Qualidade das águas em resposta aos efeitos do uso da terra na área de influência direta de reservatório pelo emprego da análise multivariada

Abstract

The process of water degradation in a reservoir is directly related to the exchange of organic and inorganic matter between the river, the plain and its basin, whose effects are the alteration of the abiotic and biotic patterns and processes of aquatic ecosystems. The present work aimed to apply the “PCA - Principal Components Analysis” for analise the interrelationship between the types of land use and land cover related with the water quality of “Barra dos Coqueiros Reservoir”. The samples of water were collected in July 2016, dry season, at 39 different points of the reservoir. The Principal Component Analysis Model was defined using only 18 of the 36 variables on physical, chemical and biological characteristics of water. The results obtained by the “PCA” demonstrated that the first axes explain 42,60% of the total variation of the physical-chemical characteristics of the water in the reservoir. The plot of PCA show a separation between the points that are influenced by the urbanized area and agriculture / pastures. The first axis of the “PCA” is under the influence of organic pollution and ions dissolved in water. The second axis of the “PCA” indicates a component associated with the distribution of solids inside the reservoir. The method employed using “PCA” demonstrate a great value for the explanation of the influence of land use and cover on the water quality of reservoir. Keywords: PCA, multivariate statistical, reservoir, physical-chemical variables of water.