Evaluation of the salt accumulation process during inundation in water resource of Contas river basin (Bahia-Brazil) applying principal component analysis

摘要

The high salinization in some reservoirs of the Contas river basin (Bahia-Brazil) has been erroneously attributed only to concentration by evaporation. However, recent studies of this basin have shown that in period of intense rainfalls, occur an increase of the saline concentration in the flowing rivers of the reservoirs. The application of statistical methods (cluster and principal components analysis) have shown that this fact can be attributed to the discharge of saline waters from the small reservoirs of every drained area, provoked by inundation, is also an important factor in the salinization process. Thus the study of the geochemical variables: Na~+ , K~+, Ca~(2+), Mg~(2+), Cl~-, SO_4~(2-) and CO_3~(2-), showed one group formed by Na~+ and Cl~-, attributed to the discharge of saline water provoked by inundation from a small reservoir, and a second group constituted by Ca~(2+) , Mg~(2+), K~+ and SO_4~(2-), due to an increase provoked by the evaporation in the salinization process.