Until relatively recently, surface water and groundwater have been considered to a large degree as separate entities by hydrologists, engineers, and decision makers. As a consequence, the importance and relevance of interactions between groundwater and surface water for freshwater ecosystems has often been underestimated. However, research into groundwater-surface water interactions has undergone a paradigm shift in understanding in recent years, leading to these systems being redefined as integral components of an aquifer-river continuum with strong bi-directional influences between rivers, aquifers and interconnecting hyporheic zones.

A rapidly expanding number of research projects are now investigating the implications of hyporheic exchange on the transport and transformation of nutrients and contaminants within river networks, and on controls to heat, oxygen, and organic matter budgets available to microorganisms and macroinvertebrates in streambed sediments. Research is also focusing on the response of hyporheic exchange fluxes to environmental and climatic controls at different spatial and temporal scales (e.g. river channel, alluvial aquifer, regional groundwater flow). In addition, there is a need to better understand the links between hydrological, biogeochemical, and ecological process dynamics in hyporheic zones and their implications for fluvial ecology.

We consider up- and downscaling and the development of a general conceptual framework for groundwater-surface water interfaces as among the most urgent challenges of hyporheic zone research. Consequently, we particularly welcome contributions that aim to close these knowledge gaps and address either scaling issues or the development of a general conceptual framework.

In addition, this session also solicits both field-based and modelling studies with a focus on:

- The development and application of novel experimental methods to investigate physical, biogeochemical and ecological conditions at the groundwater-surface water interface in both rivers and lakes;

- Investigations of the role of hyporheic processes for the retention and natural attenuation of nutrients and pollutants, particularly with respect to impacts on surface water and groundwater quality;

- Hydrological, biogeochemical and ecological modelling approaches (e.g. transient storage models, coupled groundwater - surface water models etc.);

- Investigations of the implications of groundwater - surface water interactions for management and risk assessment frameworks with regard to the European Water Framework Directive.


The following solicited speakers are confirmed for the session:

Christopher Lowry (University at Buffalo, The State University of New York)
'Hyporheic expansion and contraction due to hydrologic forcing'