Estudo estrutural e geoelétrico em aquífero fraturado na região de Caçapava do Sul (RS)

• Autor(a) principal: Oliveira, Mariana Vieira Galvão de [UNESP]
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/204049; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2019-05-14/000914899.pdf
• topic: Geologia estrutural; Aquiferos; Poços; Abastecimento de água; Geomorfologia; Água - Captação; Águas subterrâneas; Geofisica; Granito; Caçapava do Sul (RS)

The inherent structural complexity of fractured rock aquifers, which controls the groundwater accumulation and flow in restricted zones, lead to a high number of non-producing dry wells. The analysis of geomorphological features and indirect investigations allows the identification of favorable targets for groundwater exploitation, representing a rational procedure in villages and small towns far away from urban centers. This work deals with regional and local structural surveys coupled with electrical resistivity tomography data in order to identify favorable targets for groundwater exploitation for urban consumption in a fractured granite located in a small village six kilometers north of Caçapava do Sul city, southern Brazil. The structural control is manifested in the regional landforms and clearly conditions the orientation of main drainages. Based on this structural control, four parallel electrical tomography survey lines were performed in an area of interest for groundwater exploitation, followed by the generation of 2D inversion models and interpolation for the analysis of pseudo 3D models. The contact between the very thin superficial soil (regolith) and the underlying granite massif determines the existence of a regional free aquifer and the probable recharge of the fractured rock aquifer. In the 2D inversion models, abrupt variations of electrical resistivity related to locally recognized vertical fractures occur, although they do not show lateral continuity (out of plane). The analysis of the geophysical maps from 40 meters depth allows the recognition of three alignments of low resistivity (around 500  m) within a granite context where high values predominate (above 15,000  m). These alignments show a triple fracture intersection pattern also recognized in satellite images, which are highly favorable for groundwater accumulation and exploitation