Submarine groundwater discharge measured by seepage meters in sicilian coastal waters

Seepage measurements of submarine groundwater discharge (SGD) were carried out in March 2002 in the Donnalucata boat basin in the southeastern Sicily. SGD rates measured by manual seepage meters ranged from 5.5 to 19.3 L/min/m (with an average of 12.1 L/min/m), which was 0.6 and 5.9 times the SGD determined in Florida and Perth, respectively. The spatial distribution of SGD was found to be highly variable along ∼300 m long coast area. Semi-diurnal SGD variations which anti-correlated with tide were found using newly developed automated seepage meters that can provide continuous SGD data with high resolution. These variations may be attributed to the tidal effect, when a greater hydraulic gradient, observed at low tide, moves groundwater from land to the ocean, and an opposite effect is observed at high tide.