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Role of aquifer heterogeneity in fresh groundwater discharge and seawater recycling: An example from the Carmel coast, Israel

Journal of Geophysical Research C: Oceans

By:
, , , , ,
DOI: 10.1029/2007JC004112

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Abstract

A case study is shown in which the pattern of submarine groundwater discharge and of seawater recycling is controlled by local hydrogeological variability. The coastal aquifer in Dor Bay is composed of two units: a partly confined calcaranitic sandstone (Kurkar) and an overlying loose sand. Groundwater in the Kurkar has elevated activities of 222Rn (∼390 dpm/L) and relatively low 224Ra/223Ra activity ratios (3–4), while the sand groundwater is significantly less radiogenic (6–90 dpm/L) and shows higher 224Ra/223Ra ratios. Groundwater discharging from sand-covered areas of the bay has salinities of 16–31 and an average 222Rn activity of 168 dpm/L, which lies on a mixing line between Rn-rich Kurkar fresh water and Rn-poor seawater. Another key observation is that seawater infiltrates to some extent into onshore sand groundwater, while the fresh water within the submarine Kurkar can be traced up to 40 m offshore. This implies that while fresh water mainly discharges from the Kurkar unit, seawater recycling is limited to the loose sand, and that the discharge from sand-covered areas is a mixture of Kurkar water with recycled seawater. Advection rates from the bay floor were calculated from Rn time series and found to vary between 0 and 36 cm/d, correlating negatively with bay water depth. The average flux was 8.1 cm/d, and it did not seem to change much during March, May, and July 2006. The average amount of fresh water discharging to the bay was 5.0 m3/d per meter of shoreline. Radon activity in the sand groundwater also fluctuates due to influx of Kurkar-type groundwater.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Role of aquifer heterogeneity in fresh groundwater discharge and seawater recycling: An example from the Carmel coast, Israel
Series title:
Journal of Geophysical Research C: Oceans
DOI:
10.1029/2007JC004112
Volume
112
Issue:
C12
Year Published:
2007
Language:
English
Publisher:
Wiley
Contributing office(s):
Coastal and Marine Geology Program
Description:
C12016; 12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research C: Oceans
Number of Pages:
12
Country:
Israel
Other Geospatial:
Carmel Coast, Dor Bay