Anuário do Instituto de Geociências (Aug 2007)
Fatores Hidrogeológicos no Estudo da Intrusão Salina em Aqüíferos Costeiros da Região Litorânea do Município de Maricá - RJ.
Abstract
The oceanic area of Maricá, in the east coast of the Rio de Janeiro State, relies on groundwater as its mainsource of fresh water supply along with the use of water tank trucks. With the increasing demand of water resources,water supply and contamination problems are foreseen, and sea water intrusion phenomenon is also expected in theseaquifers. The groundwater resource of the target area has been submitted to quality degradation due to the advanceof the saline wedge, the excess of pumping without control and also the pollution of organic origin. Considering thissituation, the study aims to contribute to a better knowledge of the hydrogeological characteristics in order to assist theaquifer management of the coastal area under study. The area comprises a granular aquifer and local geology consistsbasically of marine and fluvio-marine Quaternary sandbar deposits, overlying a crystalline basement of variabledepth. The study included the evaluation of previously existing hydrological data in the area, rainfall data, and a fieldsurvey in 41 wells, with measurements of hydrodynamic and physical-chemical parameters (temperature, electricconductivity, hydraulic head). Furthermore, an automatic instrumentation was installed to evaluate the response of theaquifer to recharge. Results indicate that aquifer salinity levels tend to rise in the SE portion, and also, apparently, therehas been an increase in aquifer salinization in recent years, demanding urgent management actions. The automaticinstrumentation shows that Maricá coastal aquifer gives a rapid response to seasonal factors and climate, showing somevulnerability, but also rapid recharge and dilution capacity.
