A key research topic in hydrology concerns the relationship between water storages and their residence times. Such aspects are fundamental to describe water fluxes across the hydrological cycle, from the atmosphere to the groundwater. Knowing the residence time or water ages can be crucial for understanding

1. the dynamics of canopy water storage,
2. the interplay between rapid preferential and slow diffuse flow at the surface,
3. flow in the unsaturated zone, the groundwater, and their interactions.

Furthermore it can help to assess vulnerability and the recovery-time of hydrological systems impacted by pollution, to quantify quality problems due to climate change impacts, and to evaluate numerical groundwater models. Estimates of the Mean Residence Time (MRT) or age distributions of groundwater are primarily possible by tracer measurements (e.g. dye, isotope and gas-tracers, etc.) and numerical modelling (e.g. direct simulation of age).

This session aims at combining knowledge about the characteristics and controls of water residence times and water ages from recent studies and applied resource management across the entire hydrosphere.

Solicited Speakers:
Peter Troch, University of Arizona, USA
James Kirchner, ETH Zürich, Switzerland
Gianluca Botter, University of Padova, Italy
Luc Aquilina, University of Rennes, France