Contaminant hydrology over the last century has used physically-based solute transport models that solve equations of advection and diffusion to estimate the fate and transport of contaminants. In the last decade, time variant transit time models have been proposed as a stochastic alternative to solve solute transport in a more time efficient manner. Transit time models follow a top-down approach that require fewer model parameters than classic advection-diffusion approaches. The caveat being that it requires high resolution (temporally) data for concentration of solutes in the hydrologic system.

With the advent of advanced laser-based picarro devices, measuring stable isotopes of hydrogen and oxygen in water have become more feasible. These stable isotopes of water can also be used to infer the transit time model parameters and provide mean catchment transit time information (i.e. on average how long a water molecule spends in the catchment after first entering into the soil). This becomes highly relevant in agricultural catchments where the applied fertilisers and pesticides can find their way to the groundwater pool in a short span of time that may later be consumed for domestic purposes.

This session will bring together a panel of experts on both the top-down (transit time modeling) and the bottom-up (physically-based models) approaches to modeling solutes in streams. After a short introduction by the experts, the session will follow an open discussion where participants can engage with the panel. The discussion will conclude with a summary from the panelists.

This will be the sixth edition of Meet the Expert session. This session is organised in cooperation with the Young Hydrologic Society (http://younghs.com/) and the EGU Geomorphology Section (GM).