Document Type

Honors Thesis

Publication Date

Spring 5-6-2026

Abstract

Groundwater flow in shallow heterogeneous environments is often difficult to characterize using a single geophysical method. This study applies an integrated approach combining azimuthal resistivity anisotropy, self-potential (SP) measurements, DEM-derived terrain indices, and three-dimensional electrical resistivity tomography (3-D ERT) to delineate preferential groundwater pathways at the Old Works Golf Course in Anaconda, Montana. Azimuthal anisotropy analysis from eighteen 2-D ERT profiles revealed a dominant directional dependence in electrical conductivity, indicating a structural or sedimentological control on subsurface flow. The anisotropy results indicate a preferred conductivity direction of approximately 200°–210° in azimuth (0° is north), suggesting that groundwater movement is guided toward the south–southwest. Self-potential data showed negative anomalies aligned with the anisotropic direction, reflecting localized downward hydraulic gradients and active water movement. DEM-derived topographic wetness index (TWI) and terrain ruggedness index (TRI) highlighted surface areas prone to moisture accumulation and infiltration. The 3-D ERT inversion revealed a continuous low-resistivity zone between approximately −3 m and −8 m depth, extending across the central portion of the survey area. This conductive feature represents a possible shallow groundwater flow corridor consistent with the SP anomalies, high TWI values, and anisotropy-derived flow direction. The integrated geophysical and topographic analysis establishes a coherent conceptual groundwater flow model, demonstrating that combining multi-method datasets provides a more consistent interpretation of shallow subsurface hydrology than any single method alone.

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