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Quantifying hydrological and tidal influences on groundwater discharges into coastal waters
Author(s) -
Prieto Carmen,
Destouni Georgia
Publication year - 2005
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2004wr003920
Subject(s) - submarine groundwater discharge , groundwater , seawater , brackish water , aquifer , hydrology (agriculture) , groundwater discharge , groundwater flow , salinity , environmental science , geology , oceanography , geotechnical engineering
In coastal aquifers the dynamic mixing zone between intruding seawater and fresh groundwater constitutes a zone of salinity transition that may supply brackish groundwater along with chemical tracers and nutrients to coastal waters. Tidal influence has been proposed as a possible mechanism for enhancement of recirculated seawater, total submarine groundwater discharge (SGD), and associated tracer loading through salinity transition zones into coastal waters. We show that tidal oscillation may, for relatively low SGD cases, considerably increase the average recirculated seawater component of total SGD relative to nontidal conditions. High SGD cases, however, are dominated by and require large fresh groundwater flow components also under tidal conditions; this result is obtained from a wide range of different groundwater simulation scenarios and is supported by direct comparison with field data from different reported high‐SGD sites in the world. For cases with hydrologically limited fresh groundwater flow directly into the sea we propose that observed excessive coastal loading of groundwater‐derived tracers may be the result of large groundwater flow and transport into unmonitored coastal stream reaches, in addition to SGD.