Interpreting Variations in Groundwater Flows from Repeated Distributed Thermal Perturbation Tests.

Area of Science:

• Hydrogeology
• Geophysics

Background:

• Understanding groundwater resources in southern Nye County, Nevada, is challenging due to complex alluvial aquifer systems.
• Characterizing hydraulic properties and flow paths of regional groundwater systems is difficult.

Purpose of the Study:

• To investigate groundwater resources in southern Nye County, Nevada.
• To characterize hydraulic properties and flow paths using distributed thermal perturbation sensing (DTPS).

Main Methods:

• A multipart distributed thermal perturbation sensing (DTPS) test was conducted on a three-well complex (one pumping, two observation).
• Fiber-optic cables and line heaters were used to inject heat into the water column for 1-2 days.
• Temperature patterns in the cased well sections were analyzed to infer aquifer thermal properties and estimate fluxes.

Main Results:

• Actively flowing zones within the aquifer changed between stressed and unstressed test conditions.
• Anisotropy in aquifer permeability was evident from variations in inferred fluxes.
• DTPS-derived fluxes were consistent with the fastest solute transport observed in prior tracer tests.

Conclusions:

• Distributed thermal perturbation sensing is a viable method for assessing dynamic groundwater flow and aquifer properties.
• While DTPS fluxes correlate with rapid solute transport, they may overestimate the overall mean groundwater flux.
• The study highlights the utility of DTPS in complex hydrogeological settings.