New FIber-Optic Temperature Sensors For Measuring Subsurface FLOWs – FIFLOW

The main ambition of FIFLOW is to provide new instrumentation to quantify groundwater fluxes in heterogeneous media, at an unprecedented spatial scale, to revisit some fundamental processes in hydrogeology associated to solute and heat transport in porous and fractured media or ground-surface water exchanges. Up to now, groundwater fluxes were rarely measured, but we recently validated a new method based on heat transfer allowing to estimate groundwater fluxes along an electrically heated Fiber-Optic cable (Simon et al., 2021). To fully explore the potential of this innovative method in shallow aquifers, the project FIFLOW is built on four complementary tasks which consists in (1) improving the effective spatial resolution of fiber-optic distributed sensing methods to sub-centimeter (2) developing a precise and low-cost probe to quantify groundwater-surface water exchanges, and (3), exploring the full potential of the newly developed tools – and associated methods – for groundwater flow and transport modelling through ambitious laboratory (WP3) and field experiments (WP4) on well-characterized sites. To ensure the success of FIFLOW, the consortium is composed of Geosciences Rennes, an internationally well-known laboratory in earth science, specialized in methods for sensing groundwater and watersheds, Cosys Department at Gustave Eiffel university, with expertise in distributed optical fiber sensors for civil engineering, and INRS Quebec, who is an associated partner participating to the project without funding. By providing innovative, high resolution, distributed and in-situ measurements, this new instrumental approach will serve to better characterize and monitor the state and dynamics of shallow aquifers and exchanges with the surface in order to improve the understanding of groundwater contamination and better design remediation approaches.