HYDROCHEMICAL CHARACTERIZATION OF GROUNDWATER MIXING IN SEDIMENTARY AND METAMORPHIC RESERVOIRS WITH COMBINED USE OF PIPER PRINCIPLE AND FACTOR-ANALYSIS

A procedure to interpret hydrochemical data based on a combined use of factor analysis (correspondence analysis) and Piper's classification principle is outlined and applied to the study of a multi-reservoir hydrothermal system (Allevard) located in the French Western Alps. Values of physico-chemical parameters determined on 95 water samples related to a single point (Allevard Spring) and gathered from previous studies extending over several decades were submitted to this procedure. The approach proved successful in differentiating groundwater masses of different hydrogeological origin which mix and discharge at the outlet of the system. The statistical analysis, supported by structural and isotopic information, allowed formulation of a flow and mixing model in agreement with geological evidence and comprising near-surface, subsurface and deep subsystems. © 1990.