Premium
Delineating Alluvial Aquifer Heterogeneity Using Resistivity and GPR Data
Author(s) -
Bowling Jerry C.,
Rodriguez Antonio B.,
Harry Dennis L.,
Zheng Chunmiao
Publication year - 2005
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.2005.00103.x
Subject(s) - geology , aquifer , plume , fluvial , ground penetrating radar , hydraulic conductivity , electrical resistivity tomography , electrical resistivity and conductivity , silt , alluvium , borehole , geophysics , geomorphology , soil science , mineralogy , hydrology (agriculture) , geotechnical engineering , groundwater , radar , soil water , telecommunications , physics , electrical engineering , engineering , structural basin , computer science , thermodynamics
Conceptual geological models based on geophysical data can elucidate aquifer architecture and heterogeneity at meter and smaller scales, which can lead to better predictions of preferential flow pathways. The macrodispersion experiment (MADE) site, with >2000 measurements of hydraulic conductivity obtained and three tracer tests conducted, serves as an ideal natural laboratory for examining relationships between subsurface flow characteristics and geophysical attributes in fluvial aquifers. The spatial variation of hydraulic conductivity measurements indicates a large degree of site heterogeneity. To evaluate the usefulness of geophysical methods for better delineating fluvial aquifer heterogeneities and distribution of preferential flow paths, a surface grid of two‐dimensional ground penetrating radar (GPR) and direct current (DC) resistivity data were collected. A geological model was developed from these data that delineate four stratigraphic units with distinct electrical and radar properties including (from top to bottom) (1) a meandering fluvial system (MFS); (2) a braided fluvial system (BFS); (3) fine‐grained sands; and (4) a clay‐rich interval. A paleochannel, inferred by other authors to affect flow, was mapped in the MFS with both DC resistivity and GPR data. The channel is 2 to 4 m deep and, based on resistivity values, is predominantly filled with clay and silt. Comparing previously collected hydraulic conductivity measurements and tracer‐plume migration patterns to the geological model indicates that flow primarily occurs in the BFS and that the channel mapped in the MFS has no influence on plume migration patterns.