Bezpośrednie pomiary podmorskiego zasilania wodami podziemnymi Zatoki Puckiej

In situ measurements of submarine groundwater supply from the Puck Lagoon. A b s t r a c t . Fresh water accumulated beneath the sea floor may flow through sediments into the sea water. This process, opposite to infiltration, is called Submarine Groundwater Discharge (SGD). The Southern Baltic Sea coastal zone represents an interesting object of study because its bottom deposits show seepages of fresh groundwater. The study involved Puck Bay and the adjacent coastal belt of the Kashubian Coast plateau. Research of potential outflows of fresh groundwater was done through a thermal imaging of the study area. An articulate thermal anomaly allowed predetermining the location of research points. Groundwater outflows in the seabed were confirmed by measurements of chloride content and electrical conductivity of water samples. The paper presents two new devices: a filtrometer that enables measurement of water filtration intensity during drainage, and a gradientmeter that measures the hydraulic gradient. The use of both devices allows   determination of the in situ hydraulic conductivity. Results of the research have shown relationships between fresh groundwater and the sea-bottom sediments.