Anàlisis de la relació llacuna-aqüífer de tres basses ubicades al Baix Ter

Abstract

Coastal lagoons are masses of water that stand out for their ecosystemic importance and for their great biodiversity, but also for their vulnerability to impacts. These lagoons are characterized by their relationship with maritime waters, as they are a transitional element between terrestrial space and the sea. However, this work has focused on studying the relationship between the lagoon and the groundwater. The study has focused on the Baix Ter area, specifically on the Pletera natural area. La Pletera is a system of restored wetlands, which suffered strong human pressure during the eighties, the result of an urban project. The entire coastal lagoon system was restored through two LIFE projects. For this study, three of the six gaps that make up this network have been chosen. The lagoons studied are Fra Ramon (FRA) of natural origin, M03 and L04 both of artificial origin, created within the framework of the two LIFE projects. The aim of this work is to determine its relationship with the aquifer, as well as the hydrogeological state. To achieve the objectives of the study, methods have been carried out that evaluate the surface-subterranean relationship of the aquifer. The methods used have been those of mass balances, concentration monitoring, mathematical models and heat tracers. Regarding the results, it has been determined through meteorological and piezometric data that the study area suffers from very significant water stress at the time of analysis. It has also been seen through the evolution of the lagoons that the water in the lagoons is maintained mainly by underground contributions throughout the year, except when there are periods of precipitation. In addition, it has been determined that at the depth of Fra Ramon (FRA) stratification occurs during the autumn and winter weather seasons. Other results show the evolution of ions (Cland SO42-), alkalinity, nutrients (TN, PT, TOC and PT/PO43-), which have reaffirmed the stratification in Fra Ramon (FRA). The isotopes (δ18O and δD) have shown that all the lakes suffer the same evaporation and that in the summer months or close to them, evaporation is much more accentuated, on the other hand, in the winter or autumn months, it is less. Finally, with principal component analysis (PCA), some of the observed results have been confirmed. In general, this work has made it possible to determine that the lagoons receive an underground contribution most of the year, except when precipitation occurs, that the situation can be reversed. In addition, it has been established that the lagoon with the most salinity is M03, and the one with the least salinity is L04

Coastal lagoons are masses of water that stand out for their ecosystemic importance and for their great biodiversity, but also for their vulnerability to impacts. These lagoons are characterized by their relationship with maritime waters, as they are a transitional element between terrestrial space and the sea. However, this work has focused on studying the relationship between the lagoon and the groundwater. The study has focused on the Baix Ter area, specifically on the Pletera natural area. La Pletera is a system of restored wetlands, which suffered strong human pressure during the eighties, the result of an urban project. The entire coastal lagoon system was restored through two LIFE projects. For this study, three of the six gaps that make up this network have been chosen. The lagoons studied are Fra Ramon (FRA) of natural origin, M03 and L04 both of artificial origin, created within the framework of the two LIFE projects. The aim of this work is to determine its relationship with the aquifer, as well as the hydrogeological state. To achieve the objectives of the study, methods have been carried out that evaluate the surface-subterranean relationship of the aquifer. The methods used have been those of mass balances, concentration monitoring, mathematical models and heat tracers. Regarding the results, it has been determined through meteorological and piezometric data that the study area suffers from very significant water stress at the time of analysis. It has also been seen through the evolution of the lagoons that the water in the lagoons is maintained mainly by underground contributions throughout the year, except when there are periods of precipitation. In addition, it has been determined that at the depth of Fra Ramon (FRA) stratification occurs during the autumn and winter weather seasons. Other results show the evolution of ions (Cland SO42-), alkalinity, nutrients (TN, PT, TOC and PT/PO43-), which have reaffirmed the stratification in Fra Ramon (FRA). The isotopes (δ18O and δD) have shown that all the lakes suffer the same evaporation and that in the summer months or close to them, evaporation is much more accentuated, on the other hand, in the winter or autumn months, it is less. Finally, with principal component analysis (PCA), some of the observed results have been confirmed. In general, this work has made it possible to determine that the lagoons receive an underground contribution most of the year, except when precipitation occurs, that the situation can be reversed. In addition, it has been established that the lagoon with the most salinity is M03, and the one with the least salinity is L04