UN 2023 Water Conference: ISC Policy Brief

This policy brief of the International Science Council (ISC), which includes Christophe Cudennec (IAHS Secretary General) as a Contributor, for the UN 2023 Water Conference highlights the importance of science and the importance of actionable knowledge in responding to current global water crises as well as emerging and future challenges.


The brief groups the numerous water challenges into four main categories with associated examples and focal areas that each demand different scientific responses. Together with concluding advice, this policy brief aims to efficiently engage with policy- and decision-makers and other stakeholders at UN- and Member States-level to translate scientific insights into tangible improvements and support the water-related Sustainable Development Goals (SDGs) and the achievement of the 2030 Agenda.

Click here for more information and to download the brief.

Science for Water Solutions Decade

The next IAHS decade will be dedicated to local solutions under the global water crisis. The short name will be HELPING, and stand for Hydrology Engaging Local People IN one Global world.

The new topic makes a nice trilogy with the previous two decades, ranging from Predictions (PUB) to Change (Panta Rhei) to Solutions (HELPING).



Explanation of Acronym

Helping = we need to collaborate, share and help each other to overcome the water crisis.

Hydrology = Hydrological sciences should underpin management and governance of water resources; thus, we need better understanding of impact from global drivers at local scales and vice versa.

Engaging = co-creation of knowledge includes shared capacity, common learning and community engagement. 

Local = water phenomena and problems are often unique at the local scale and solutions must therefore be solved considering local needs and knowledge.

People = the purpose is to connect people (scientists, practitioners, communicators and the general public) with similar interests to co-design, accumulate and transfer hydrological knowledge worldwide. 

IN one = together we can advance science faster than individually to overcome shared or similar challenges.

Global world = the Planet is in an emergency state with complex water-cycle interactions, which needs urgent actions to not leave anybody or any catchment behind.

Community Process

The topic of the new decade distilled from the outcome of the Córdoba workshop and the preceding vivid discussions online, followed by a simple survey on preference of selected topics. 130 persons answered on which topic they wanted to engage with (multiple choices) resulting in top scores for:

·         global and local hydrological interactions (60%);
·         water security (40%);
·         empowering people and science communication (35%).

Based on this the selected writing team (see below) has now launched a condensed Concept Note, which is found at the IAHS website under Initiatives/Scientific Decade. https://iahs.info/Initiatives/Topic-for-the-Next-IAHS-decade.do 

Actions and What to do

The next step is to define actions, work clusters and leaders for initiating the new decade. The Forum will be open for suggested themes and volunteers. In addition, two splinter meetings will be held at EGU on Thursday 27 April and a dedicated workshop will be held at TU Wien on Saturday the 29 April. Register here!

Click here to access more information about the Next Decade.

Workshop agenda 29 April at Technical University of Vienna

09.00 – 10.00 Intro and discussion of overall aim and expected outcome
10.00 – 10.30 BREAK
10.30 – 12.00 Brainstorming ideas on Actions and results
12.00 – 12.30 Reporting in Plenum
12.30 – 13.00 Discussion, Synthesis and Decision
13.00 – 14.00 LUNCH
14.00 – 15.00 Clustering the defined actions
15.00 – 15.30 Discussion and Decision
15.00 – 16.00 Wrap-up and Way forward
16.00 THE END


The original outcome document was consolidated from reflective and creative input by the IAHS community in the Cordoba workshop (50 persons) during three days; online meetings (100 persons) in three time-zones; posts in a forum (40) of the IAHS website. The condensed concept note was drafted by a smaller team of writers (15 persons) who contributed actively in organising the process and represents different parts of IAHS:

The IAHS Officers and Córdoba workshop organisers: Berit Arheimer, Christophe Cudennec, Günter Blöschl, Salvatore Grimaldi, Maria José Polo
Online conveners or co-conveners: Barry Cloke, Chris Leong, Stacey Archfield, Giova Mosquera, Melody Sandells, Jean-Marie Kileshye Onema
The Early Career Committee: Moctar Dembélé, Bertil Nlend
Early carrier opinion paper in HSJ (lead author): Tessa van Hateren
South America initiative: Pedro Chaffe

Abstract submission deadline extended to 10 March for Panta Rhei Symposium

The Panta Rhei Symposium, which marks the end of the IAHS Scientific Decade on Change in Hydrology and Society, will take place in GFZ Potsdam, Germany from 10 - 11 July 2023.  The objective is to present key results, discuss the way forward, and celebrate the achievements of Panta Rhei – Change in Hydrology and Society

The abstract deadline has been extended to 10 March. 

For information on abstract submission and registration visit here.  

As the symposium takes place immediately before the IUGG General Assembly, and in close proximity to Berlin, you should take this into account when making your travel arrangements.

Among the wider IUGG/IAHS programme, session H01 specially focuses on Panta Rhei Synthesis: Change in Hydrology and Society.

Córdoba Workshop & Updated Schedule for the Next Scientific Decade

IAHS continues to search for a new topic for the Next Scientific Decade. The workshop held in Córdoba 1-3 February was engaging with almost 50 scientists from across the globe participating in intense discussions resulting in many different suggestions and ideas. The consolidated outcome document as well as an updated time-plan is now available on the IAHS website.  The discussions indicate that the 3rd decade will be solution oriented and will search to find a scientific basis for understanding and reducing the local effects from the rising global water crisis in the Anthropocene.

However, we still search to narrow the focus, if possible, and to find an inspiring, overarching and catchy name. Therefore, we would like to encourage all members to participate in our quick survey by answering 1-3 simple questions. Once you have read and had a chance to reflect upon the outcome document, please click below and answer (anonymously) the survey by 28 Feb at the latest: Click here for the survey.


The Córdoba outcome document is a consolidation of the reflective and creative input by the IAHS community in: 

·        the Cordoba workshop (50 people) for three days,
·        online meetings (100 people) in three time-zones,
·        posts in a forum (40 comments) of the IAHS website.


Save the date – 29th April
The next step in the process will include a small team of 15 people who will draft a concept note, which will be available for commenting by mid-March and communicated at the UN Conference On Water in New York 22-24 March. A splinter meeting will be organised at EGU on Thursday 27 April, followed by a workshop to be held at Technical University of Wien on Saturday 29 April. 

Please register here for the workshop in Vienna on Saturday 29 April where we will discuss Actions and Leadership for the Next Scientific Decade (detailed agenda to follow at a later date). All completed registration forms must be sent to [email protected]



2023 Falkenmark Award winner announced

The winner of the first IAHS Falkenmark Award for best PhD thesis has been announced as Dr Afua Owusu from Ghana for her innovative interdisciplinary approach to re-operation of reservoirs for environmental flows.

Afua focussed on the success and failures to implement dam re-operations for environmental flows using an interdisciplinary approach. She managed to both evaluate global challenges and identify key factors for successful dam re-operation, using surveys as well as multi-sectorial trade-offs in the Lower Volta River Basin in Ghana, making use of an Evolutionary Multi-Objective Direct Policy Search.

The Falkenmark Award for best PhD thesis:

Recognises outstanding contributions to hydrological understanding of water scarcity and water supply.
Is granted every year, starting 2023 (nomination must be submitted no later than 31 December 2022).
Highlights the importance of capacity building and knowledge/data gathering in financially disadvantaged countries.

Eligible nominees:

Grew up in a financially disadvantaged country.
Performed the PhD work in one or more financially disadvantaged countries.
Holds a PhD certificate, which is dated within the last 2 years.

The award will be presented at the IUGG 2023 General Assembly

Deadline for submitting abstracts to IUGG 2023 extended to 21 February

The deadline for submitting abstracts and applications for travel grants to attend the IUGG General Assembly 2023, which will be held in Berlin, Germany, has been extended to 21 February 2023.

The IAHS-led programme will be over the first half of the Assembly ie 12-16 July 2023.

Details of the IAHS symposia:
IAHS standalone symposia: click here     
Inter-Association symposia led by IAHS: click here  
and several other symposia led by sister associations with an IAHS involvement and hydrological perspective: click here   

Final Call: Abstracts for the IUGG 2023 General Assembly in Berlin

The 28th IUGG General Assembly will be held July 11-20, 2023 at the CityCube in Berlin, Germany. This is a special opportunity for participants from around the world to come together and share their science and culture. Join us for a host of scientific activities, including special public lectures, keynote Union lectures and a wide variety of themed sessions.

The IAHS-led programme will be over the first half of the Assembly ie 12-16 July 2023.

Abstract submission and online registration are now open on the website:
Abstracts must be submitted by 14 February 2023: click here  
Registration: click here    
Submission of a travel grant application: click here

Details of the IAHS symposia:
IAHS standalone symposia: click here     
Inter-Association symposia led by IAHS: click here  
and several other symposia led by sister associations with an IAHS involvement and hydrological perspective: click here   


Opportunity to contribute remotely to the IAHS Next Scientific Decade

After two successful decades (PUB and Panta Rhei), IAHS want to once more boost the community through launching a third topic for collaborative efforts in hydrological sciences. The overall aim of the Scientific Decade is to accumulate knowledge and streamline research efforts worldwide. 

An open in-person event will be held 1-3 February 2023 in Córdoba, Spain, to decide on the topic for the next scientific decade. Ideas are already being discussed in the online forum. To enable a wider community input we are running three online sessions in different time-zones for remote discussions to further feed in to the plenary sessions in Cordoba (see questions below). 

To join a free online session you need to register in advance:

Oceania/Asia region organised by Barry Croke and Chris Leong: Monday 30th January 2pm AEDT https://www.eventbrite.com.au/e/iahs-scientific-decade-oceaniaasia-region-tickets-522203222897  

Europe/Africa region (part 1) organised by Christophe Cudennec and Jean-Marie Kileshye: Wednesday 1st February 10-12 CET https://www.eventbrite.com/e/iahs-cordoba-workshop-online-session-for-europeafrica-time-zones-cet-tickets-523784773357 

Europe/Africa region (part 2) organised by Melody Sandells: Thursday 2nd February 10:30-12:30 CET https://www.eventbrite.com/e/iahs-cordoba-workshop-2nd-online-session-for-europeafrica-time-zones-cet-tickets-524484626637 

North/South America region organised by Stacey Archfield and Giova Mosquera: Tuesday 31st January 1-3pm EST https://www.eventbrite.com/e/next-iahs-scientific-decade-discussion-south-north-america-tickets-524650562957 

Questions to be discussed and reported in Córdoba:

Input requested for Plenum 1 Feb at 14 hrs CET:

1. What defines a successful Scientific Decade?
2. What do we want to achieve in the long-term and short-term, respectively?

Input requested for Plenum 2 Feb at 10 hrs CET:

1. What are the current drivers/trends in Fundamental and Applied Research?
2. What are the societal needs of scientific results?
3. Where to position IAHS? (vs other global scientific communities)

Input requested for Plenum 2 Feb at 14 hrs CET:

1. Brainstorm potential topics (and sub-topics/science questions) of the Next decade!
2. Identify short and catchy names
3. Make a brief SWOT analysis for each one (Strengths, Weaknesses, Opportunities, Threats)

NOTE: the voting for new topic will only be made by participants in Cordoba – and announced in the evening (CET) of Day 2!

Input requested for Plenum 3 Feb at 10 hrs CET:

1. Identify sub-topics, science questions and Results of the Next Scientific Decade!
2. Suggest an organisational structure and communication/work activities, based on previous experience from global community building.

Please, join us and contribute to the community effort to define the next scientific decade!

The Ultimate IAHS Frisbee Tournaments

















The 2021 IAHS ultimate frisbee game: a technical note

In the troubled times of 2021, the IAHS ultimate frisbee game was like no other. For the first time in its history, the game was postponed for one year and was held in 2022. Nonetheless, the game was highly anticipated and therefore it attracted a record number of participants: around 60! 

Following what any hydrological modeller should do before applying its model, and because these conditions had never been encountered before, a differential split sample test was applied to the participants. First, the crowd of participants was split into two equal parts. Second, contrasted samples of participants were constituted: on one side the dark-coloured shirt players, on the other side the light-coloured shirt players. This thorough protocol enabled to assess the robustness of ultimate players. 

Due to the high number of players and the subsequent high number of necessary operations to process, it was unanimously decided to parallelize the event. Two games were played in parallel, half of the dark-coloured shirt team played against half of the light-coloured shirt team, while the other two halves played against each other. This old-fashioned manner to run the game faster did not satisfy all players. Indeed, some of the youngest, and therefore geekiest, players, decided that using the cloud was a better option. Unfortunately for them, throwing Frisbee disks to clouds only resulted in losing them, although one of them was found back into the nearby Lez River. 

The boundaries between the two games were porous and some unintended interactions between the two games were noted. Still, parallel computing, although not being a 100 % perfect method, has a bright future ahead, and outperformed cloud computing. This report being a technical note, we decided to focus on the methodology only and the results will not be detailed here. For more details, the readers are invited to read our next papers. 

The 2019 IAHS frisbee game: an ensemble approach

The 2019 IAHS ultimate frisbee game was held at the Montréal Champ-de-Mars green area, in front of the City townhall. The participants decided to constitute two groups, the Ensemble Kalman Filter (EnKF) team and the Particle Filter team, aiming at comparing these two data assimilation approaches that are widely used in hydrology to incorporate real-time data into models. 

A dozen of participants were in each team, constituting the members (or particles) of these two ensembles. As the EnKF generally necessitates less members than the Particle filter, the EnKF team started the game with high confidence. Consequently, after the first observation of a Frisbee disk was made on the field, they scored the first point with high accuracy. 

Confident with this early victory, all members of the EnKF team decided to stay close together before the next Frisbee observation. On the other side, the Particle filter team adopted a different tactic: applying the well-known principle of natural selection, a.k.a. the sequential importance resampling, its particles performing the less were simply discarded from the team. To keep a similar number of players, its best elements were replicated. While this could have lead to a lack of diversity in the Particle filter, this methodology proved to be efficient for the next Frisbee disk observations. Oppositely, due to a too high proximity, the EnKF team members collided and suffered from a collapse and could not score again. 

While the game resulted in a large victory for the Particle Filter team, the EnKF team strongly argued that if multiple spatially-distributed observations of Frisbee disks were made, instead of one at a time, the Particle Filter team would have struggled and they would have easily won the game. That might be further investigated in following games. 

View our Facebook page for more about this fun event in Montpellier!


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