Aplicação da análise estatística multivariada no estudo da qualidade da água subterrânea

Abstract

Resumo -A explotação racional e sustentável dos recursos hídricos se torna atualmente cada vez mais importante, tendo em vista que a sociedade convive com diversos e grandes desafios, principalmente aqueles referentes a crescente demanda de água em quantidade e qualidade como consequência do aumento da taxa de crescimento populacional, implantação de indústrias, acréscimo da pegada hídrica, produção de alimentos e, enfim, desenvolvimento, especialmente em áreas de escassez, como em regiões áridas e semiáridas, como no caso específico da área de estudo. Como a utilização das águas subterrâneas para fins diversos também está condicionada a qualidade, neste trabalho desenvolveu-se uma metodologia utilizando a técnica da análise fatorial, associada a análise de agrupamento multivariada, objetivando dar suporte à gestão hidroqualitativa. Foram identificadas similaridades entre atributos físico-químicos capazes de explicar possíveis processos responsáveis pela qualidade das águas, tomando como estudo de caso o município de Fortaleza, Ceará. A análise fatorial aplicada a atributos físico-químicos identificou três componentes responsáveis por aproximadamente 86% da variância total. O primeiro como indicador de salinidade e poluição (K Abstract -The rational and sustainable exploitation of water resources is becoming increasingly important, given that society coexists with several major challenges, especially those related to the increasing demand for water in quantity and quality as a consequence of the increase in the rate of growth population growth, the implantation of industries, the increase of the water footprint, food production, and finally, development, especially in areas of scarcity, as in arid and semi-arid regions, as in the case study area. As the use of groundwater for various purposes is also subject to quality, this work developed a methodology using the technique of factor analysis, coupled with multivariate cluster analysis, aiming to support the qualitative management. Similarities were found between physical and chemical properties capable of explaining possible processes responsible for water quality, taking as a case study the city of Fortaleza, Ceará. Factor analysis applied to physical and chemical properties identified three components account for approximately 86% of the total variance. The first indicator as salinity and pollution (K

Multivariate statistical analysis applied to the evaluation of groundwater quality in the central-southern portion of the state of Bahia - Brazil

“…This clustering criterion uses the total sum of the squared values of each object's deviations in relation to the mean value of the group where it was inserted. This criterion was chosen based on its frequent application in studies on water quality (Vega et al, 1998;Andrade et al, 2008;Fernandes et al, 2010;Salgado et al, 2011;Gomes and Cavalcante, 2017).…”

“…The multivariate analysis helps in the definition of which variables are more important for water management, assisting in the selection of variables using more objective criteria. This type of statistical analysis is an effective tool in the qualitative evaluation of waters (Vidal and Kiang, 2002;Brito et al, 2006;Cloutier et al, 2008;Palácio, 2009;Fernandes et al, 2010;González et al, 2011;Finkler et al, 2015;Gomes and Cavalcante, 2017).…”

Analysis of the Levels of Alteration of Aquifers Caused by the Installation of Wind Farms on Dunes on the Coast of Ceará, Brazil

“…In the group analysis, groups are formed from measures of distance between observations in each factor. In this step, Ward's method was used as the hierarchical grouping criterion and the similarity measure used was the squared Euclidean distance, which is often used in water quality studies (Yidana et al, 2008;Salgado et al, 2011;Gomes and Cavalcante, 2017). The assessment of the suitability of groundwater for human consumption was carried out according to the potability standard of the Ministry of Health Ordinance N°.…”

“…They are generally overlying the Barreiras Formation and the regional average static level is 6.0 m and the average flow rate obtained from shallow tubular wells (depth less than 20m) is 6.0 m³/h. The Barreiras Aquifer has a large facies variation, sediment thickness between 20.0 to 60.0 m and differentiated silica-clay-sandy intercalations that lead to different hydrodynamic parameters, both vertically and horizontally, with the sandy levels representing the main ones in terms of aquifer vocation (Cavalcante, 1998 apud Gomes and Cavalcante, 2017).…”

“…These methods identify the most significant variables in natural and / or anthropic terms and have been employed in different areas. In the context of groundwater resources, Brito et al (2006), Cloutier et al (2008), Salgado et al (2011), and Gomes and Cavalcante (2017), among others, have used this statistical tool to support the monitoring and qualitative management of groundwater, especially in regions of high socio-environmental vulnerability, such as the area surrounding the wind farm on Xavier Beach and in the localities of Ziu, Tapuiu and Montevideo, all belonging to the district of Amarelas, Camocim, Ceará.…”