A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007, 125-133.
Temporal variability of submarine groundwater discharge: assessments via radon and seep meters, the southern Carmel Coast, Israel
Yishai Weinstein1, Yehuda Shalem1,2, William C. Burnett3, Peter W. Swarzenski4 & Barak Herut2
1 Department of Geography and Environment, Bar-Ilan University, Ramat-Gan 52900, Israel
2 Israel Oceanographic and Limnological Research, Haifa 31080, Israel
3 Department of Oceanography, Florida State University, Tallahassee, Florida 32306, USA
4 US Geological Survey, St Petersburg, Florida 33701, USA
Abstract Seep meter data from Dor Bay, Israel, showed a steady decrease in submarine groundwater discharge (SGD) rates between March and July 2006 (averages of 34, 10.4 and 1.5 cm d-1 in March, May and July, respectively), while estimates based on radon time series showed remarkably uniform averages (8 cm d-1). The May seep meter data show a rough positive correlation with sea level, unlike the negative correlation shown by the Rn-calculated rates. Smaller-size meters, deployed in July adjacent to the regular-size ones, showed significantly higher rates (10 cm d-1), which negatively correlated with salinity. It is suggested that the decreased rates documented by the seep meters are the result of an increased shallow seawater recharge in the bay (due to decreasing hydraulic gradients). This is not captured by the radon, since recharging water is radon-poor. The positive correlation of discharge with sea level is due to increased seawater recycling in times of high sea stand.
Key words submarine groundwater discharge; radon; seep meter; seawater recycling; electrical resistivity