Understanding hydrological processes that occur when surface waters and groundwater interact is important for water management and resource allocation. The dynamics of groundwater-surface water exchanges also significantly affect the functioning of aquatic ecosystems, pollutant and nutrient transport as well as the quality and quantity of water supply for domestic, agricultural, and recreational purposes.

In recent years hydrologic research has been marked by a clear shift from the traditional perception of ground- and surface water as two separate entities towards a more holistic understanding. Groundwater and surface water (rivers and lakes) are integral components of a hydrologic continuum with strong feedbacks between both compartments and their interconnecting hyporheic zone.

A large suite of modeling tools and new field methods, including geophysical, hydrological and geochemical approaches, have been developed and refined to characterize and quantify the relevant processes at different spatial (e.g. river channel, alluvial aquifer, catchments) and temporal scales (e.g. event, seasonal or long-term trend based). Interdisciplinary studies that bridge hydrology, biogeochemistry and aquatic ecology address topics such as the transport and transformation of nutrients and contaminants within river corridors or the controls for supply of heat, oxygen, and organic matter to microorganisms and macro-invertebrates in streambed sediments. However, despite numerous methodological advances and a generally improved small-scale process understanding a unifying synthesis with respect to the role of groundwater-surface water interactions for matter fluxes and water quality or the health of aquatic ecosystems at larger, management-relevant scales is still missing. Also the link between field based observations and modelling is currently still weak. Upscaling the findings from reach-scale studies to the catchment-scale and the incorporation of the results into modeling frameworks is critical for an effective management of connected water resources.

This session solicits contributions from hydrogeologists, stream ecologists, microbiologists, ecohydrologists, geochemists, geomorphologists, coastal oceanographers and landscape ecologists in order to discuss new developments in field and analytical methods, modeling approaches and techniques to reduce uncertainties in prediction of groundwater-surface water interactions and to better understand spatial and temporal variability of exchange.