In November 2017 IAHS launched the new initiative to generate the 23 unsolved problems in Hydrology that would revolutionise research in the 21st century with a YouTube video.

The generation of questions is open to everyone and will be distilled through discussion on the IAHS LinkedIn group https://www.linkedin.com/groups/13552921 We aim to finalise the questions in Spring 2018.

We already have entries over a wide range of topics with draft questions and comments including:

Can we trade space for time in hydrology? By Ross Woods

How can we identify the independent factors determining a nonlinearly evolving hydrologic response? By Elena Volpi on behalf of ICSH – STAHY Commission

How can one identify the optimal sample dimension to use in multivariate analysis with copula functions? By Elena Volpi on behalf of ICSH – STAHY Commission

How can we detect and attribute change in flood characteristics? By Elena Volpi on behalf of ICSH - STAHY Commission

Sudden and abrupt changes of water management conditions? By Andreas Schumann

Natural heterogeneity, thermodynamics and (yet again) closing the water balance, by Markus Hrachowitz

Why do we see long term cycles in temperature, rainfall and river flows? By Alberto Montanari

Is it possible to remove the independence condition in the multivariate frequency analysis (e.g., when using Copulas)? By Salvatore Grimaldi

Closing the mass-age balance by measurement by Wouter Berghuijs

What controls the long term water balance, apart from aridity? By Ross Woods

How to determine the snow water equivalent in mountain regions? By Simon Gascoin

What is the value of soil moisture observations for hydrologic predictions? By Luca Brocca

Feel free to add your own draft question or add a comment to the existing discussion on the group.