Assessing the salinization mechanisms of coastal brackish springs

Brackish springs have been extensively reported in Mediterranean coastal carbonate formations. The phenomenon is puzzling because these may discharge high flow rates with significant salinities at elevations of several meters above sea level. Although studied for millennia (since the ancient Greeks), controversy persists. In essence, they are typically assumed to consist a karstic conduit bringing fresh groundwater that meets saltwater branching point, where brackish mixture flows up spring mouth. Here, we analyze hydraulics system two simple cases, depending on whether seawater occurs through an open or porous aquifer. To this end, derive equations governing variable-density turbulent conduits. These turn out be similar traditional ones, except (1) Bernouilli’s head (energy per unit weight) substituted by energy volume, and (2) not potential, as path dependent term needs added. We solve obtain characteristic functions relating concentration. specific every representative karst salinization mechanism. They allow us show salinity mostly controlled weight water column flowing towards mouth (for low rates) dissipation rates). When concentration rate data available, it possible characterize: resistance upwards from response rate; depth point discharges; (3) hydraulic slope vs. discharges. patterns compared field three different springs, which yields insights conceptual model particular spring.