Effects of Groundwater Inputs to the Hydraulic Circulation, Water Residence Time, and Salinity in a Moroccan Atlantic Lagoon

• Published in: Journal of marine science and engineering 2022-01, Vol.10 (1), p.69
• Main Authors: Elyaagoubi, Soukaina, Umgiesser, Georg, Maanan, Mehdi, Maicu, Francesco, Mėžinė, Jovita, Hilmi, Karim, Razinkovas-Baziukas, Artūras
• Format: Article
• Language: English
• Subjects: Aquaculture; Bathymetry; Benthos; Biogeochemistry; Boundary conditions; coastal ecosystem; Coasts; Distribution; Ecosystem services; Finite element method; finite element modeling; Fisheries; Fluid mechanics; Groundwater; Groundwater discharge; Hydraulics; Hydrodynamics; Lagoons; Local population; Macroinvertebrates; Marine molluscs; Mathematical analysis; Mathematical models; Meteorological data; physical parameters; Protected areas; Residence time; Residence time distribution; Salinity; Salinity effects; SGD inputs; SHYFEM; Small-scale fisheries; Solar radiation; Spatial distribution; Water circulation; Water levels; Water quality; Water temperature; Zoobenthos
• ISSN: 2077-1312; 2077-1312
• DOI: 10.3390/jmse10010069

The finite element model SHYFEM was used to study the hydrodynamics and variability of water level, salinity, temperature, and water residence time (WRT) in the Oualidia lagoon located on the Moroccan Atlantic coast. The lagoon hosts a RAMSAR convention-protected area and also offers a set of valuable ecosystem services providing the source of income for the local population. To assess the effects of submarine groundwater discharge (SGD) inputs in the study area, four simulations were set up using different SGD inputs estimates in addition to tidal forcing, bathymetry, meteorological data including solar radiation, rain, and wind, in addition to boundary conditions in the Atlantic such as salinity, water level, and water temperature. The model was calibrated and validated using hydrodynamic measurements of previous studies in 2012 and 2013. The final results from the model are in good agreement with measured data. The simulation with SGD input ~0.05 m3 s−1 produced salinity values closest to the observed ones. Calculated spatial distribution of WRT, temperature, and salinity reduced to coordinates in two PCA axes is consistent with lagoon zones developed earlier using the benthic macroinvertebrate distribution. The calculated spatial distribution of WRT allowed us to evaluate the placement of oyster aquaculture farms and small-scale fisheries in relation to water quality issues existing in the lagoon.