Quantifying submarine groundwater discharge in the coastal zone via multiple methods

Area of Science:

• * Hydrogeology and Marine Biogeochemistry: Investigating the critical interface between terrestrial groundwater systems and coastal marine environments.

Background:

• * Submarine groundwater discharge (SGD) is increasingly recognized as a key pathway for nutrient and chemical transport from land to sea.
• * SGD is characterized by significant spatial and temporal variability, making accurate assessment challenging.
• * Understanding SGD is crucial for managing nearshore water quality and biogeochemical budgets.

Purpose of the Study:

• * To review the scientific and management significance of SGD.
• * To examine and compare various methods for assessing SGD magnitude and chemical fluxes.
• * To present findings from a series of intercomparison experiments conducted in diverse hydrogeologic settings.

Main Methods:

• * Review of established and novel techniques for measuring SGD.
• * Conducting five intercomparison experiments involving multiple methods across varied geological terrains (coastal plain, karst, glacial till, fractured rock, volcanic).
• * Analysis of spatial and temporal variability in groundwater seepage and associated chemical fluxes.

Main Results:

• * SGD is a ubiquitous process in coastal areas globally.
• * Each measurement technique for SGD has distinct advantages and disadvantages.
• * Significant variability necessitates measurements across broad spatial and temporal scales.

Conclusions:

• * Accurate assessment of SGD requires employing multiple measurement techniques simultaneously.
• * Long-term monitoring is essential to capture tidal, storm, and seasonal influences on SGD.
• * Integrated approaches are vital for robustly quantifying SGD and its impact on marine ecosystems.