History and evolution of seepage meters for quantifying flow between groundwater and surface water: Part 2 – Marine settings and submarine groundwater discharge

Abstract

This review of studies that quantified fluxes with seepage meters in marine settings in the last decades shows the historical evolution of this device and the knowledge acquired during this period. Coastal environments are differentiated from freshwater settings due to water salinity and the effects of tides and waves that have important implications for the measurement approach and generated results. The framework in which seepage meters have been used in marine settings has evolved in parallel to the understanding of submarine groundwater discharge. This review of seepage meter research shows: an uneven distribution of studies in the world with some densely-studied regions and an absolute lack of data in other regions; a dominance of studies where only seepage meters were used compared to studies that combined seepage meter measurements with values determined with radioactive tracers or hydraulic calculations; and a variety of publication outlets with different focuses (hydrology, oceanography or multidisciplinary). The historical overview of the research conducted with seepage meters shows the wide range of seepage meter applications – from simply measuring fluxes at local scales to larger studies that extrapolate local results to estimate fluxes of water, nutrients, and other solutes at regional and global scales. A variety of automated seepage meters have been developed and used to better characterize short-term groundwater-seawater exchange, including the effects of waves and tides. We present recommendations and considerations to guide seepage meter deployment in marine settings, as seepage meters are still the only method that quantifies directly the interaction between groundwater and surface water.