Aquifer recharge and recovery (ARR) is the process of enhancing natural groundwater resources and recovering water for later use by constructing engineered conveyances. Insufficient understanding of lithological heterogeneity at ARR sites often hinders attempts to predict where and how quickly infiltrating water will flow in the subsurface, which can adversely affect the quality and quantity of available water for future use.
We explored the use of electrical resistivity tomography (ERT) to aid in characterizing subsurface lithology at an ARR site near Aurora, Colorado. Some guiding principles exist for inferring lithology information from resistivity data when field borehole measurements and geophysical measurements are collocated. In our case of non-collocated geophysical and borehole data, we explored different methods of creating a resistivity-lithology transform.
The differences in this transform affect the posterior lithology distributions in multiple point geostatistical (MPS) simulations, and in turn, predictions of flow from models based on these distributions. To test the reliability of these models, we can compare measured breakthrough times of recharged water at the site to groundwater flow simulation results using the lithofacies models created by each method.