MARVIS: Nitrates Virtual Sensing for Safer Aquifer Recharge
Nitrate control is central to water safety, whether for general water supply systems or for managed aquifer recharge with alternative sources. While traditional laboratory testing provides reliable reference values, sampling and analysis often occur at fixed intervals, precluding continuous monitoring of conditions and associated risks.
MARVIS is a digital tool that addresses this gap with an affordable and efficient approach based on artificial intelligence (AI). Instead of relying on expensive and specialised nitrate online probes, MARVIS functions as a virtual sensor: an algorithm that estimates variables that are difficult or costly to measure by using other signals that are easier to obtain. Particularly in the case of MARVIS, the inexpensive field parameters such as pH, temperature or conductivity, are combined to generate near real-time nitrate estimates. These inputs are straightforward to collect and markedly less expensive than a dedicated nitrate probe.
The development of MARVIS required gathering data from demonstration sites considered within the MARCLAIMED project. Afterwards, an AI model learns the statistical relationships between the predictor variables and nitrate levels, the response variable. Once trained, the model can ingest live sensor signals and perform a continuous estimation, providing operators with rapid awareness of water quality in alternative water resources used for recharge. For new sites, MARVIS can apply transfer learning, a technique where a model trained elsewhere is adapted to local conditions using a modest amount of site data. By reusing prior knowledge and fine-tuning only what is necessary, reliable performance can be reached with fewer samples and shorter setup time.
By turning low-cost, widely available measurements into an actionable nitrate estimate, MARVIS supports timely and informed operational decisions. This capability ultimately helps reduce monitoring expenses, enhance aquifer protection, and promote the safe and efficient use of alternative water resources for recharge.
