Submarine Groundwater Discharge (SGD) and Associated Nutrient Fluxes to the Coastal Ocean

Abstract

Submarine groundwater discharge (SGD) is an almost ubiquitous coastal feature that is driven by a combination of climatologic, hydrogeologic, and oceanographic processes. For example, terrestrial hydraulic gradients that reflect both short- and long-term climatic conditions almost always transport both surface- and groundwater toward the coast. In coastal oceans, physical processes such as wave setup, tidal pumping, and density-driven circulation may impact these hydraulic gradients and thus affect rates of SGD (Fig. 11.1.1) (Johannes 1980; Church 1996; Li et al. 1999; (year?); Taniguchi 2002; Burnett 2003). Although only fresh groundwater discharge has traditionally been accounted for in numerical simulations of coastal water budgets, saline groundwater discharge may be equally or even more important in terms of material transport across land/sea margins (Li et al. 1999; Kim et al. 2002; Burnett 2003; Kim et al. 2003a). In this chapter, we therefore define SGD to consist truly fresh groundwater, recirculated seawater, or a composite thereof.