An assessment of dilution tests and ambient temperature logging for quantifying groundwater flow in the Neogene aquifer

In this work, we assess the use of single well dilution tests and ambient temperature logging for quantifying groundwater flow within the Neogene aquifer, across the Nete catchment, in Belgium. This assessment is performed by gathering existing data, performing additional field tests, and analyzing all information using analytical or numerical models. A literature review was performed first in order to identify the required materials and methods. In the end, three dilution tests were performed on a shallow test well, and one test on a deep well to demonstrate the feasibility of the approach for the entire Neogene aquifer. A collection of 73 temperature logs was gathered, of which 27 were performed within the Nete catchment, and five were performed during this study. The interpretations of these data clearly show the usefulness of both approaches to advance the characterization of the hydrogeological system in terms of the quantification of groundwater fluxes. Moreover, comparison of the obtained results with the groundwater flow models illustrates that different tracer studies are heavily needed. As this work concerns a preliminary assessment of the two approaches, we also make several recommendations to further refine the proposed methodologies.