We would like to draw your attention to two IAHS related sessions in the Hydrological Sciences (HS) programme at the upcoming virtual EGU General Assembly (19-30 April 2021) related to the Unsolved Problems in Hydrology (UPH) initiative and the Panta Rhei decade.

HS1.2.3 Pathways towards solving the Unsolved Problems in Hydrology (UPH) 

https://meetingorganizer.copernicus.org/EGU21/session/39751 

The IAHS in collaboration with the Hydrology Divisions of EGU and AGU as well as the IAH, launched in 2017 a public consultation process for compiling a list of unsolved scientific problems in hydrology which resulted, in 2019, in a set of 23 Unsolved Problems in Hydrology (UPH) (see https://doi.org/10.1080/02626667.2019.1620507).

The UPH are articulated around 7 themes: Time variability and change, Space variability and scaling, Variability of extremes, Interfaces in hydrology, Measurements and data, Modelling methods, and Interfaces with society. Some of the UPH may have already been partially studied. Recent research may shed light on how to move forward in a more holistic way. A crucial issue is to put together fragmented knowledge to address the questions raised and enhance coherence in hydrological sciences.

The purpose of this session is to discuss progress in any of the 23 UPH. Contributions are encouraged to either:
- 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.

Authors are asked to clearly state the UPH their work refers to or could contribute to solve. The authors may also reflect on how the community could evaluate if an UPH can be considered solved or not.

HS1.2.4 Panta Rhei: hydrology, society & environmental change

https://meetingorganizer.copernicus.org/EGU21/session/39110

This session is organized as part of the IAHS Panta Rhei hydrological decade 2013- 2022 focusing on gains in our understanding of water cycle processes by focusing on their changing dynamics in respect of interactions and feedbacks with human systems. 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.

This session welcomes contributions that contribute to and critically reflect the following synthesis topics:
1) Theoretical/conceptual framework for understanding changes in hydrology and society;
2) Coevolution and emergent phenomena;
3) dynamic models;
4) Data needs and acquisition;
5) Benchmark datasets in various context and scales, including human-flood, human-drought, agricultural, transboundary and global systems;
6) Case studies from Panta Rhei working groups, IAHS Commissions and beyond.

Please note that the deadline is 20th January 2021 at 13:00 Central Europe Time.