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Neap-spring variations in turbulent kinetic energy (TKE) and discharge from a point-source submarine groundwater discharge (SGD) located within a fringing reef lagoon were investigated through velocity, temperature, salinity and pressure measurements. The principal factors considered for TKE and discharge variations were tides and waves. The field data indicated that TKE and discharge varied between high and low tides, as well as with neap and spring tides. Maximum values were observed during low tides, when the hydrostatic pressure over the spring was minimal, while high tides produced the lowest values. Spring tides produced consistent saltwater intrusion during high tides, while neap tides produced the greatest TKE of the time series. While previous studies have shown higher seepage SGD during spring tides rather than neap, the point-source SGD studied produced greater discharge during neap tides due to the flow reversals observed throughout high tides in spring tides. As the jet discharge intensified (most notably during spring tides), temperatures decreased, while at the same time, salinities increased. The decreasing temperatures suggest aquifer water is exiting the jet, since during this time of year the aquifer is cooler than the lagoon water. While increasing salinities suggest mixing of the aquifer water with sea water. Therefore, it is proposed that the jet conduit is connected to a chamber that is stratified with seawater below aquifer water. As the jet discharge intensifies, mixing between the two layers increases, which is evident in the increasing salinities with decreasing temperatures. While tides were the primary driving force of the discharge, waves also played a role. Wave effects on the discharge was more evident during high tides (than during low tides) when the discharge was weaker, thus more susceptible to wave forcing. |