I probably have to formulate them differently. However at present my points are
1- What future for process based modelling beyond persistent dilettantism ? How can we converge towards new types of open models infrastructures for hydrology where the crowd can contribute, big institutions do not dominate, and reinventing the wheel will not be necessary anymore ?
2 - How to solve the energy budget, the carbon budget and the sediment budget together to constrain hydrologic models results ?
3 - Which new mathematics to choose for the hydrology of this century ? Does new hydrology (Earth System Science) needs new mathematics ?
4 - Will machine learning have a real role in hydrological modelling ?
5 - How can we really cope hydrological modeling with remote sensing measures ?
6 - How plants and grass work and interact with soil and atmosphere to produce evaporation ? Can we converge to unifying concepts that overcome present fragmented understanding ?
7 - How can we detect and measure spatial hydrological patterns ?
8- Does hydrology needs non-equilibrium thermodynamics or even a new type of thermodynamics ?
9 - How can we do hydrology science more open and replicable ?
10 - How dominant hydrological processes emerge and disappear across the scales. What tools are needed to follow the entanglement of processes ? Will we be finally able to cope with feedbacks among processes?