A dynamic model to simulate water level and salinity in a Mediterranean coastal lagoon

Abstract

In this study, a dynamic model for a Mediterranean coastal lagoon (Albufera des Grau, Menorca, Western Mediterranean) is presented. A simple model with limited data requirements was constructed to simulate the daily variations in water level (<em>WL</em>) and water salinity (<em>S</em>) in the lagoon. Both parameters constitute the main descriptors of the lagoon hydrology and have substantial ecological significance. The model consisted of three coupled submodels: a submodel for the water balance in the watershed, a submodel for the water balance in the lagoon and a submodel for the salt mass balance in the lagoon. The results of the study revealed that the model simulated the temporal dynamics of both <em>WL</em> and <em>S</em> with reasonable accuracy (mean error of 7.6 cm and 2.8 g L⁻¹ for <em>WL</em> and <em>S</em>, respectively). The model made it possible to determine the annual water and salt budgets, which were characterised by intense inter-annual variability. A simulation carried out for the last 30 years accurately predicted the long-term range of variation of salinity, and even severe hyperhaline periods were correctly simulated. The model is believed to be a useful tool in predicting the occurrence of ecologically degraded situations and could contribute to future biogeochemical studies.