Use of hydrogeophysical data to determine the role of faults in the geometry of the Barreiras Aquifer, Brazil

Abstract

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.

Keywords

• neogene fault compartmentalization
• aquifer geometry
• hydrogeophysics
• Barreiras Formation Aquifer
• Brazil