Modeling Seasonal Salinity Dynamics in the Navío Quebrado Coastal Lagoon, Colombia

Navío Quebrado Lagoon is a shallow coastal waterbody connected to the Caribbean Sea through an inlet, and it lies within Colombia’s protected-area system, specifically, the Los Flamencos Flora and Fauna Sanctuary. In this work we set up the Environmental Fluid Dynamics Code Plus (EFDC+) model to examine salinity behavior across 2024, combining field measurements with hydrological, meteorological, and tidal datasets obtained from national monitoring agencies. Model calibration used RMSE, the Nash–Sutcliffe efficiency (NSE), and R2, and the fit was consistent for both water levels and salinity. To isolate the role of lagoon–sea connectivity, we compared a reference run (real inlet dynamics) against three scenarios: (E1) the inlet kept permanently open, (E2) the inlet kept permanently closed, and (E3) a second inlet kept permanently open while the original inlet maintained its observed opening/closure behavior. Model results show that under the reference condition, salinity presented strong spatial and seasonal changes, with 164 consecutive days of critical hypersalinity events, with an annual range of 0 to 200 ppt. Scenarios E1 and E3 produced more favorable conditions by keeping lagoon salinity within 0–66.9 ppt and 0–44.5 ppt, respectively. In contrast, E2 substantially altered hydrologic conditions and significantly reduced lagoon water volume and salinity variability.