Limnology of mountains rivers and transport of phosphorus and nitrogen to an enriched reservoir (Cordoba, Argentina)

Abstract

The San Roque Reservoir is the principal water resource for drinking water in Córdoba City, Argentina. The basin is located in the central semi-arid region of the country, which has a mean annual precipitation of 650 mm, concentrated in spring and summer. It comprises a mountainous area formed by crystalline basement, igneous granitic rocks and gneiss. They include rocky soil (lithosols) and alluvial sediments. The landscape is mainly composed of two different environmental units, grassland and dry xerophytic bush, with some areas partially modified by rural activities. Tourism represents the main activity within the area, followed by extensive cattle breeding. Several cities are located within the basin. Carlos Paz, located at the lake shore, is the largest, with 50,000 permanent inhabitants, and increasing to 90,000 inhabitants in summer. None of theses cities have sewage treatment plants. Consequently, during the past few years, the reservoir has been showing strong signs of eutrophication. The purpose of the present study was to estimate the P and N loadings and to assess their relative importance in determining the trophic status of the lake.