Abstract Saturated thickness is a vital parameter in the assessment of hydrogeological reserves. By considering thickness variations associated with faults, the present study aimed to evaluate the water reserves of an unconfined aquifer. The study area was the Barreiras Aquifer in the lower course of the Maxaranguape River in Brazil. The methodology involved morphotectonic and lithostratigraphic analysis, well profile correlation, and hydrogeological and geoelectrical analysis (vertical electrical sounding, VES). The morphotectonic analysis employed topographical (Shuttle Radar Topography Mission) and hydrographical data to support the structural characterization, considering the lack of outcrops with specific features in the area. The results of these assessments enabled the creation of a morphotectonic lineament map, highlighting the prevailing NE and NW directions. The hydrogeophysical cross sections obtained from geoelectrical inverse models and well data reveal saturated thickness values ranging from 19 to 66 m, featuring some lineaments as faults. The hydrogeological reserve was calculated based on 18 subareas associated with blocks resulting from structural compartmentalization. Based on an area of approximately 250 km2, the average saturated thickness for each subarea, and an average effective porosity of 7.6%, the saturated reserve is estimated to be 8.7 × 108 m3.

Abstract Characterizing the geometry of an aquifer is fundamental for determining the locations of more productive wells. Commonly, flow and hydraulic parameters, such as transmissivity, are related to the thickness of the aquifer, which emphasizes the importance of regional hydrogeophysical characterization. Shuttle radar imagery, well profiles and geoelectric models (thickness x resistivity) from sixteen soundings were used to identify Neogene faults in the Barreiras Aquifer in the Catu River basin, northeastern Brazil. The joint analysis of the geomorphological data enabled the development of a synthesis map characterizing morphotectonic alignments that are mainly N50º-60ºE and N40º-60ºW trending. A number of these alignments were interpreted as faults based on 10 to 44 throws that were identified in the hydrogeophysical cross-sections. The highest values were located in the northeastern portion of the area, suggesting the direct association between saturated thickness and Neogene faults. Additionally, the geoelectric and hydraulic head data of the aquifer allowed the identification of the most promising sites for future water exploitation in the northeastern portion of the study area with transverse resistances equal to or greater than 40,000 Ohm.m. The geometry and transmissivity of the Barreiras Aquifer indicate that porous aquifers in structural highs could be controlled by faults.