O papel da infiltração induzida de um rio sobre a zona de captura do poço no estudo da poluição e descontaminação da mesma - caso do rio Piranhas em São Bento-PB.

Abstract

From the data furnished by the CDRM (Mineral Resources Development Company of the Paraiba State) on the two aquifers in the city of Sao Bento. Paraiba situated along the Piranhas River, analysis is made on the same to understand the hidraulics and hidrodynamics of the porous media involved in both. The two aquifers posses similarities in their hydraulic and hydrogeoiogica! characteristics; however their radius of influence, saturated depths and their pumping rates were differing from each ather. The principal reasons for selecting these two areas for the present study are due to the fact that their directions of flow with reference to the axis of the river were different. While area 4 has shown na angle of 45° with the axis of the river, area 3 has na angle of 60° with the direction of flow of the river. Discharges of 20.90, 40.00 and 80.80 nrVhours were considered for analysis and the spatial velocity components were determined using Pinder and Celia's artifice of 1987. considering the discretized quadrilaterals. The Finite Difference Method was used for obtaining the solution of Boussenesq equation for flow in two-dimensions. While treating the contribution of induced infiltrated flow from the aquifer to the pump in both the production wells localized in the aquifer, situated near the wells in question, the model of Wilson e Newson(198S) and Wilson e Annetti(1991) was used. Area 4 displayed nearness to the theory proposed by the above authors, in the sense that it demonstrated the existence of critical flow(Qr). A double-point inflexion was evidenced for for the case where QAV>QC which fact was verified at the adapted discharg of SO.SOnrVhours. four times the value of Q as given by CDRM. The concept of dimensionless discharge. (3 was introduced, the values of which, were observed to lie between 6,36 and 52.5 for the case of Sao Bento. PB. The differences that existed between the two cases{Sao Bento. Paraiba and Albuquerque, New Mexico) were explained in detail. The influence of the contribuition area of induced infiltrated flow over the capture zone was explained in detail. In spite of the inherente differences that existed between the two areas under study, the model served very well as a tool for analysing quantitatively, as also qualitatively the processes involved and threw insight into the parameters that influence the specified zones. Important applications of this study in the determination of aquifers polluted by way of the use of agro-toxics and organochlorides and organochlorides and in cleaning the same by conventional methods such as thebattery of wells were pointed out. This study would help as well in the investigation of the manner in which one should utilize the techniques in diluting aquifers by way of utilization of water from the induced flow from from the river, where the river relatively flows with fresh (pure) water. The study heldy one in planning technical projects of utilization of water resources, where in the present mode! functions as a guide in determmining the environmental impact of the production well situated mear a river. With the help of this model, it is possible to determine the ideal location of a well and ist optimum rate of pumping that corresponds to the demand as needed by the giver Water Supply Project, thus avoiding the entry of polluted waters the public water supply schemes.