A STUDY OF THE IMPACT OF LAND USE AND OCCUPATION ON BASIN WATER QUALITY THROUGH MULTIVARIATE STATISTICS

ABSTRACT Without effective actions to improve environmental management, water resources tend to become scarce. Thus, this study aimed to understand the processes influencing the physical, chemical, and biological properties of the water due to land uses and occupation in the Ipê stream basin, in Ilha Solteira - SP (Brazil), regarding the dependence of the analyzed variables. Monitoring of chemical, physical, and biological water quality was performed from 2006 to 2011, and the records of land use and occupation in 2011. A factorial multivariate analysis allowed us to understand that the processes in densely populated areas increased degradation of water by the input of organic loads, yet those of farming areas enhanced the degradation of the chemical and physical quality of spring waters. Therefore, installing irrigation systems near populated areas, for crops consumed in natura, may compromise this agricultural activity, as well as the absence of water filtration systems downstream agricultural areas. Furthermore, we concluded that multivariate statistics is a powerful tool to detect these influencing processes in water quality. In this study, this type of analysis played an important role isolating the processes acting on water quality.摘要：若未采取有效措施改善环境管理，水资源极易趋于匮乏。本研究以巴西圣保罗州伊利亚索尔泰拉（Ilha Solteira - SP）的伊佩溪流域（Ipê Stream Basin）为研究对象，旨在解析土地利用与土地占用对水体物理、化学及生物学属性的影响过程，并围绕所分析变量的依存关系开展研究。本研究于2006年至2011年间完成了水质的化学、物理与生物学指标监测，并收集了2011年的流域土地利用与占用数据。经因子多元分析（Factorial Multivariate Analysis）结果显示，人口密集区域的人类活动通过输入有机负荷加剧了水体退化；而农业区域的人类活动则进一步加剧了源头水体的化学与物理质量退化。因此，为种植鲜食作物而在人口密集区域附近布设灌溉系统，以及农业区域下游未配备水体过滤系统，均可能对该农业生产活动造成不利影响。此外，本研究证实多元统计方法是识别水质影响过程的有效工具，此类分析在剥离影响水体质量的各类作用过程中发挥了关键作用。