Estimates of groundwater recharge and discharge rates are needed at many different scales for many different purposes. These include such tasks as evaluating landslide risks, managing groundwater resources, locating nuclear waste repositories, and estimating global budgets of water and greenhouse gasses. Groundwater Fluxes Across Interfaces focuses on scientific challenges in: the spatial and temporal variability of recharge and discharge; how information at one scale can be used at another; and the effects of groundwater on climate and vice versa.