Establiment de la recta altitudinal i meteòrica del Montseny-Guilleries en base a dades hidroquímiques i isotòpiques de fonts

Abstract

The following document is a chemical and isotopic study about the water from the springs in Sant Hilari de Sacalm (Province of Girona). It focuses on the isotopes 𝛿18O and 𝛿2H, from which has been defined and analysed the water meteoric line for this area. The stable isotopes present in water might provide us with information about the processes to which it has been subjected. On this project, we focus specifically on 𝛿18O isotope which depending on its proportion with deuterium may be related with the precipitation height due to most of the sampled springs, are representative of local recharge in known heights using springs with an altitudinal recharge area already defined. With this method, we can plot a regression line model and use it to identify the recharge height of a single sample. The study area is located in the Guilleries massif where the hydrogeological characteristics allow a high number of natural water springs. Therefore through the data provided by the University of Girona sampled during 2017 and 201, has been described the different kind of water depending on the hydrogeology and their chemical skills, and has been defined the most representative meteoric water line and altitudinal line. Using geographical information Systems, have been located and defined the recharge area for each fountain and have been extracted the significative heights for the correlation with the isotopes. Afterwards each fountain has been classified depending on its chemicals and related with the geology and anthropic uses of the surroundings. Finally the meteoric water line has been defined, looking for the most representative, excluding the springs with unusual data or the ones put down to processes that may modify the real levels of isotopes. Such as due to a high rate of evaporation or the sulfur springs. To conclude the project, we have compared Sant Hilari’s meteoric water line and altitudinal line with other data from the Montseny massif provided by the University of Barcelona to plot a more general model and it has been tested with sample from wells belonging to the deep aquifer located in the areas of La Selva and Osona’s plain