Title : Modeling hypersalinization processes in tropical coastal lagoons and their morphodynamic implications in Navío Quebrado Lagoon, Colombia
Abstract:
Coastal lagoons are productive transitional ecosystems, yet highly sensitive to environmental variability. In the Colombian Caribbean, Navío Quebrado Lagoon, located within the Los Flamencos Flora and Fauna Sanctuary, is a shallow system intermittently connected to the sea through a lagoon inlet. In this ecosystem, salinity largely determines the ecological structure; however, its equilibrium is increasingly threatened by hypersalinization processes associated with climate change and local pressures.
Although previous studies have addressed regional hydrodynamics, limited knowledge persists regarding the mechanisms controlling salinity dynamics, particularly under changes in lagoon–sea connectivity. To address this gap, the modelling system EFDC+ Explorer was implemented to analyze the spatial and seasonal variability of salinity during 2024, integrating field measurements and secondary information. Model calibration assessed using RMSE, Nash–Sutcliffe efficiency, and R², showed a consistent fit for both water levels and salinity.
A reference simulation, based on the observed opening and closing dynamics of the inlet, was compared with three scenarios: E1, a permanently open inlet; E2, a permanently closed inlet; and E3, the permanent opening of a second inlet while the original inlet retained its observed behavior. The results indicate that the alternation between inlet opening and closure, together with evaporation, controls the salinity regime. Under the reference condition, the model reproduced critical hypersalinity events over 164 days, with salinity ranging from 0 to 200 ppt. In contrast, E1 and E3 reduced salinity to ranges of 0 – 66.9 ppt and 0 – 44.5 ppt, respectively, whereas E2 deteriorated the hydrological and water quality conditions of the system.
This study provides a tool to assess the hydroenvironmental vulnerability of the lagoon and to support management and conservation strategies for tropical coastal systems exposed to climate change and morphological transformations.
