prediction, drought monitoring, rainfall estimation.

Invited Speaker: Wolfgang Wagner from Vienna University of Technology with the title "Resolving the Daily Water Cycle over Land with a Geosynchronous C-band Radar Satellite"

Ensuring long-term water sustainability for increasing human populations is a common goal for water resource managers. Measuring evapotranspiration (ET) at watershed or river-reach scales, upland or urban areas is required to estimate how much water can be apportioned for human needs while maintaining healthy vegetation and habitat for wildlife.
Consequently, much research has been devoted to this topic. However although there have been many advances in meteorological equipment and observations, more universal recognition of the impact of climate and land cover changes on evaporation and hydrology, and the increased accessibility of many parts of the world, evaporation from much of the globe remains elusive to quantify. This is particularly true in areas with few meteorological observations, in regions where precipitation is particularly hard to predict such as in arid and semi-arid or mountain environments. ET measurements are often made on local scales, but scaling up has been problematic due to spatial and temporal variability.
There are challenges associated with handling temporal variability over complex agro-climatic regions and in places with strong effects of unpredictable climate oscillations. For instance, crop/plant coefficients vary seasonally, particularly for riparian, upland vegetation, and urban greenery; traditional approaches of ET estimation commonly neglect the heterogeneity of microclimate, density, species, and phenology that have often led to gross overestimates of plant water use.
In this session, we want to focus on quantifying evapotranspiration dynamics in diverse climates and environments as a tool for improving hydrologic assessments and predictions at a catchment scale. Remote sensing products in many cases are the only spatially distributed information available to account for seasonal climate and vegetation variability and are thus extremely valuable data sources for ET estimation on larger scales.
We invite researchers to contribute theoretical and empirical ET model applications for a variety of dryland vegetation associations and other sensitive environments. We welcome studies that estimate ET using both prognostic and diagnostic approaches from process-based models that rely on the integration of precipitation and soil-vegetation dynamics to a more direct estimation of ET using e.g. remote sensing based data streams. Applications in drought-prone forests, rangelands, mountain and urban areas at a range of spatial and temporal scales are encouraged.

Remote sensing techniques are widely used to estimate and monitor the relationship between vegetation dynamics and the water cycle. Measurements of vegetation water content, transpiration and water stress contribute to a better global understanding of the water movement in the soil-plant system, which is critical for the detection and monitoring of droughts and their impact on biomass. With the number of applications and (planned) missions increasing, this session aims to bring researchers together to discuss the current state 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:
• Modelling studies,
• Remote sensing data analyses,
• New hypothesis,
• Enlightening opinions.

Drones (also Unmanned Aerial Vehicles/Systems (UAV/UAS), Remotely Piloted Aircraft Systems) have revolutionised the ability to collect ultra-high spatial resolution spatial data at the scale of millimetres to centimetres. This has allowed a new scale of mapping and process research in the geosciences. Drones and associated sensors can be cost-effective compared with high spatial resolution airborne and satellite data, providing flexibility in deployment. The development curve of miniaturized drone sensors and data processing software / hardware solution has been transformative, but has not perhaps satisfied scientists’ expectations. Many geoscientists are grappling with quality, stability and reliability in the collection and calibration of data from sensors that have over-promised but under-delivered in practice, or are simply not suited to particular applications. Drone hardware and software has provided tools to process the data, but many tools are black-box, and the resulting observations have quality issues that can impact the questions that are being answered by geoscientists in mapping and process studies. This PICO session will share peoples’ knowledge of the issues and limits of sensors and processing workflows, focusing on communicating and sharing solutions for addressing and advancing our understanding of how ultra-high spatial resolution drone data can (and cannot) be collected, calibrated, processed and then used to answer research questions in the geosciences. Specific themes we wish to promote include:
- Work quantifying sensor quality, stability and reliability in the collection of data, with a focus on sharing information around quantifying limits, providing solutions and communicating best (or limits on) use of data,
- Best practice in the calibration of data (particularly spectral and thermal sensors), and relating this to levels of processing/calibration/validation required to answer geoscience questions,
- Collection and processing of LiDAR and photogrammetry Structure from Motion (SfM) data and the use of fine-resolution digital elevation models (DEMs) in the geosciences,
- Limitations and opportunities in using drones for mapping studies in the geosciences,
- Limitations and opportunities in using drones for process studies in the geosciences,
- Related work that focuses on solutions to issues experienced in using drone data in the geosciences.
- Examples of applications that are affected or overcome issues related to sensor quality, calibration and data pre-processing (orthomosaicing, radiometric correction, vignette correction, BRDF correction, conversion of digital numbers to at-surface reflectance).


We are pleased to announce a keynote presentation from Dr Patrice Carbonneau (University of Durham).

The IR (MWIR 3-5micron and LWIR 7-12micron) sensing technologies have reached a significant level of maturity and has become a powerful method of Earth surface sensing.
Thermal sensing is currently used for characterize land surface Temperature (LST) and Land Surface Emissivity (LSE) and many other environmental proxy variables, which part of them can have a further relevance when assimilated into hydrological and climatological models.
The usefulness of IR sensing has been experimented in many environmental applications and also in the spatio-temporal domain for spatial patterns identification.
The session welcomes communications based on the actual of next future IR imagery from broadband to multi/hyperspectral applied to proximal or remote sensing (ECOSTRESS, ASTER, Sentinel3, Landsat etc. and airborne sensors) in the following specific objectives:
- IR instruments solution
- Instrument radiometric calibration procedures
- Algorithms retrieval for Temperature and Emissivity
- Soil properties characterization
- Evapo-Transpiration, water plants stress and drought
- IR targets identification
- Archaeological prospection
- Urban areas and infrastructure investigation
- Geophysical phenomena characterization
- IR synergy with optical imagery

LINKED TO THIS SESSION IS A REMOTE SENSING JOURNAL SPECIAL ISSUE "Proximal and Remote Sensing in the MWIR and LWIR Spectral Range" WITH DEADLINE DECEMBER 2019.

https://www.mdpi.com/journal/remotesensing/special_issues/EGU_TIR

SUBMISSIONS TO THIS SESSION AND TO THE RS JOURNAL SPECIAL ISSUE ARE WELCOME

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. The above 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”.

Precipitation is the main driver for 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 precipitation patterns lead to a continuous increase of the risk associated with precipitation-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 precipitation induced 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 improving 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 precipitation patterns leading to high-impact events.
- Evidence on the relationship between precipitation patterns and socioeconomic impacts.
- Hazard mitigation procedures.
- Communication strategies for increasing public awareness, preparedness, and self-protective response.
- Impact-based forecast and warning systems

This session addresses two sub-topics: the small scale variability of precipitation, and the atmospheric water cycle. It adopts a PICO format which aims at employing the most modern and captivating environment of scientific exchange (i.e., a 2-minute oral presentation, nicknamed "2-minute madness", followed by an interactive poster presentation on dedicated touch-screens, https://egu2019.eu/guidelines/pico_presenter_guidelines.html).

Precipitation variability: from drop scale to lot scale

The understanding of small scale spatio-temporal variability of precipitation from seconds in time and drop scale in space to 5 minutes in time and 1 km in space is essential for larger scale studies, including more and more hydrological applications, 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 the commonly used point measurement devices (rain gauges and disdrometers) and weather radars, which is greater than 10^7! This session will bring together scientists and practitioners that aim at bridging this scale gap and improving the understanding of small scale precipitation variability, both liquid and solid, as well as its consequences at larger scales.
Contributions addressing one or several of the following issues are especially targeted:
- Novel measurement devices, combinations of devices (both in situ and remote sensors), or experimental set ups enabling to grasp small scale precipitation variability;
- Novel modelling or characterization tools of small scale precipitation variability relying on a wide range of approaches (e.g. scaling, (multi-)fractal, statistic, deterministic, numerical modelling);
- Precipitation drop (or particle) size distribution and its small scale variability, including its consequences for rain rate retrieval algorithms for radars and other remote sensors;
- Physical processes leading to the small-scale rainfall variability
- Examples of hydrological applications where small scale precipitation variability input is required.


The atmospheric water cycle: feedbacks, management, land-use and climate change

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. Land-use changes alter, not only, the local water cycle, but through atmospheric water and energy feedbacks also effect the water cycle in remote locations.
This session aims to:
- show applied studies using fundamental characteristics of the atmospheric branch of the hydrologic cycle on different scales. These fundamentals include, but are not limited to, atmospheric circulation, humidity, residence times, recycling ratios, sources and sinks of atmospheric moisture, energy balance and climatic extremes.
- investigate the remote and local atmospheric feedbacks from human interventions such as irrigation and deforestation on the water cycle, precipitation and climate, based on observations and coupled modelling approaches.
- explore the implications of atmospheric feedbacks on the hydrologic cycle for land and water management. Can we favourably alter atmospheric hydrology and precipitation by means of ground based interventions of changing land cover, and thus changing evaporation, albedo and surface roughness?

Over the last decades, a significant body of empirical and theoretical work has revealed the departure of statistical properties of hydrometeorological processes from the classical statistical prototype, as well as the scaling behaviour of their variables in general, and extremes in particular, in either state, space and/or time. This PICO session (i.e., a 2-minute oral presentation, nicknamed "2-minute madness", followed by an interactive poster presentation on dedicated touch-screens) aims at presenting the latest developments on:
- Coupling stochastic approaches with deterministic hydrometeorological predictions, in order to better represent predictive uncertainty;
- Stochastic-dynamic approaches that are more consistent with the hydrometeorological reality than both deterministic and statistical models separately;
- 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;
- Understanding and using parsimonious parametrizations of extremes in risk analysis applications and hazard prediction.
The suggested session description is submitted to the HS division of EGU and is sponsored by the International Commission on Statistical Hydrology of the International Association of Hydrological Sciences (ICSH-IAHS, former STAHY).

Urban hydrological processes are characterised 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 analyse 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 modelling of urban hydrological response:
- Novel techniques for high resolution precipitation measurement in cities and approaches for merging remote sensing data with in situ measurements to obtain representation of urban precipitation fields;
- Novel approaches to hydrological field measurements in cities, including data obtained from citizen observatories;
- Novel approaches to modelling urban catchment properties and hydrological response, from physics-based models, fully and semi-distributed modelling to stochastic and statistical conceptualisation;
- Applications of measured precipitation fields in urban hydrological models to improve prediction of flood response and real-time control of stormwater systems for pollution load reduction;
- rainfall modelling for urban applications, including stochastic rainfall generators.

Development and application of decision support systems to aquifers and underground reservoirs requires reliable and physically based methods to understand main mechanisms and infer key parameters controlling the fate of the underground environment where rocks, liquids, gases and microbes sit in close proximity and interaction. 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. A wide range of innovative methods have recently emerged, from laboratory experiment to field tests, that are capable of quantifying the extent and the interaction between physical, chemical and biological properties of complex structures at different scales, including: (hydro)geophysical methods, innovative sensors or microscopic imaging techniques. In many situations the information conveyed by each measurement may be far from complete so that one is confronted with the problem of fusing data of various nature to achieve the desired level of knowledge. There is the need to understand how data contribute to the reconstruction of the porous medium and the manner in which measurements from different sources can be merged. This problem can be tackled by new stochastic models able to consider processes arising at different scales. This is opening new avenues for the interpretation of observed processes.

The objective of this session is to discuss significant improvement in our understanding of subsurface processes based on innovative methods allowing the quantification of relevant phenomena and their underling mechanisms such as flow, transport, chemically driven or biologically mediated processes in heterogeneous porous and fractured media. In particular, this session is aimed at providing an opportunity for specialists to exchange information and to introduce various existing and novel alternative 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 new experimental protocols, 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 combines presentations on recent developments in understanding, measuring, and modeling subsurface flow and transport. We aim to include solute/vapor transport processes in both the saturated (groundwater) and unsaturated (vadose) zones, as well as across boundaries (coupled surface/ground water systems) at different scales.

The correct quantification of transport processes, which occur at different spatial and temporal scales, is challenging. It strongly influences predicted spreading, dilution and mixing rates. However, dispersion, mixing and chemical reactions are local phenomena that strongly depend on the interplay between large-scale system heterogeneity and smaller-scale processes. Much effort has been placed in the fundamental understanding of these processes since they are of practical relevance to identify the fate of contaminants in surface and subsurface water that can affect human health and the environment.

The aim of this session is to discuss the effect of flow heterogeneity on transport at different scales, from pore scale up to catchment scale - including theory, modeling, laboratory and field experiments as well as applications. Our contributions deal with the questions: Is macrodispersivity a meaningful parameter? Under which conditions does spatially variable flow enhance mixing and chemical reactions? What is the role played by diffusive processes in modeling transport in porous media? How to upscale dispersion and reactive transport from pore to field-scale? What is the relation between ADE models and dynamic structures of catchment hydrology like travel time distributions? What are appropriate methods to characterize the relevant properties? What are the recent improvements in transport measurement technologies?

The session is co-sponsored by the Groundwater Commission of IAHS.

Particles (inorganic particles, biocolloids, plastics) in environmental systems are of great concern because of their potential adverse effects on ecosystem functions, wildlife and human health. They may also alter the transport properties of dissolved contaminants and change the hydraulic properties of subsurface systems. On the other hand, engineered particles and biocolloids play an important role in site remediation and aquifer restoration.
This interdisciplinary session fosters the exchange among scientists from hydrogeology, microbiology, ecotoxicology, engineering, and analytical chemistry in order to provide a general picture of the occurrence and fate of natural and engineered particles in aquatic and terrestrial systems.
We are expecting contributions in the following fields:
• occurrence, fate and transport of biocolloids, nanoparticles and other particles (microplastics, soot, ...) in aquatic and terrestrial systems
• methods to detect, characterize, and quantify particles in aquatic and terrestrial systems
• advanced experimental methods to test the behaviour of particles in aquatic and terrestrial systems (mesocosms, non-invasive imaging, ...)
• interactions between biocolloids, particles and solid surfaces
• biocolloid biodegradation in the presence of solids
• toxicity of products generated from biological disruption of pollutants in the presence of biocolloids
• adverse effects of nanoparticles on microorganisms
• effects of climate change on biocolloid and nanoparticle migration
• public health risks associated with water and air polluted with biocolloids and nanoparticles

Dissolution, precipitation and chemical reactions between infiltrating fluid and rock matrix alter the composition and structure of the rock, either creating or destroying flow paths. Strong, nonlinear couplings between the chemical reactions at mineral surfaces and fluid motion in the pores often leads to the formation of intricate patterns: networks of caves and sinkholes in karst area, wormholes induced by the acidization of petroleum wells, porous channels created during the ascent of magma through peridotite rocks. Dissolution and precipitation processes are also relevant in many industrial applications: dissolution of carbonate rocks by CO2-saturated water can reduce the efficiency of CO2 sequestration, mineral scaling reduces the effectiveness of heat extraction from thermal reservoirs, acid rain degrades carbonate-stone monuments and building materials.

With the advent of modern experimental techniques, these processes can now be studied at the microscale, with a direct visualization of the evolving pore geometry. On the other hand, the increase of computational power and algorithmic improvements now make it possible to simulate laboratory-scale flows while still resolving the flow and transport processes at the pore-scale.

We invite contributions that seek a deeper understanding of reactive flow processes through interdisciplinary work combining experiments or field observations with theoretical or computational modeling. We seek submissions covering a wide range of spatial and temporal scales: from table-top experiments and pore-scale numerical models to the hydrological and geomorphological modelling at the field scale. We also invite contributions from related fields, including the processes involving coupling of the flow with phase transitions (evaporation, sublimation, melting and solidification).

In catchment hydrology, subsurface flow is a well-recognized process but is still challenging to capture. Different terms exist to characterize subsurface flow, such as shallow subsurface runoff, interflow, subsurface stormflow, lateral flow or soil water flow. This reflects the different underlying concepts derived from various experimental and modeling studies in different environmental settings and for different spatial and temporal scales. Subsurface flow is responsible for the transport of nutrients and pollutants from the terrestrial to the aquatic ecosystems, which underlines its importance for the adjacent surface water bodies in terms of both water quantity and quality. This makes an accurate process understanding of subsurface flow essential.
Significant knowledge has been gained from experimental studies at the point and hillslope scales. These studies have identified controlling factors for subsurface flow (e.g., initial soil moisture, preferential flow paths, drainable porosity, precipitation inputs, soil properties, bedrock topography or stratification of soils). However, the importance at the catchment scale, and how these findings can be implemented in catchment scale rainfall-runoff models, remain poorly understood. This is mostly due to the nonlinearity of subsurface flow and due to a lack of knowledge in understanding where subsurface flow is generated within a catchment and when. Furthermore, simulation of subsurface runoff in catchment rainfall-runoff models is frequently based on calibration and validation for single rainfall-runoff events. However, such often isolated events, assuming steady state conditions are not sufficient to capture the whole range of initial conditions and especially the thresholds for generating subsurface runoff. Thus, continuously measured proxies to assess the accuracy of the simulated subsurface runoff are needed. New in-situ high-frequency measurements of tracers can help to bridge the gap between hillslope and point scale measurements and simulated catchment scale responses and thus improve the accuracy of these models.
This session aims to address the current state of the art for measurement, assessment and modeling of subsurface runoff processes. We welcome experimental and modeling studies on the following topics: (i) (Non-)Invasive methods for the investigation and monitoring of subsurface flow in space and time and its connection to the stream network; (ii) linking spatial patterns of subsurface flow with soil and lithological heterogeneity, including stratification of soils; (iii) assessment of the role of subsurface runoff for catchment response; and (iv) validation approaches to assess the accuracy of the simulated subsurface runoff using biogeochemical proxies (e.g. stable isotopes, dissolved silica, nitrate, dissolved organic carbon, trace elements etc).

This session deals with the use of geophysical methods for the characterisation of subsurface properties, states, and processes in contexts such as hydrology, agriculture, contaminant transport, etc. Geophysical methods potentially provide subsurface data with an unprecedented spatial and a high temporal resolution in a non-invasive manner. However, the interpretation of these measurements is far from straightforward in many contexts and various challenges still remain. Amongst these, the need for improved quantitative use of geophysical measurements in model conceptualisation and parameterisation, and the need to move quantitative hydrogeophysical investigations beyond the column and field scale towards the catchment scale. Therefore, we especially encourage submissions addressing advances in i) the acquisition, inversion and interpretation of geophysical data and other minimally invasive methods in a (contaminant) hydrological context, ii) model-data fusion including new concepts for joint and coupled inversion, and iii) petrophysical understanding linking hydrological and geophysical properties.

Groundwater is world's most important, best protected and most exploited freshwater resource. It is intensively used by man; it is the prime source for drinking water supply and irrigation, hence critical to the global water-food-energy security nexus. But also for sustaining low flow requirements and ecological values of groundwater dependent ecosystems, the contribution by groundwater flow is essential. Groundwater therefore needs to be managed wisely, protected and especially sustainably used. These requirements are also expressed in Integrated Water Resources Management concepts, as e.g. in the European Water Framework Directive. Under a changing environment, climate, land use, population growth, etc., this task becomes a challenge especially in the light of limited data availability and consequential uncertainties. From arid over humid to arctic regions, in every type of climate changing environmental conditions become apparent and have very different local to regional hydrological effects.
In this session, we invite contributions which identify new consequences of a changing environment for future management, protection, and sustainable use of groundwater by applying integrative modelling, including water quantity and quality investigations as well as field observational studies. Methodologies, strategies, case studies and quantitative techniques for dealing with uncertainty or limited data availability are particularly welcome. We encourage studies describing how groundwater resources benefit from an Integrated Water Resources Management approaches. Furthermore, contributions describing case studies and innovative techniques for adaptive management and protection of groundwater resources such as artificial recharge and conjunctive use are desired.