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Geologic influence on groundwater salinity drives large seawater circulation through the continental shelf
Author(s) -
Michael Holly A.,
Scott Kaileigh C.,
Koneshloo Mohammad,
Yu Xuan,
Khan Mahfuzur R.,
Li Katie
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070863
Subject(s) - groundwater , aquifer , continental shelf , geology , submarine pipeline , groundwater flow , seawater , salinity , hydrology (agriculture) , lithology , environmental science , oceanography , geotechnical engineering , petrology
Abstract Observations of offshore freshened groundwater and saline groundwater discharge along continental shelves have important implications for water resources, ecosystem function, and the composition of the ocean, but they cannot be explained by basic theory. We show that these independent observations are linked and result from processes that drive variable‐density groundwater flow through the spatial heterogeneity that is ubiquitous in geologic formations. We use lithologic data to develop geostatistical models that mimic the architecture of coastal aquifers. Simulation of groundwater flow and salt transport through these random realizations shows that heterogeneity produces spatially complex subsurface salinity distributions that extend tens of kilometers offshore, even at steady state. The associated density gradients drive high saline groundwater circulation rates that cannot be predicted by equivalent homogeneous models. Results suggest that these phenomena may be common along continental shelves, potentially altering estimates of ocean chemical budgets and impacting coastal water management for future generations.