This study had the objective of identifying the variables responsible for the variability of underground water quality from the Salitre river watershed in the state of Bahia, Brazil, as well as knowing sources which show similar characteristics, aiming at contributing to monitoring measures and management of water quality of the watershed. For that, multivariate analysis techniques were used such as factorial analysis by main components and grouping. The factorial analysis allowed grouping the variables into three main factors which explained 86.99%; 72.08% and 68.33% of the total variance in the following periods: 1984 and 2001, in raining season and drought season, respectively. The prioritized variables are related to water salinity. So, improving measurement of water quality in this watershed must necessarily prioritize water salinity, which is associated with its geology. The water sources were classified into three classes and C1 grouped the best quality sources, totalizing 25.0%; 74.3% and 61.7% of the water sources which mean values of total dissolved solids varying from 199.0 mg L-1, in 1984, to 724.86 and 650.34 mg L-1, in the two seasons of 2001, respectively. Most of the sources classified in 1984 as C1 remained like that in 2001.
environmental impacts; factorial analysis; cluster
