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Utilizing multichannel electrical resistivity methods to examine the dynamics of the fresh water–seawater interface in two Hawaiian groundwater systems

Journal of Geophysical Research C: Oceans

By:
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DOI: 10.1029/2011JC007509

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Abstract

Multichannel electrical resistivity (ER) measurements were conducted at two contrasting coastal sites in Hawaii to obtain new information on the spatial scales and dynamics of the fresh water–seawater interface and rates of coastal groundwater exchange. At Kiholo Bay (located on the dry, Kona side of the Big Island) and at a site in Maunalua Bay (Oahu), there is an evidence for abundant submarine groundwater discharge (SGD). However, the hydrologic and geologic controls on coastal groundwater discharge are likely to be different at these two sites. While at Kiholo Bay SGD is predominantly through lava tubes, at the Maunalua Bay site exchange occurs mostly through nearshore submarine springs. In order to calculate SGD fluxes, it is important to understand the spatial and temporal scales of coastal groundwater exchange. From ER time series data, subsurface salinity distributions were calculated using site-specific formation factors. A salinity mass balance box model was then used to calculate rates of point source (i.e., spatially discreet) and total fresh water discharge. From these data, mean SGD rates were calculated for Kiholo Bay (∼9,200 m3/d) and for the Maunalua Bay site (∼5,900 m3/d). While such results are on the same order of magnitude to geochemical tracer-derived SGD rates, the ER SGD rates provide enhanced details of coastal groundwater exchange that can enable a more cohesive whole watershed perspective.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Utilizing multichannel electrical resistivity methods to examine the dynamics of the fresh water–seawater interface in two Hawaiian groundwater systems
Series title:
Journal of Geophysical Research C: Oceans
DOI:
10.1029/2011JC007509
Volume
117
Issue:
C2
Year Published:
2012
Language:
English
Publisher:
Wiley
Contributing office(s):
Pacific Coastal and Marine Science Center
Description:
C02012; 12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research C: Oceans
Country:
United States
State:
Hawai'i
Other Geospatial:
Big Island;Kiholo Bay;Wailupe Beach