Union-wide
Inter- and Transdisciplinary Sessions
Disciplinary sessions AS–GM
Disciplinary sessions GMPV–TS

Session programme

HS

HS – Hydrological Sciences

Programme group chair: Maria-Helena Ramos

MAL14a
HS 2020/2021 Henry Darcy Medal lectures & 2020 Arne Richter Award for Outstanding ECS Lecture
Convener: Maria-Helena Ramos
Presentations
| Tue, 20 Apr, 15:00–17:00 (CEST)
MAL14b
HS 2020/2021 John Dalton Medal Lectures & 2021 Division Outstanding ECS Award Lecture
Convener: Maria-Helena Ramos
Presentations
| Thu, 22 Apr, 15:00–17:00 (CEST)
MAL1d
EGU 2020/2021 Alexander von Humboldt Medal Lectures
Conveners: Alberto Montanari, Helen Glaves
Presentations
| Fri, 23 Apr, 11:30–12:30 (CEST), 13:30–14:30 (CEST)
MAL1b
EGU 2020/2021 Alfred Wegener Medal Lectures
Conveners: Alberto Montanari, Helen Glaves
Presentations
| Wed, 21 Apr, 11:30–14:30 (CEST)
DM13
Division meeting for Hydrological Sciences (HS)
Convener: Maria-Helena Ramos
Thu, 22 Apr, 11:30–12:30 (CEST)
PGM2

Annual meeting of the HS9 subdivision for Erosion, Sedimentation and River Processes.

Convener: Stefan Haun
Mon, 26 Apr, 17:30–18:15 (CEST)
PGM3

Meeting of the subdivision HS10 Ecohydrology, wetlands and estuaries. Exchange on the organization of the EGU General Assembly and general activities of the subdivision. Everybody interested is kindly invited.

Convener: Anke Hildebrandt
Thu, 29 Apr, 18:00–18:45 (CEST)
NET16
HS & GI ECS-networking event
Conveners: Caitlyn Hall, Tim van Emmerik | Co-conveners: Sina Khatami, Elena Cristiano
Mon, 26 Apr, 12:30–13:30 (CEST)

HS1 – General Hydrology

Programme group scientific officers: Elena Toth, Maria-Helena Ramos

HS1.1 – Innovative sensors and monitoring in hydrology

Programme group scientific officers: Elena Toth, Maria-Helena Ramos

HS1.1.1 EDI

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

Connected a sensor for iPhone to an Arduino or Raspberri Pi? 3D printed an automated water quality sampler? Or build a Cloud Storage system from Open Source Components? Show it!

New methods in hydrology, plant physiology, seismology, remote sensing, ecology, etc. are all welcome. Bring prototypes and demonstrations to make this the most exciting Poster Only (!) session of the General Assembly.

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

Co-organized by BG2
Convener: Rolf Hut | Co-conveners: Theresa Blume, Marvin ReichECSECS, Andy Wickert
vPICO presentations
| Mon, 26 Apr, 15:30–17:00 (CEST)
HS1.1.2

Water is our planet’s most vital resource, and the primary agent in some of the biggest hazards facing society and nature. The twin pressures of population growth and a rapidly changing global climate act as multipliers of water’s value and of water-related hazards.

River streamflow is one of the most crucial hydrological variables for ecology, for people and industry, for flood risk management and for understanding long term changes to the hydrological regime. However, despite significant efforts, long-term, spatially dense monitoring networks remain scarce, and even the best monitoring networks can fail to perform when faced with extreme conditions, and lack the precision and spatial coverage to fully represent crucial aspects of the hydrological cycle.

Happily, a number of new technologies and techniques are emerging which show great potential to meet these challenges. In this context, this session focuses on:
1) Innovative methodologies for measuring/modelling/estimating river stream flows;
2) Real-time acquisition of hydrological variables;
3) Remote sensing for hydrological & morphological monitoring;
4) Measuring extreme conditions associated with a changing climate;
5) Measurement of sudden-onset extreme flows associated with catastrophic events;
6) Strategies to quantify and describe hydro-morphological evolution of rivers;
7) New methods to cope with data-scarce environments;
8) Inter-comparison of innovative & classical models and approaches;
9) Evolution and refinement of existing methods;
10) Guidelines and standards for hydro-morphological streamflow monitoring;
11) Quantification of uncertainties;
12) Development of expert networks to advance methods.

Contributions are welcome with an emphasis on innovation, efficiency, operator safety, and meeting the growing challenges associated with the changing climate, and with natural and anthropogenically driven disasters such as dam failures and flash floods.

Additionally, presentations will be welcomed which explore options for greater collaboration in advancing riverflow methods and which link innovative research to operational monitoring.

This session is sponsored by the COST Action CA16219, Harmonisation of UAS techniques for agricultural and natural ecosystems monitoring (HARMONIOUS).

Co-organized by GI4/GM2/NH1
Convener: Nick Everard | Co-conveners: Silvano F. Dal Sasso, Alexandre Hauet, Alonso PizarroECSECS
vPICO presentations
| Tue, 27 Apr, 11:00–12:30 (CEST)
HS1.1.5 EDI

Within the water cycle, physical and chemical interactions between water, air and land shape the Earth’s surface. Human activity also induces major changes to natural systems at a wide range of temporal and spatial scales. Experimental methods have played – and still play – a fundamental role in Hydrology and Hydraulics. Laboratory- and field-based experiments allow physical systems to be analysed under semi-controlled conditions to understand process-form interactions. As such, experimental studies provide an effective platform for investigating physical processes under controlled hydrometeorological or physical conditions, and improve understanding of the Earth systems.

This session aims to provide with a discussion platform to exchange experiences on the design, methodologies and application of physical experiments in hydrology and hydraulics, both in the laboratory and the field. We welcome experimental research contributions across a series of disciplines with a hydrological, hydraulic and geomorphological focus across a wide range of spatiotemporal scales.

We invite contributions directing on (but not restricted to):
- The use of laboratory- and field-based experiments to understand real-world physical systems with a hydrological, geomorphological or hydraulic focus;
- Fundamental science and practical applications of physical and experimental models such as flumes, lysimeters, soil columns, rainfall simulators or scaled physical systems;
- The application of novel and innovative instrumentation, measurement and visualisation techniques;
- Experimental adaptations to well-established monitoring or data analysis techniques;
- Development and application of hybrid or composite (numerical-physical) models to contribute to numerical modelling frameworks;
- The use of experimental methods and models for science communication and as demonstrative teaching tools.

Convener: Jorge Isidoro | Co-conveners: Adriana Bruggeman, Marinos EliadesECSECS, Carla FerreiraECSECS, Daniel Green, Christoph Külls
vPICO presentations
| Fri, 30 Apr, 13:30–15:00 (CEST)
CR2.4 EDI

Geophysical and in-situ measurements of the cryosphere offer important baseline datasets, as well as validation for modelling and remote sensing products. In this session we welcome contributions related to a wide spectrum of methods, including, but not limited to radioglaciology, active and passive seismology, acoustic sounding, Global Navigation Satellite System (GNSS) reflectometry or time delay techniques, cosmic ray neutron sensing, remotely operated vehicle (ROV) or drone applications, geoelectrics, nuclear magnetic resonance (NMR) and methods in radiative transfer (i.e. infrared photography, thermal sounding...).

Contributions could be related to field applications, new approaches in geophysical or in-situ survey techniques, or theoretical advances in data analysis processing or inversion. Case studies from all parts of the cryosphere such as snow and firn, alpine glaciers, ice sheets, glacial and periglacial environments, permafrost, or 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 year our session will be a virtual PICO session. The session begins with each presenter giving a “quick fire” 2-minute overview of their research, followed by breakout "rooms" - one per presentation, for authors to further discuss their research. We hope the virtual PICO format will provide as much lively discussion as our normal in-person PICO!

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

Amy R. Macfarlane: Quasi in-situ snow and sea ice interface microstructure measured by micro-computed tomography

Public information:
IMPORTANT: THIS SESSION WILL NOW TAKE PLACE 1 HOUR LATER 16:30–18:00 CEST!

zoom link for this session
https://us02web.zoom.us/j/87446467757?pwd=K1FUYVpmaDlhSW4rdEhhR0NIL2UrUT09
Co-organized by GI4/HS1.1/SM2
Convener: Franziska KochECSECS | Co-conveners: Polona Itkin, Kristina Keating, Mariusz Majdanski, Artur Marciniak, Emma C. SmithECSECS
vPICO presentations
| Mon, 26 Apr, 15:30–17:00 (CEST)
GM2.11 EDI

Recent advances in image collection, e.g. using uncrewed aerial vehicles (UAVs), and topographic measurements, e.g. using terrestrial or airborne LiDAR, are providing an unprecedented insight into landscape and process characterization in geosciences. In parallel, historical data including terrestrial, aerial, and satellite photos as well as historical digital elevation models (DEMs), can extend high-resolution time series and offer exciting potential to distinguish anthropogenic from natural causes of environmental change and to reconstruct the long-term evolution of the surface from local to landscape scale.

For both historic and contemporary scenarios, the rise of techniques with ‘structure from motion’ (SfM) processing has democratized data access and offers a new measurement paradigm to geoscientists. Photogrammetric and remote sensing data are now available on spatial scales from millimetres to kilometres and over durations of single events to lasting time series (e.g. from sub-second to decadal-duration time-lapse), allowing the evaluation of event magnitude and frequency interrelationships.

The session welcomes contributions from a broad range of geoscience disciplines such as geomorphology, cryosphere, volcanology, hydrology, bio-geosciences, and geology, addressing methodological and applied studies. Our goal is to create a diversified and interdisciplinary session to explore the potential, limitations, and challenges of topographic datasets for the reconstruction and interpretation of past and present 2D and 3D changes in different environments and processes. We further encourage contributions describing workflows that optimize data acquisition and processing to guarantee acceptable accuracies and to automate data application (e.g. geomorphic feature detection and tracking), and field-based experimental studies using novel multi-instrument and multi-scale methodologies. This session invites contributions on the state of the art and the latest developments in i) modern photogrammetric and topographic measurements, ii) remote sensing techniques as well as applications, iii) modelling technologies, and iv) data processing tools, for instance, using machine learning approaches.

Co-organized by GI1/HS1.1/NH6/SSS11
Convener: Livia PiermatteiECSECS | Co-conveners: Anette EltnerECSECS, Penelope HowECSECS, Mike James, Mark Smith
vPICO presentations
| Wed, 28 Apr, 16:15–17:00 (CEST)

HS1.2 – Cross-cutting hydrological sessions

Programme group scientific officers: Elena Toth, Maria-Helena Ramos

HS1.2.1 EDI

Liaising with stakeholders, policy-makers and society is becoming increasingly important for academic research to turn research into impactful action, but also to improve research by allowing society to take part within research processes in terms of co-producing knowledge and policy. 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.
Contributions focus on:
1. Science-policy interface in hydrology. 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? How do we deal with uncertainty, adaptation, path dependencies but also with aspects of power, inequality and vested interests in the co-production of knowledge and policy?
2. Interdisciplinary collaborations. How do we create the interdisciplinary knowledge needed to address the questions faced by decision-makers and societal stakeholders? How have new, interdisciplinary, science questions been generated in response to existing and emerging research problems? How can individual disciplinary perspectives come together in interdisciplinary studies and experiments?
3. Hydrology as practiced within society. Who are the users of our knowledge, how useful is our knowledge for those societal users, how useful are our tools, models and methods? What approaches are available to support a fruitful collaboration between hydrological science and practitioners? And, since scientists are not removed from the things they study, how has hydrological science been shaped by the historical interplay of cultural, political and economic factors? What are the opportunities and challenges that this science/society nexus creates for producing scientific knowledge?

Co-organized by EOS6
Convener: Maria-Helena Ramos | Co-conveners: Gemma Carr, Sharlene L. GomesECSECS, Britta HöllermannECSECS, Thomas ThalerECSECS, Jutta Thielen-del Pozo, Elena Toth, Micha Werner
vPICO presentations
| Mon, 26 Apr, 13:30–15:00 (CEST)
HS1.2.4 EDI

The International Association of Hydrological Sciences (IAHS) coordinates two initiatives in hydrology:

- The Panta Rhei hydrological decade 2013- 2022, focusing on gains in our understanding of water cycle processes, their changing dynamics in respect of interactions and feedbacks with human systems. [1]
- The 23 Unsolved Problems in Hydrology (UPH), launched in 2017 after a public consultation process, in collaboration with the Hydrology Divisions of EGU and AGU as well as the IAH. [2]

This session presents works related to these initiatives.

Approaching the end of this Panta Rhei decade (2013-2022), it is time to synthesize the achievements of this decade. The main focus of this grand synthesis, which will be published in an IAHS book, is on coevolution and prediction of coupled human-water systems, including understanding of emergent phenomena, mechanisms, and implications for predictions and practices. Focus is put on theoretical/conceptual framework for understanding changes in hydrology and society; coevolution and emergent phenomena; dynamic models; data needs and acquisition; benchmark datasets in various context and scales, including human-flood, human-drought, agricultural, transboundary and global systems. Case studies from Panta Rhei working groups, IAHS Commissions and beyond are also welcome.

The 23 UPH are articulated around 7 themes: Time variability and change, Space variability and scaling, Variability of extremes, Interfaces in hydrology, Measurements and data, Modelling methods, and Interfaces with society. A crucial issue is to put together fragmented knowledge to address the questions raised and enhance coherence in hydrological sciences. The purpose of this session is to present research results that advance the understanding of any of the 23 UPH, review (or present a contribution to review) the state of the art of one (or more) of the UPH, pointing towards directions where progress is most promising.

[1] Panta-Rhei: https://iahs.info/Commissions--W-Groups/Working-Groups/Panta-Rhei.do
[2] 23 UPH: https://doi.org/10.1080/02626667.2019.1620507

Co-sponsored by IAHS
Convener: Fuqiang Tian | Co-conveners: Berit Arheimer, Günter Blöschl, Christophe Cudennec, Giuliano Di Baldassarre, Heidi Kreibich, Elena Toth, Jing WeiECSECS
vPICO presentations
| Mon, 26 Apr, 11:00–12:30 (CEST)
HS1.2.6

Understanding the complex interactions of the coupled terrestrial-atmospheric water cycle requires cross-compartment strategies encompassing coupled modeling from the bedrock to the top of the atmosphere, integrated hydro-meteorological observations and datasets, novel data assimilation schemes and multivariable validation approaches. The objective of the session is to create opportunities for interdisciplinary exchange of ideas and experiences among members of the Earth System and hydrology communities. Contributions are invited dealing with the complex interactions between groundwater, surface water, land surface and atmospheric processes with a specific focus on the development, application and validation of novel one-way (both deterministic and ensemble) or fully-coupled hydrometeorological modeling systems for process understanding and predictions and projections across various space- and time scales. This includes also combined dynamical-statistical approaches and studies addressing data assimilation in coupled models. An additional focus is placed on the use of field experiments and testbeds equipped with complex sensors and measurement systems allowing cross-compartment and multivariable validation of these modeling systems.

Co-organized by AS5
Convener: Harald Kunstmann | Co-conveners: Gabriëlle De Lannoy, Martin Drews, Harrie-Jan Hendricks Franssen, Stefan Kollet, Insa Neuweiler, Alfonso Senatore
vPICO presentations
| Fri, 30 Apr, 15:30–17:00 (CEST)
HS1.2.7 EDI

This session focuses on advances in theoretical, methodological and applied studies in hydrologic and broader earth system dynamics, regimes, transitions and extremes, along with their physical understanding, predictability and uncertainty, across multiple spatiotemporal scales.

The session further encourages discussion on interdisciplinary physical and data-based approaches to system dynamics in hydrology and broader geosciences, ranging from novel advances in stochastic, computational, information-theoretic and dynamical system analysis, to cross-cutting emerging pathways in information physics.

Contributions are gathered from a diverse community in hydrology and the broader geosciences, working with diverse approaches ranging from dynamical modelling to data mining, machine learning and analysis with physical process understanding in mind.

The session further encompasses practical aspects of working with system analytics and information theoretic approaches for model evaluation and uncertainty analysis, causal inference and process networks, hydrological and geophysical automated learning and prediction.

The operational scope ranges from the discussion of mathematical foundations to development and deployment of practical applications to real-world spatially distributed problems.

The methodological scope encompasses both inverse (data-based) information-theoretic and machine learning discovery tools to first-principled (process-based) forward modelling perspectives and their interconnections across the interdisciplinary mathematics and physics of information in the geosciences.

Take part in a thrilling session exploring and discussing promising avenues in system dynamics and information discovery, quantification, modelling and interpretation, where methodological ingenuity and natural process understanding come together to shed light onto fundamental theoretical aspects to build innovative methodologies to tackle real-world challenges facing our planet.

We are glad to welcome Mahesh Maskey (dynamical systems) and Uwe Ehret (information theory) as our invited authors for this eclectic session, where we promote a fruitful cross-fertilisation between complementary visions of the world.

Public information:
This session focuses on advances in theoretical, methodological and applied studies in hydrologic and broader earth system dynamics, regimes, transitions and extremes, along with their physical understanding, predictability and uncertainty, across multiple spatiotemporal scales.

The session further encourages discussion on interdisciplinary physical and data-based approaches to system dynamics in hydrology and broader geosciences, ranging from novel advances in stochastic, computational, information-theoretic and dynamical system analysis, to cross-cutting emerging pathways in information physics.

Contributions are gathered from a diverse community in hydrology and the broader geosciences, working with diverse approaches ranging from dynamical modelling to data mining, machine learning and analysis with physical process understanding in mind.

The session further encompasses practical aspects of working with system analytics and information theoretic approaches for model evaluation and uncertainty analysis, causal inference and process networks, hydrological and geophysical automated learning and prediction.

The operational scope ranges from the discussion of mathematical foundations to development and deployment of practical applications to real-world spatially distributed problems.

The methodological scope encompasses both inverse (data-based) information-theoretic and machine learning discovery tools to first-principled (process-based) forward modelling perspectives and their interconnections across the interdisciplinary mathematics and physics of information in the geosciences.

Take part in a thrilling session exploring and discussing promising avenues in system dynamics and information discovery, quantification, modelling and interpretation, where methodological ingenuity and natural process understanding come together to shed light onto fundamental theoretical aspects to build innovative methodologies to tackle real-world challenges facing our planet.

We are glad to welcome Mahesh Maskey (dynamical systems) and Uwe Ehret (information theory) as our invited authors for this eclectic session, where we promote a fruitful cross-fertilisation between complementary visions of the world.
Co-organized by NP5
Convener: Rui A. P. Perdigão | Co-conveners: Julia HallECSECS, Cristina Prieto, Maria KireevaECSECS, Shaun HarriganECSECS, Grey Nearing, Benjamin L. Ruddell, Steven Weijs
vPICO presentations
| Thu, 29 Apr, 15:30–17:00 (CEST)
EOS5.3 EDI

In recent years, the geoscience community has been making strides towards making our science more open, inclusive, and accessible, driven both by individual- or community-led initiatives and by broader-scale regulatory changes. Open-source software, accessible codebases and open online collaboration resources (such as GitHub, VHub, etc.) are becoming the norm in many disciplines. The open-access publishing landscape has been changing too: several geoscience journals have defined data availability policies, and many publishers have introduced green and gold open-access options to their journal collections. Pre-print servers and grassroots diamond open-access journals are changing the readiness with which scholarly content can be accessed beyond the traditional paywall model.

However, good scientific practice requires research results to be reproducible, experiments to be repeatable and methods to be reusable. This can be a challenge in geosciences, with available data sets that are becoming more complex and constantly superseded by new, improved releases. Similarly, new models and computational tools keep emerging in different versions and programming languages, with a large variability in the quality of the documentation. Moreover, how data and models are linked together towards scientific output is very rarely documented in a reproducible way. As a result, very few published results are reproducible for the general reader. These challenges especially apply to hydrology, which is highlighted here as an example in the general geosciences.

This session is designed to gain a community overview of the current open-science landscape and how this is expected to evolve in the future. It aims to foster a debate on open science, lower the bar for engaging in open science and showcase examples, including software and other instruments for assisting open research. This may include software and tools, open science dissemination platforms (such as pre-print servers and journals), the teams driving the development of open-science resources and practices, and discussion on the regulatory moves towards standardising open access in the scientific community and what those policies mean in practice. The session has a focus on hydrological sciences, as an example within the geosciences. This session should advance the discussion on open and reproducible science, highlight its advantages and also provide the means to bring this into practice.

Co-organized by HS1.2
Convener: Remko C. Nijzink | Co-conveners: Niels Drost, James Farquharson, Alexandra KushnirECSECS, Francesca Pianosi, Stan Schymanski, Leonardo UiedaECSECS, Fabian WadsworthECSECS
vPICO presentations
| Tue, 27 Apr, 15:30–17:00 (CEST)

HS2 – Catchment hydrology

Programme group scientific officers: Kerstin Stahl, Alberto Viglione

HS2.1 – Catchment hydrology in diverse climates and environments

Programme group scientific officers: Kerstin Stahl, Alberto Viglione

HS2.1.1 EDI

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

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

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

Convener: Lionel Jarlan | Co-conveners: Said Khabba, María José Polo, Yves Tramblay, Mehrez Zribi
vPICO presentations
| Fri, 30 Apr, 13:30–15:00 (CEST)
HS2.1.2

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

Convener: Fiachra O'Loughlin | Co-conveners: Peter Burek, Feyera Hirpa
vPICO presentations
| Thu, 29 Apr, 13:30–14:15 (CEST)
HS2.1.3

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

Co-organized by BG4
Convener: E. Sauquet | Co-conveners: Anna Maria De Girolamo, Catherine Sefton
vPICO presentations
| Thu, 29 Apr, 11:45–12:30 (CEST)
HS2.1.4

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

Convener: Jun Niu | Co-conveners: Noel Aloysius, Bellie Sivakumar
vPICO presentations
| Mon, 26 Apr, 09:00–10:30 (CEST)
HS2.1.5 EDI

Forests are recognized as prime regulators of the hydrological cycle. Their change has effects on the ecosystem services they provide via their water and biochemical cycles. The traditional idea that forest hydrology emphasizes the role of forests and forest management practices on runoff generation and water quality has been broadened in the light of rapid global change. Some of the largest pristine forested areas are in the tropics and have suffered drastic land-use changes during recent decades. These tropical systems are still markedly underrepresented in hydrological studies compared to temperate regions, especially concerning long-term experimental setups and monitoring networks.
Anthropogenic intervention is exerting enormous pressure on natural ecosystems, affecting water quantity and quality, and, consequently, threatening socio-economic and human development as described by the UN Sustainable Development Goals. Yet, we lack a proper understanding of how catchments respond to changing environmental conditions and disturbances. To answer these open questions, it requires interdisciplinary approaches in combination with novel monitoring methods and modelling efforts. This session brings together studies that will enhance our understanding and stimulate discussions on the impact of global change on hydrological processes in forest systems at different scales.
We invite field experimentalists and modelers to submit contributions that investigate hydrological processes in forests from boreal to tropical regions, including water quality, the carbon cycle, or ecohydrological aspects.
This session welcomes studies that:
1) Improves our understanding of forested hydrological processes using an experimental or modelling approach or a combination of both;
2) Assesses the hydrological-related impacts of land use/cover change in forested systems;
3) Presents new methods (e.g. remote sensing techniques) or tools that unveils new perspectives or data sources in forest hydrology;
4) Includes interdisciplinary research that supports the consideration of overlooked soil-plant-atmosphere components in hydrological studies.

Convener: Alicia CorreaECSECS | Co-conveners: Christian Birkel, Luisa Hopp, Rodolfo Nóbrega, Daniele Penna
vPICO presentations
| Thu, 29 Apr, 14:15–15:00 (CEST)
HS2.1.6 EDI

Despite only representing about 25% of continental land, mountains are an essential part of the global ecosystem and are recognised to be the source of much of the world’s surfaces water supply apart from important sources of other commodities like energy, minerals, forest, and agricultural products, and recreation areas. In addition, mountains represent a storehouse for biodiversity and ecosystem services. People residing within mountains or in their foothills represent approximately 26% of the world’s population, and this percentage increases to nearly 40% when considering those who live within watersheds of rivers originated in a mountain range. This makes mountains particularly sensitive to climate variability, but also unique areas for identifying and monitoring the effects of global change thanks to the rapid dynamics of their physical and biological systems.
This session aims to bring together the scientific community doing hydrology research on mountain ranges across the globe to share results and experiences. Therefore, this session invites contributions addressing past, present, and future changes in mountain hydrology due to changes in either climate and/or land use, how these changes affect local and downstream territories, and adaptation strategies to ensure the long-term sustainability of mountain ecosystem services, with a special focus on water cycle regulation and water resources generation. Example topics of interest for this session are:
• Sources of information for evaluating past and present conditions (in either surface and/or groundwater systems).
• Methods for differentiating climatic and anthropogenic drivers of hydrological change.
• Modelling approaches to assess hydrological change.
• Evolution, forecasting, and impacts of extreme events.
• Case studies on adaptation to changing water resources availability.

Convener: David Haro MonteagudoECSECS | Co-conveners: Santiago Beguería, Andrea Momblanch
vPICO presentations
| Wed, 28 Apr, 15:30–17:00 (CEST)
HS2.1.7 EDI

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

Co-organized by CR7
Convener: Guillaume Thirel | Co-conveners: Francesco Avanzi, Doris DuethmannECSECS, Abror Gafurov, Juraj Parajka
vPICO presentations
| Thu, 29 Apr, 09:00–11:45 (CEST)
CR5.1 EDI

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.

Co-organized by CL4/HS2.1
Convener: Nora Helbig | Co-conveners: Neige Calonne, Richard L.H. Essery, Henning Löwe, Vincent Vionnet
vPICO presentations
| Wed, 28 Apr, 13:30–17:00 (CEST)

HS2.2 – From observations to concepts to models (in catchment hydrology)

Programme group scientific officers: Kerstin Stahl, Alberto Viglione

HS2.2.1

Understanding and representing hydrological processes is the basis for developing and improving hydrological and Earth system models. Modeling and learning is a symbiotic and continuous process through which our understanding of human-natural systems is formulated and tested constantly. As a result, a variety of models are developed and trained by quantitative and qualitative data across desired temporal and spatial scales.
In this session, we welcome contributions on the development of novel data sets and frameworks for model development and evaluation across spatio-temporal scales from catchment to continental scale hydrology. The vision of our session, following the initiative of 23 Unsolved Problems in Hydrology (UPH, https://doi.org/10.1080/02626667.2019.1620507), is to address three questions: What are the hydrologic laws at the catchment scale and how do they change with scale? How can hydrological models be adapted to be able to extrapolate to changing conditions, including changing vegetation dynamics? How can we disentangle and reduce model structural/parameter/input uncertainty in hydrological prediction?

We welcome contributions that (but not limited to):
(1) introduce new global and regional data products into the modeling process;
(2) introduce new approaches for model calibration and evaluation, especially to improve process representation, and/or to improve model predictions under changing conditions;
(3) improve model structure by representing often neglected processes in hydrological models such as human impacts, river regulations, irrigation, as well as vegetation dynamics;
(4) provide novel concepts for improving the characterization of internal and external model fluxes and their spatio-temporal dynamics;
(5) upscale experimentalists' knowledge from smaller to larger scale by identifying driving forces for spatial patterns for a better usage of them in models;
(6) suggest more effective monitoring and seamless modeling of spatial patterns in hydrology and land models using distributed earth observations;
(7) develop novel approaches and performance metrics for evaluating and constraining models in space and time; and
(8) identify model limitations and conceptual improvements that are of general relevance to the geosciences modeling community.

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

Convener: Sina Khatami | Co-conveners: Luis Samaniego, Simon Stisen, Shervan GharariECSECS, Björn Guse
vPICO presentations
| Wed, 28 Apr, 13:30–15:00 (CEST)
HS2.2.2

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.

Convener: Christine Stumpp | Co-conveners: Michael Rinderer, Michael Stockinger, Markus Weiler
vPICO presentations
| Fri, 30 Apr, 15:30–17:00 (CEST)
HS2.2.4 EDI

Salinisation of both groundwater and surface water resources is a growing problem, threatening freshwater security for agricultural, domestic and industrial purposes, as well as biodiversity, in many regions of the world. Although the problem of freshwater salinisation is increasingly recognised, there are major research gaps in terms of its impacts, extent and magnitude, particularly at cross-regional to global scales. Both observational, remote sensing and model-driven approaches are needed to improve our understanding of salinisation processes, drivers and impacts across different scales, and to ensure sustainable water resources management today and in the future.

This session aims to bring together scientists working on salinity monitoring (in-situ or remote sensing) data, as well as model-driven studies related to quantifying and predicting historic to future salinisation patterns, drivers and impacts at catchment to global scales. Contributions including - but not limited to - any of the following topics are of particular interest for this session:

- Surface water and groundwater interactions and its effects on salinity dynamics
- Impacts of hydrological extremes and seasonality on salinity levels of freshwater resources
- Human and hydro-climatic drivers of freshwater salinisation across different spatial and temporal scales
- Implications of inland salinity for ecosystem health and sectoral water use
- Applications of surface and/or groundwater in-situ and remote sensing data, and/or data-driven models to determine salinity concentrations across multiple scales
- Global change (e.g. climate change, land use change) impacts on future freshwater salinisation
- Assessment of management and adaptation measures to salinity changes

Convener: Josefin ThorslundECSECS | Co-conveners: Martina Flörke, Michelle van Vliet, Sujay Kaushal
vPICO presentations
| Fri, 30 Apr, 13:30–15:00 (CEST)

HS2.3 – Water quality at the catchment scale

Programme group scientific officers: Kerstin Stahl, Alberto Viglione

HS2.3.1 EDI

Land use and climate change as well as legal requirements (e.g. the EU Water Framework Directive) pose challenges for the assessment and sustainable management of surface water quality at the catchment scale. Sources and pathways of nutrients and other pollutants as well as nutrient interactions have to be characterized to understand and manage the impacts 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 and provide assessments of future change and management options. However, insufficient temporal and/or spatial resolution, a short duration of observations and the widespread use of different 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. 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. The strong need for advances in water quality models remains.

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 (nutrients, organic matter, algae, or sediment) at the catchment scale. Contributions are welcome that cover the following issues:

- Experimental and modelling studies on the identification of sources, hot spots, pathways and interactions of nutrients and other, related 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 other pollutants at the catchment scale
- Catchment management: pollution reduction measures, stakeholder involvement, scenario analysis for catchment management

Convener: Paul Wagner | Co-conveners: Nicola Fohrer, Ype van der Velde, Andrew Wade
vPICO presentations
| Fri, 30 Apr, 13:30–17:00 (CEST)
HS2.3.2 EDI

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

Convener: Andreas Musolff | Co-conveners: Benjamin Abbott, Rémi DupasECSECS, Stefanie LutzECSECS, Camille Minaudo
vPICO presentations
| Wed, 28 Apr, 13:30–15:00 (CEST)
HS2.3.3

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

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

Convener: Matthias Gassmann | Co-conveners: Daniele la Cecilia, Sylvain Payraudeau, Stefan Reichenberger, Piet Seuntjens
vPICO presentations
| Wed, 28 Apr, 11:00–12:30 (CEST)
HS2.3.4 EDI

Plastic pollution in freshwater systems is a widely recognized global problem with potential environmental risks to water and sediment quality. Furthermore, freshwater plastic pollution is also considered the dominant source of plastic input to the oceans. Despite this, research on plastic pollution has only recently expanded from the marine environment to freshwater systems. Therefore data and knowledge from field studies are still limited in regard to freshwater environments. Sources, quantities, distribution across environmental matrices and ecosystem compartments, and transport mechanisms remain mostly unknown at catchment scale. These knowledge gaps must be addressed to understand the dispersal and eventual fate of plastics in the environment, enabling a better assessment of potential risks as well as development of effective mitigation measures.
In this session, we explore the current state of knowledge and activities on macro-, micro- and nanoplastics in freshwater systems, including aspects such as:
• Plastics in rivers, lakes, urban water systems, floodplains, estuaries, freshwater biota;
• Monitoring and analysis techniques;
• Source to sink investigations, considering quantities and distribution across environmental matrices (water and sediment) and compartments (water surface layer, water column, ice, riverbed, and riverbanks);
• Transport processes of plastics at catchment scale;
• The role of river regulation structures, e.g. dams, navigation, flood control, etc., in plastic retention and transport
• Effects of hydrological extremes, e.g. accumulation of plastics during droughts, and short-term export during floods in the catchment;
• Degradation and fragmentation processes, e.g. from macro- to micro- and nanoplastics;
• Modelling approaches for local and/or global river output estimations;
• Legislative/regulatory efforts, such as monitoring programs and measures against plastic pollution in freshwater systems.

(Contributions with a strong focus on remote sensing of plastics are encouraged to be submitted to the session “Detecting and Monitoring Plastic Pollution in Rivers, Lakes, and Oceans”)

Convener: Daniel González-Fernández | Co-conveners: Freija MendrikECSECS, Merel KooiECSECS, Marcel Liedermann, Tim van Emmerik
vPICO presentations
| Thu, 29 Apr, 15:30–17:00 (CEST)
HS2.3.5 EDI

This session presents the works submitted to session HS2.3.5 “Fate and transport processes of pathogens and emerging contaminants at multiple scales” and to session HS6.9 “From short-term detection to long-term projections: complementing water quality assessments by combining modelling and remote sensing”.
HS2.3.5 Invited speaker: Dr. Liping Pang, ESR Christchurch, NZ
The occurrence of pathogens and an exponentially increasing number of contaminants in freshwater and estuary environments pose a serious problem to public health. There is a need to better understand the dominant processes controlling fecal indicator, pathogen and contaminant fate and transport at larger scales. Consequently, we welcome contributions that include both small and large-scale experimental and modelling studies with a focus on:
- The development of novel experimental and analytical methods to investigate fate and transport of fecal indicators, pathogens and emerging contaminants in rivers, groundwater and estuaries
- Hydrological, physically based modelling approaches
- Methods for identifying the dominant processes and for transferring fecal indicator, pathogen and contaminant transport parameters from the laboratory to the field or catchment scale
- Investigations of the implications of contamination of water resources for water safety management planning and risk assessment frameworks

HS6.9
Climate change and major socio-economic developments such as increasing population and expanding public water supplies that fail to adequately treat wastewater flows lead to significant water quality deterioration. An exponentially increasing number of contaminants and nutrients in freshwater and estuary environments pose a serious problem to public and ecosystem health. This part of the session focuses on regional and global water quality research where remote sensing and modelling are combined in order to complement a water quality assessment compared to one based on monitoring data only. Topics of interest:

- Remote sensing facilitating water quality model development and modelling
- Processing water quality data from remote sensing products across scales
- Improve water quality assessments

Public information:
This session presents the works submitted to session HS2.3.5 “Fate and transport processes of pathogens and emerging contaminants at multiple scales” and to session HS6.9 “From short-term detection to long-term projections: complementing water quality assessments by combining modelling and remote sensing”.
HS2.3.5 Invited speaker: Dr. Liping Pang, ESR Christchurch, NZ
The occurrence of pathogens and an exponentially increasing number of contaminants in freshwater and estuary environments pose a serious problem to public health. There is a need to better understand the dominant processes controlling fecal indicator, pathogen and contaminant fate and transport at larger scales. Consequently, this session's contributions include both small and large-scale experimental and modelling studies with a focus on:
- The development of novel experimental and analytical methods to investigate fate and transport of fecal indicators, pathogens and emerging contaminants in rivers, groundwater and estuaries
- Hydrological, physically based modelling approaches
- Methods for identifying the dominant processes and for transferring fecal indicator, pathogen and contaminant transport parameters from the laboratory to the field or catchment scale
- Investigations of the implications of contamination of water resources for water safety management planning and risk assessment frameworks

HS6.9
Climate change and major socio-economic developments such as increasing population and expanding public water supplies that fail to adequately treat wastewater flows lead to significant water quality deterioration. An exponentially increasing number of contaminants and nutrients in freshwater and estuary environments pose a serious problem to public and ecosystem health. This part of the session focuses on regional and global water quality research where remote sensing and modelling are combined in order to complement a water quality assessment compared to one based on monitoring data only. Topics of interest:

- Remote sensing facilitating water quality model development and modelling
- Processing water quality data from remote sensing products across scales
- Improve water quality assessments
Convener: Julia Derx | Co-conveners: Fulvio Boano, Ilona Bärlund, Jen DrummondECSECS, Martina Flörke, Stefan Simis, Margaret StevensonECSECS, Ting TangECSECS
vPICO presentations
| Fri, 30 Apr, 11:00–12:30 (CEST)
HS2.3.7 EDI

Our invited speaker is Lucy Marshall from the University of New South Wales, Sydney, Australia.

The application of multi-datasets and multi-objective functions has proven to improve the performance of hydrologic and water quality models by extracting complementary information from multiple data sources or multiple features of modelled variables. This is useful if more than one variable (runoff and snow cover, sediment or pollutant concentration) or more than one characteristic of the same variable (e.g., flood peaks and recession curves) are of interest.
Similarly, a multi-model approach can overcome shortcomings of individual models, while testing a model at multiple scales helps to improve our understanding of the model functioning in relation to catchment processes. Finally, the quantification of multiple uncertainty sources enables the identification of their individual contributions and this is critical for uncertainty reduction and decision making under uncertainty. In this aspect, Bayesian approaches emerge as very powerful tools for comprehensive handling of uncertainty in data, model structure and parameters.

This session welcomes contributions that apply one or more of the multi-aspects in hydrologic and water quality studies. In particular, we seek studies covering the following issues:
• Frameworks using multi-objectives or multi-variables to improve the identification (prediction) of hydrologic or water quality models
• Studies using multi-model or multiple-data-driven approaches
• Use of multiple scales or sites to improve understanding of catchment processes
• Assimilation of remote sensed data or use of multi-datasets to improve model identification
• Hypothesis testing with one of the multi-aspects
• Metaheuristics (e.g., Monte Carlo) or Bayesian approaches in combination with multi-aspects of model identification
• Techniques to optimize model calibration or uncertainty quantification via multi-aspect analyses
• Studies handling multiple uncertainty sources in a modelling framework
• Bayesian applications to address the problem of scaling (e.g. disparity between process, observations, model resolution and predictions) through hierarchical models
• Bayesian approaches to model water quality in data sparse environments
• Applications of Bayesian Belief Networks as decision support tools
• Application of machine learning and data mining approaches to learn from large, multiple or high-resolution data sets.

Convener: Anna Sikorska-Senoner | Co-conveners: Miriam GlendellECSECS, David C. Finger, Alberto Montanari, Ibrahim Alameddine, Lorenz AmmannECSECS, James E. Sample
vPICO presentations
| Wed, 28 Apr, 09:00–10:30 (CEST)

HS2.4 – Hydrologic variability and change at multiple scales

Programme group scientific officers: Kerstin Stahl, Alberto Viglione

HS2.4.2

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.

Convener: Stefan Hagemann | Co-conveners: Axel Bronstert, Harald Kunstmann, Rajib Maity
vPICO presentations
| Fri, 30 Apr, 11:00–12:30 (CEST)
HS2.4.3 EDI

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 often been neglected in projecting 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 always 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