Avaliação do uso e ocupação do solo na qualidade ambiental da água de reservatórios de abastecimento em uma sub-bacia do Rio Piancó-Piranhas-Açu.

Abstract

Water is a natural resource essential for the maintenance of life, and its quality is associated with various processes occurring in a watershed. In this study, the objective was to evaluate the influence of land use and occupation forms on the environmental quality of water in supply reservoirs of the Piancó River watershed. Four reservoirs were studied, for which 05 (five) forms of land use and occupation were analyzed: dense vegetation, open vegetation, exposed soil, surface water bodies and urban areas, besides the elaboration of a pedological map of the area. The water quality parameters were obtained from the Paraíba Water and Sewage Company (CAGEPA): Calcium, Magnesium, Iron, hardness, apparent color, pH, turbidity, total dissolved solids, total coliforms, total oxygen consumed, chlorides and Escherichia coli. To assess correlation, principal component analysis (PCA) was used as a multivariate statistical method. Dense vegetation and open vegetation classes obtained the highest percentages in the reservoirs, which presented significant exposed soil values concentrated in unfavorable regions. The largest extensions of litholic neosol, chromic luvisol and red argissol were identified in all subbasins. Three principal components were selected that explained a total variation of the data of more than 80%. The most significant variables are associated with sediment inputs to the reservoirs, dissolved salts, and organic and microbiological pollution. Factors such as the development of agricultural activities, especially on the banks of the reservoirs, absence of riparian forest and soil type also showed potential interference in the quality of water bodies.