Determination of mean hydraulic gradient in coastal aquifer under influence of constant head variation in estuarine environmen

• Main Authors: Paulo Cesar Negrão, Sueli Yoshinaga Pereira, Felipe Gasparini, Valter Leite
• Format: Article
• Language: English
• Published: Associação Brasileira de Águas Subterrâneas 2016-10-01
• Series: Revista Águas Subterrâneas
• Subjects: Água subterrânea. Ambiente estuarino. Gradientes hidráulicos. Cargas hidráulicas.
• Online Access: https://aguassubterraneas.abas.org/asubterraneas/article/view/28480
• ISSN: 0101-7004; 2179-9784

In determining the hydraulic gradients of groundwater aquifers in estuarine environment, it is essential to consider the pressure waves resulting from tidal fluctuations and water bodies. The fluctuations of the water level of the Cubatão River and hydraulic head of the shallow aquifer (in 3 levels of depth) in Cubatão, SP, were monitored for 45 days in an adjacent industrial area to the river in order to determine the mean hydraulic head and mean hydraulic gradients by the method proposed by Serfes (1991). The monitoring was continuous and performed in two scenarios: with the remediation system ("Air sparging" technology) activated and deactivated. The results showed the interference of the remediation system and the variations of the tide in hydraulic heads of the nearby wells, and only the variation of the tide in the more distant wells. However, in the upper aquifer the influent condition of the Cubatão river was present in both scenarios. Effluent and influent conditions in the intermediate portion, and predominant effluent of the river in the deep portion were observed. In the intermediate and deep portions of the aquifer, the hydraulic gradients have low values (-0.0027 to 0.0030) so that the analysis of the flow direction have to be careful.