10 years of temperature monitoring experiments using electrical resistivity tomography: What have we learned?

The electrical resistivity of the subsurface is dependent on the temperature. This makes electrical resistivity tomography a good candidate for monitoring temperature variations within the context of aquifer thermal energy storage or thermal tracer test. In this contribution, we review the advances made in the development of ERT for monitoring heat storage and heat tracing experiments during the last ten years. We highlight the common limitations related to ERT such as the need for a petrophysical relationship for a proper survey design, as well as the concerns related to noise and inversion. We also point towards the solutions available to overcome those limitations and guidelines for successful monitoring experiments. We think this contribution will help practitioners and scientists to make the appropriate choice when designing or exploiting shallow geothermal systems.