Modelagem do avanço da cunha salina em sistema aquífero costeiro

Abstract

Groundwater overexploitation can cause the collapse of coastal aquifers. The goal of this study was to apply a template, the computer code SEAWAT to evaluate the behavior of the salt wedge Coastal Aquifer System, which has studied the case of complex Barreira/Marituba in Part Coast Metropolitan Region of Maceió-AL. In addition they were analyzed physicochemical indexes to characterize the study area and verify the source of salt contamination. The model calibration was performed in two parts. The underground flow calibration obtained a correlation coefficient between calculated hydraulic loads and observed of 0.764 and the calibration concentration of Total Dissolved Solids, which has very close to the salt concentration value, obtained a 0.682 correlation coefficient for the year 2015 . Since then analyzed two different scenarios, which allowed us to verify the effect of groundwater exploitation in the salt wedge for the year 2025. The first considered the existing exploitation by 2015 without pumping increments. As a result, it was found advancing saline wedge area into two areas, an area that suffers decrease, besides the formation of cones with vertical rise of the seawater. In the second scenario were added licenses of water works as well and plus the assumption of 32 new pumping wells installation, according to the city's growth. However, in this case, it was not possible to see variations in the mix zone for the first scenario for the year 2025. The analysis of hydrogeological indices pointed to higher chloride concentrations in the region close to the line of the Atlantic Ocean, with little influence of nitrate and, in general, showed the existence of seawater intrusion.