LAUSR

The streambed constitutes the physical interface between the surface and the subsurface of a stream. Across all spatial scales, surface water-groundwater interactions are controlled by the physical properties of the streambed. Streambed properties such as topography or hydraulic conductivity are continuously altered through erosion and sedimentation processes. Recent studies from the fields of ecology, hydrogeology and sedimentology provide field evidence that sedimentological processes themselves can be heavily influenced by surface water-groundwater interactions, giving rise to complex feedback mechanisms between sedimentology, hydrology and hydrogeology. More explicitly, surface water-groundwater exchanges play a significant role in the deposition of fine sediments, which in turn modify the hydraulic properties of the streambed. We explore these feedback mechanisms and critically review the extent of current interaction between the different disciplines. We identify opportunities to improve current modeling practices. For example, hydrogeological models treat the streambed as a static rather than a dynamic entity, while sedimentological models do not account for critical catchment processes such as surface water-groundwater exchange. A blueprint for a new modeling framework is proposed that bridges the conceptual gaps between sedimentology, hydrogeology and hydrology. Specifically, this blueprint (1) fully integrates surface-subsurface flows with erosion, transport and deposition of sediments, and (2) accounts for the dynamic changes in surface elevation and hydraulic conductivity of the streambed. The opportunities for new research within the coupled framework are discussed.