MULTIVARIATE STATISTICAL ANALYSIS AND USE OF GEOGRAPHIC INFORMATION SYSTEMS IN RAW WATER QUALITY ASSESSMENT

Abstract

This study aimed to apply a methodology for evaluating raw water qualityand its relationship with land uses and occupations through multivariatestatistical analysis and Geographic Information System. Hydrogenic potential,water temperature, dissolved oxygen, biochemical oxygen demand,chemical oxygen demand, total nitrogen, total phosphorus, and E. coli weremonitored from August 2012 until March 2013. The geoprocessing toolenabled delimiting the contribution areas of each sampling site, as well asthe individual identification of land use of each area. Principal ComponentAnalysis resulted in: domestic sewage, domestic sewage/agriculture, andindustrial discharge. Significant correlations were identified between thevariable urban area and hydrogenionic potential (ρ = 0.446; p = 0.049),dissolved oxygen (ρ = -0.625; p = 0.003), total nitrogen (ρ = 0.649; p = 0.002),and E. coli (ρ = 0.932; p < 0.001). The methodology enabled to identify thecontribution of land use factors as to water quality.