B-PHOT for New FWO Project: Listening to Groundwater With Optical Fiber

We are happy to announce that a new FWO Senior Research Project has been approved that quite literally goes to the source: groundwater. The project asks a deceptively simple question with far-reaching implications for water management and climate resilience: can we listen to groundwater to better understand how it flows?

Groundwater flow models are essential tools for predicting drought resilience, assessing pumping impacts, and designing climate-adaptive water strategies. Yet these models still suffer from large uncertainties, mainly because they are usually calibrated using groundwater levels alone. What is often missing is direct, time-resolved information on groundwater fluxes: how fast and in which direction water actually moves underground. That missing piece is exactly where this project aims to be ground-breaking (yes, we mean that quite literally).

Within this interdisciplinary collaboration, VUB B-PHOT will take the lead on the optical fibre sensing side. The group will explore how advanced fibre-optic technologies can be used to detect extremely subtle signals caused by groundwater flow. By deploying optical fibres in the subsurface and reading them out with highly sensitive interrogation techniques, we aim to extract spatially distributed information about groundwater dynamics, without disturbing the aquifer and without the need for local electrical power.

Two complementary approaches will be explored. Distributed Acoustic Sensing (DAS) turns standard optical fibres into long, continuous vibration sensors, potentially allowing us to “hear” groundwater flow over tens to hundreds of metres. In parallel, fibre Bragg grating (FBG) sensors will be developed to provide quasi-distributed, directional flow information at selected locations. Together, these techniques promise a new window into subsurface hydrology that bridges the gap between point sensors and large-scale models — without giving away all the technical magic just yet.

The project brings together expertise from across VUB and beyond. Our colleagues at VUB HYDR – Department of Hydrology and Hydraulic Engineering, led by Marijke Huysmans, will focus on groundwater flux measurements, hydrogeological interpretation, and uncertainty-aware groundwater modelling. The company iFLUX contributes state-of-the-art local groundwater flux sensors and field expertise, providing an essential benchmark and real-world anchor for the fibre-optic measurements.

On the B-PHOT side, the project is led by Prof. Francis Berghmans (PI). The core research team further consists of Dr. Sidney Goossens and Dr. Sergei Mikhailov, together with a to-be-appointed PhD researcher who will dive deep — figuratively and literally — into fibre-optic sensing for groundwater applications.

The research will span the full trajectory from theory and laboratory experiments to field deployments in contrasting hydrogeological settings, including shallow unconsolidated aquifers and fractured rock systems. Ultimately, the goal is not only to measure groundwater flow, but to show how combining local and distributed flux measurements can significantly reduce uncertainty in groundwater flow models. If successful, this could change how groundwater systems are monitored, modelled, and managed.

We look forward to shedding new light on what happens beneath our feet, and perhaps, for the first time, truly listening to groundwater.