Geochemistry of the surface and ground waters of the upper bassin of the river Llobregat

Abstract

In this work the main geochemical characteristics of the surface and ground waters of the Upper basin of the River Llobregat are described and, discussed. The water samples analysed reveal sharply contrasting characteristics. In both the Fonts del Llobregat and River Bastareny catchments, calcium bicarbonated waters with a low mineral content clearly predominate. However, in the catchment of the River Arija, although the waters of the upper course and the main tributaries are also calcium bicarbonated, it is worth noting that at the confluence with the River Llobregat calcium sulphated water is found. The catchment of the River Saldes shows a greater heterogeneity, with calcium bicarbonated, sodium chloridized and calcium sulphated waters, and thus at the confluence with the River Llobregat the water is sodium-calcium bicarbonated-sulphated. Principal components analysis enables us to arrive at a synthesis which clearly explains these characteristics. These results are fundamentally interpreted on the basis of the lithologies drained by the different watercourses.