Electrical resistivity tomography and induced polarization for mapping the subsurface of alluvial fans: A case study in Punata (Bolivia)

TY - JOUR

T1 - Electrical resistivity tomography and induced polarization for mapping the subsurface of alluvial fans

T2 - A case study in Punata (Bolivia)

AU - Gonzales, Andrés

AU - Dahlin, Torleif

AU - Barmen, Gerhard

AU - Rosberg, Jan Erik

PY - 2016/12/1

Y1 - 2016/12/1

N2 - Conceptual models of aquifer systems can be refined and complemented with geophysical data, and they can assist in understanding hydrogeological properties such as groundwater storage capacity. This research attempts to use geoelectrical methods, Electrical Resistivity Tomography and Induced Polarization parameters, for mapping the subsurface in alluvial fans and to demonstrate its applicability; the Punata alluvial fan was used as a case study. The resistivity measurements proved to be a good tool for mapping the subsurface in the fan, especially when used in combination with Induced Polarization parameters (i.e., Normalized Chargeability). The Punata alluvial fan characterization indicated that the top part of the subsurface is composed of boulders in a matrix of finer particles and that the grain size decreases with depth; the electrical resistivity of these deposits ranged from 200 to 1000 Ωm, while the values of normalized chargeability were lower than 0.05 mS/m. The bottom of the aquifer system consisted of a layer with high clay content, and the resistivity ranged from 10 to 100 Ωm, while the normalized chargeability is higher than 0.07 mS/m. With the integration of these results and lithological information, a refined conceptual model is proposed; this model gives a more detailed description of the local aquifer system. It can be concluded that geoelectrical methods are useful for mapping aquifer systems in alluvial fans.

AB - Conceptual models of aquifer systems can be refined and complemented with geophysical data, and they can assist in understanding hydrogeological properties such as groundwater storage capacity. This research attempts to use geoelectrical methods, Electrical Resistivity Tomography and Induced Polarization parameters, for mapping the subsurface in alluvial fans and to demonstrate its applicability; the Punata alluvial fan was used as a case study. The resistivity measurements proved to be a good tool for mapping the subsurface in the fan, especially when used in combination with Induced Polarization parameters (i.e., Normalized Chargeability). The Punata alluvial fan characterization indicated that the top part of the subsurface is composed of boulders in a matrix of finer particles and that the grain size decreases with depth; the electrical resistivity of these deposits ranged from 200 to 1000 Ωm, while the values of normalized chargeability were lower than 0.05 mS/m. The bottom of the aquifer system consisted of a layer with high clay content, and the resistivity ranged from 10 to 100 Ωm, while the normalized chargeability is higher than 0.07 mS/m. With the integration of these results and lithological information, a refined conceptual model is proposed; this model gives a more detailed description of the local aquifer system. It can be concluded that geoelectrical methods are useful for mapping aquifer systems in alluvial fans.

KW - Alluvial fan

KW - Electrical resistivity tomography

KW - Induced polarization

UR - http://www.scopus.com/inward/record.url?scp=84997234890&partnerID=8YFLogxK

U2 - 10.3390/geosciences6040051

DO - 10.3390/geosciences6040051

M3 - Article

AN - SCOPUS:84997234890

VL - 6

JO - Geosciences (Switzerland)

JF - Geosciences (Switzerland)

SN - 2076-3263

IS - 4

M1 - 51

ER -