Applied Geophysics: geoelectrical methods in hydrogeology
Antonio Celso de Oliveira Braga
Recent water crises in several regions of Brazil have highlighted the importance of underground sources such as aquifers. However, how to find the right place to drill a well? How to investigate the quality of water hidden underground? And how to protect these natural reserves from contamination?
The book Applied Geophysics: geoelectrical methods in hydrogeology points out tools for the detection of groundwater and also contaminants using electrical probing techniques and electrical profiling. Bringing together theoretical knowledge to extremely practical issues, the book presents field arrangements and provides guidelines for data collection and interpretation, and also discusses the solutions applied in historical cases.
Studies have been carried out to drill wells in different types of aquifers (granular, karst and coastal, for example) and several investigations for the detection of plumes of contamination from landfills, cemeteries, gasoline and diesel oil leaks, chemical contamination, among other factors that can make these precious resources vulnerable.
A key element in the management and planning of abstraction aiming to supply, monitoring and remediation of contaminated areas, geoelectrical methods in hydrogeology are discussed in this work both in its theoretical aspects and in its practical applications, offering guidelines on the collection and interpretation of data, case studies and assistance in choosing the most appropriate methodology.
- Original title
- Geofísica Aplicada: métodos geoelétricos em hidrogeologia
- Year of publication
About the authors
Antonio Celso de Oliveira Braga
Antonio Celso de Oliveira Braga is a geologist, PhD in Geosciences and Environment and a “livre-docente” professor from São Paulo State University. He worked as a geophysicist at the Institute for Technological Research (IPT)/ Applied Geophysics Group from 1978 to 1995. He is currently an Adjunct Professor, focusing on Hydrology and Geophysics applied to hydrogeology (geoelectrical methods) and works in graduate and postgraduate programs.
The access to water resources requires the attention of public managers in the face of the increase in demand and the decrease in supply in terms of quality, accessibility and flows provided by surface water resources. The underground water resource is an alternative considered in many cases, preferably where the availability of the superficial resource is scarce, complementing or even replacing this form of abstraction, besides being relevant in economic terms. Geophysics, when applied in studies involving groundwater, represents a fundamental subsidy in the management and planning of abstraction for the supply, monitoring and remediation of contaminated areas. The use of geoelectric methods is a possibility in this context, considering the sensitivity of indirect measurement of alterable physical parameters in the presence of pollutants in soils and groundwater, and the wide coverage for space research in a fast way at a relatively low cost when compared to traditional direct research techniques. In addition, geoelectrical methods assist in the indication of favorable areas of promising aquifers for the abstraction of groundwater.
This book aims to fill a gap in the Brazilian scientific environment in relation to technical material involving basic and practical theoretical concepts of acquisition and analysis of geoelectrical data based on geological criteria, whose aspects are addressed in the book and of interest to professionals and researchers involved in the theme. The main target audience for this material are undergraduate students (Geology, Geophysics and Environmental Engineering) and postgraduate (Geosciences and Environment), as well as users of Applied Geophysics in general, because it provides subsidies for the choice of more suitable geophysical methodologies in studies for abstraction and preservation of groundwater, considering resolution, costs and deadlines. The lack of specific knowledge leads to an often inadequate use of geophysical methodologies, which makes the data collected and processed inaccurate and not consistent, with consequent discredit of the methods used. The content of this book addresses both theoretical questions about geoelectric methods and extremely practical issues in the development of field techniques and arrangements, providing guidance in data collection and interpretation, as well as several illustrations on the methodology. Historical cases involving objectives and varied geology are presented and discussed, providing the reader with inputs for the evaluation and choice of the most appropriate methodology.
We thank all the professionals who, in some way, collaborated to the conclusion of this work, with emphasis on the professionals of the Institute for Technological Research of São Paulo and the São Paulo State University. We particularly highlight the following collaborators for their participation in the various stages of the work: PhD Professor Walter Malagutti Filho, geologist researchers Régis Gonçalves Blanco and Carlos Alberto Birelli, PhD Professor César Augusto Moreira, for the technical content; Fernanda Bacaro and Richard Fonseca Francisco, for the review; architect and designer Maria Carolina de Oliveira Braga, for the graphic illustrations.