Hydrogeochemical-multivariate analysis of groundwater in the aquifer system of the middle Magdalena valley, Colombia: Regional-scale study

Abstract

To identify the main geochemical processes that determine the chemical compositionand quality of the groundwater of the AquiferSystem of the Middle Valley of Magdalena-Colombia (SAVMM), a database was createdwith the physicochemical characterizationsavailable in the different governmentaland private entities located in the studyarea. In total, 2207 data were collected forthe period between the years 2005 to 2014.For this study, samples that were complete,did not have transcription errors, and hadan analytical error less than or equal to+/- 10% were kept. The number of validsamples was 140. Graphic, hydrochemicaland statistical methods were used to understandgeochemical processes. According tothe analysis of the Piper diagram, it wasobserved that the calcium bicarbonate typeof water is the dominant hydrogeochemicalface throughout the study area, followed bythe sodium bicarbonate and sodium chloridetype. The study was complemented bydoing a multivariate statistical analysis,including a Principal Component Analysis(PCA) and Hierarchical Cluster Analysis(AAJ). With the PCA, three componentsthat represent 59.4% of the variability ofthe data were determined and with the AJJ6 groups were obtained that represent the140 physicochemical characterizations.The geology and hydrogeology of the studyarea was correlated with the results of theACP and the AAJ, thus identifying 3 maingeochemical processes that determine thechemistry of groundwater in the SAVMM:1) Recharge - meteoric water infiltration,2) Dissolution - interaction of water withsilicates and carbonates 3) AnthropogenicAlteration - contamination due to the developmentof industrial activities carried out inthe study area