Quantitative estimations of aquifer properties from resistivity in the Bolivian highlands

Etzar Gómez,Gerhard Barmen,Viktor Broman,Torleif Dahlin,Jan-Erik Rosberg

doi:10.2166/h2oj.2019.007

Etzar Gómez, Gerhard Barmen + Show 3 more

Open Access

https://doi.org/10.2166/h2oj.2019.007

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Journal: H2Open Journal	Publication Date: Jan 1, 2019
Citations: 4	License type: CC BY 4.0

Affiliation: Lund University, Higher University of San Andrés

Abstract

Abstract Resistivity data constitute the largest part of the available information to assess the hydrogeological characteristics of the aquifer system near Oruro, in the central part of the Bolivian Altiplano. Two aquifers are part of this system; top unconsolidated sediments storing fresh water in their granular voids, overlying fractured hard rock formations where saline water was detected in connection to some faults. This study proposes an indirect and cost-effective way to estimate aquifer hydraulic properties for the groundwater management in the region. Hydraulic conductivity and transmissivity in the top aquifer were estimated using an empirical linear relationship between hydraulic conductivity and resistivity. This latter parameter, as well as the aquifer thickness, were obtained from the inverted models corresponding to the geoelectrical tests performed in the study area (electrical resistivity tomography, transient electromagnetic soundings and vertical electrical soundings). The highest estimated transmissivity values are ∼4.0 × 10−2 m2/s located in the centre of the study area, the lowest values are ∼3.4 × 10−3 m2/s, located around thermal intrusions to the south and where the top of the bedrock is shallow (∼20 m depth) to the west. The methodology presented in this study makes wider use of resistivity measurements to identify promising groundwater production sites.

Highlights

Groundwater management and aquifer assessment rely on the reasonable knowledge of its hydrogeological characteristics, i.e., transmissivity (T ), hydraulic conductivity (K ), storativity (S) and specific storage (Ss) (Fetter 2001; Tizro et al 2010)
To estimate hydraulic parameters from geoelectrical tests using a linear relationship, the target aquifer should be clearly visible in terms of resistivity and thickness from the inverted models
Two vertical electrical soundings (VES) measurements are reported at the same sites of stations 1 and 2, their corresponding resistivity models are shown in Figure 3 as columns

Summary

Introduction

Groundwater management and aquifer assessment rely on the reasonable knowledge of its hydrogeological characteristics, i.e., transmissivity (T ), hydraulic conductivity (K ), storativity (S) and specific storage (Ss) (Fetter 2001; Tizro et al 2010). The conventional ways to estimate these parameters are through pumping tests, slug tests, permeameter measurements and grain size analysis (Fetter 2001). These tests can be expensive, time-consuming and depend on the existence of boreholes and sampling points conveniently distributed over a study area (Soupios et al 2007; Perdomo et al 2018). The correlation between resistivity and hydrogeological properties

Results

Discussion

Conclusion