Numerical analysis of hydrogeochemical data: a case study (Alto Guadalentin, southeast Spain)

This study examines the spatial variability of the factors obtained from th e application of correspondence analysis to a hydrogeochemical data set. Th e goal was to synthesize the hydrogeochemical information using this multiv ariate statistical technique, by setting a series of factors which clarifie d the main properties of one aquifer. Then, a geostatistical framework to o btain a probabilistic assessment of groundwater quality was established. Ex perimental and theoretical semivariograms of the selected factors, consider ed as regionalized variables, were computed. These variographic information and factor values in the experimental sites were used in the ordinary krig ing, which provides unbiased and linear estimates of the regionalized varia bles. These estimates were used to compile maps of the chosen factors, whic h explain their spatial distribution. The selected case study was the alluvial aquifer of Alto Guadalentin which is situated in southeast Spain, in the Internal Zones of Betic Cordilleras. These waters are chiefly SO4 and Cl types, but HCO3 facies are common in t he central sector of the basin. High temperature, acid pH, problems of over exploitation and pollution by CO2-gas characterise these waters. Available groundwater quality monitoring data were used to calibrate the numerical mo del. The present study focused on setting the main physical and chemical at tributes and establishing the spatial pattern of groundwater quality and th e temporal changes in this pattern. (C) 2000 Elsevier Science Ltd. All righ ts reserved.