As águas subterrâneas na porção central da Região Costeira de Aquiraz, Ceará

Abstract

The study area of interest has 57.7 sq. km and it is located on the coastal region of Aquiraz ounty, Ceará State, in the northeastern sector of Fortaleza’s Metropolitan Zone (RMF), roughly 30 km away from the capital city itself. It encompasses basically the county’s main town and the Prainha and Tapera districts. This work’s objectives highlight the role of underground waters under the context of that area’s supply, as well as define its exploitation as regards surface waters of the Catu Lake. For this end to be attained, working procedures were needed that consider the hydrogeological aspects associated with water sampling in specific sites of the aquifer systems and the lake’s. That was meant to get intelligence data which would define the hydrochemical and bacteriological parameters displayed in tables, graphs and diagrams, whereby the qualitative status of those systems’s waters might be established. The overall set of registered points involve 177 tubular and scooped wells wherefrom there were selected the suitable ones for water sampling and analyses referred to the Dunas and Barreiras Aquifers in the dry and post-rainy seasons, with this procedure being the one also adopted in representative points of the lake. The yields in those wells are usually related to the hydrogeological features of the aquifer systems, for which average values of 3.5m-3.h-1 and 2.7 m-3.h-1 were estimated in the Dunas and Barreiras Aquifers respectively. It is thus evident that the sandy-quartz conditions of the former account for a better hydrogeological potency, a fact that could bear upon the underground water reserves. Among the arrived at results, it was found out that underground waters were ionically classified as Chloride Sodic, whereas the pH values show them to be predominantly acid except for a few points with alkaline values during the rainy season. The underground waters possess physicochemical and bacteriological qualities for human supply in 90 per cent of the investigated wells. The lake can play an outstanding role as a water supplier of the study area, as long as it is submitted to routine attendance by an appointed office in addition to its inclusion on a comprehensive management program. As a general consideration of the analyzed data, the results for the estimated parameters are shown to define a sound use of the underground and surface waters, and a relationship between their quality and usage in some districts of Aquiraz county.