Submarine Groundwater Discharge and Seawater Intrusion: Two sides of the
same coin that are rarely studied simultaneously
Abstract
Fresh submarine groundwater discharge (SGD) and seawater intrusion (SWI)
are complementary processes at the interface of coastal groundwater and
oceans. Multiple common drivers enable or limit SGD and SWI. However, we
find that SGD and SWI are rarely studied simultaneously. In this
meta-analysis, we synthesize 1298 publications, examining drivers of SGD
and SWI, where and why they are studied, and at which scales they are
impacted by their drivers. Studies of SGD and SWI accumulate in urban
coastal basins with high gross domestic product (GDP), and high
permeabilities, where measurable groundwater fluxes are expected. We
find, that studies investigate various drivers, but rarely assess the
scales they act at. Effects of temporally recurring processes (e.g.,
tides) are studied more often and are better known than effects of
spatial variability (e.g., permeability). Future studies should
investigate SGD and SWI simultaneously, report impact scales of drivers
explicitly and explore unchartered coastlines.