Aplicació del model GLM (General Lake Model) per a l'estudi del règim hidrològic de les llacunes litorals de La Pletera

Abstract

Coastal wetlands are one of the most affected ecosystems by human activity, with a high degradation of their ecological status and, the few remaining are surrounded by buildings. It is one of the richest and most productive ecosystems in the world that maintains a certain balance with the entrances of the sea. The studied area is the Pletera, a wetland system located in the Baix Empordà marsh, close to the mouth of the Ter river, which has recently been de-urbanized thanks to the Life Pletera project, which aims to recover the complete ecological functionality of this zone. Until now, the hypothesis has always been that these loopholes depend only on surface inlets of the sea and precipitation, leaving aside the role of the aquifer. In this work, the hydrological regime and the salinity of three lagoons of La Pletera (Life A, B and C) were analyzed during the period between December 2014 and September 2017. The General Lake Model program, with open source software developed by Hipsey et al., (2014), is a one-dimensional model of equilibrium and stratification of a body of water in line with experimental and meteorological data. Through this program, we have determined for each lagoon, the temporary evolution of the salinity and the underground inflows and outflows, and to elaborate a balance of mass that has allowed to calculate the rates of evaporation and other parameters that affect the lagoons. Moreover, thanks to the meteorological data, the oscillations of the levels of each lagoon have been studied with the sea level and sea storms, among others. The results show that lagoons depend on the underground inputs to maintain their level during the driest and warmest period of the year and its salinity is marked by evaporation, underground inputs and surface sea inlets. In addition, it has been determined that the evaporation of each lagoon depends on its morphology. Based on these results, the present study aims to be another proof of the importance of hydraulic connectivity between the marshes and their underlying aquifers and that requires the commitment of all to preserve it