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Alluvial aquifer thickness and bedrock structure delineation by electromagnetic methods in the highlands of Bolivia

Gómez, Etzar LU ; Larsson, Måns; Dahlin, Torleif LU ; Barmen, Gerhard LU and Rosberg, Jan Erik LU (2019) In Environmental Earth Sciences 78(3).
Abstract

The porous aquifers in the area called Challapampa are the most important groundwater reservoirs that supply drinking water to Oruro city in the highlands of Bolivia. They consist of unconsolidated fluvial–lacustrine deposits, resting on a complex sedimentary bedrock and covered by a thin surficial clay layer. The settings of these geological units and the structures governing the flow patterns have barely been investigated, despite this reservoir having been utilized during the last 50 years. This study applied transient electromagnetic (TEM) soundings and electrical resistivity tomography (ERT) in the middle part of the alluvial fan of River Paria to investigate the thickness of the porous aquifer and detect the relief of the bedrock.... (More)

The porous aquifers in the area called Challapampa are the most important groundwater reservoirs that supply drinking water to Oruro city in the highlands of Bolivia. They consist of unconsolidated fluvial–lacustrine deposits, resting on a complex sedimentary bedrock and covered by a thin surficial clay layer. The settings of these geological units and the structures governing the flow patterns have barely been investigated, despite this reservoir having been utilized during the last 50 years. This study applied transient electromagnetic (TEM) soundings and electrical resistivity tomography (ERT) in the middle part of the alluvial fan of River Paria to investigate the thickness of the porous aquifer and detect the relief of the bedrock. Likewise, some results expressed as resistivity models indicate the possible existence of geological structures below the unconsolidated sediments. The average depth of investigation reached in this study is between 200 and 250 m below the surface, for both the applied methods. The geological structures inferred have similar directions as the major faults in the vicinity, from southeast to northwest, which in turn are assumed as part of fractured aquifers underlying the porous aquifers. The geo-electrical techniques were successfully tested in the study area and the resistivity models from TEM complement very well those obtained from ERT. Therefore, extended investigations using the same techniques would help to develop a more complete description of the hydrogeological settings of the aquifer system.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bolivia, Hydrogeology, Resistivity, Transient electromagnetic
in
Environmental Earth Sciences
volume
78
issue
3
publisher
Springer
external identifiers
  • scopus:85060750783
ISSN
1866-6280
DOI
10.1007/s12665-019-8074-x
language
English
LU publication?
yes
id
08c558ed-4871-4a88-bba1-ce3ad37a35db
date added to LUP
2019-02-11 13:17:19
date last changed
2019-02-11 13:17:19
@article{08c558ed-4871-4a88-bba1-ce3ad37a35db,
  abstract     = {<p>The porous aquifers in the area called Challapampa are the most important groundwater reservoirs that supply drinking water to Oruro city in the highlands of Bolivia. They consist of unconsolidated fluvial–lacustrine deposits, resting on a complex sedimentary bedrock and covered by a thin surficial clay layer. The settings of these geological units and the structures governing the flow patterns have barely been investigated, despite this reservoir having been utilized during the last 50 years. This study applied transient electromagnetic (TEM) soundings and electrical resistivity tomography (ERT) in the middle part of the alluvial fan of River Paria to investigate the thickness of the porous aquifer and detect the relief of the bedrock. Likewise, some results expressed as resistivity models indicate the possible existence of geological structures below the unconsolidated sediments. The average depth of investigation reached in this study is between 200 and 250 m below the surface, for both the applied methods. The geological structures inferred have similar directions as the major faults in the vicinity, from southeast to northwest, which in turn are assumed as part of fractured aquifers underlying the porous aquifers. The geo-electrical techniques were successfully tested in the study area and the resistivity models from TEM complement very well those obtained from ERT. Therefore, extended investigations using the same techniques would help to develop a more complete description of the hydrogeological settings of the aquifer system.</p>},
  articleno    = {84},
  author       = {Gómez, Etzar and Larsson, Måns and Dahlin, Torleif and Barmen, Gerhard and Rosberg, Jan Erik},
  issn         = {1866-6280},
  keyword      = {Bolivia,Hydrogeology,Resistivity,Transient electromagnetic},
  language     = {eng},
  month        = {02},
  number       = {3},
  publisher    = {Springer},
  series       = {Environmental Earth Sciences},
  title        = {Alluvial aquifer thickness and bedrock structure delineation by electromagnetic methods in the highlands of Bolivia},
  url          = {http://dx.doi.org/10.1007/s12665-019-8074-x},
  volume       = {78},
  year         = {2019},
}