A novel approach towards the reliable characterization of complex sedimentary aquifers

The reliable characterization of heterogeneous sedimentary aquifers, especially the identification of preferential flow paths and their connectivity remains a challenge in applied hydrogeology research and practice. However, aforementioned information is crucial for predicting subsurface flow and contaminant transport in complex deposits. Well established characterization methods such as outcrop analogue studies, hydraulic tomography, tracer testing, and direct push profiling suffer from uncertainty due to non-uniqueness of underlying inversions or insufficient temporal and/or spatial data resolution. Furthermore, the relation and effects of observed heterogeneity in hydraulic conductivity on transport is not always straight forward.

A promising novel approach to overcome the limitations of conventional hydraulic site characterization techniques is the joint application of tracer testing and direct push logging. We present a proof-of-concept field study, where conventional salt tracer testing was combined with vertical high resolution direct push electrical conductivity profiling. The method successfully captured tracer distribution in heterogeneous sedimentary deposits in-situ and visualized measured tracer distribution over time. Additional measurements, such as breakthrough-curves and surface geophysics can be easily integrated to set up ex-post simulations to further increase site-specific understanding of groundwater flow and transport processes.