Estudio hidrogeoquímico de la cuenca del Río Adra

Abstract

The methodological approach of this study uses both conventional and multivariate procedures. The latter includes Cluster Analysis, for grouping water samples of similar chemistry, and Factor Analysis that shows the relative importance of the main hydrochemical processes. The results so obtained give us in addition some new insights about the aquifers and the groundwater flow systems involved. From a hydrological standpoint, although located in the semiarid SE Spain, the studied basin keeps a humid e1imate in its head area. The main aquifers are triassic carbonates; they show differents hydrochemical features according their lithology and the particular flow systems, and range from bicarbonate waters with less than 400 mg/l of TDS, to chloride-sulphate and 1.500 mg/l. The latter type are responsible for the streamwater quality in its final path and, as a consequence of this, for the coastal detritic aquifer groundwater chemistry too. The subsurface flow waters of the metamorphic head area have less than 100 mg/l of TDS, acid character and Cree carbonic gas. An old recharge practice in the region -known as «careos»,- can modify the original chemistry of these waters. Other possible change may appear locally as a consequence of the mixing with deep-flow waters, that rise in the vicinity of some important fracture traces.