Online platform to monitor Chlorophyll-a in our water bodies

The Flanders Environment Agency (VMM) has a wide range of responsibilities in the domains of water, air and environment (e.g. climate adaptation). The Water Monitor Department of VMM has, among other tasks, the task of measuring, modelling and reporting surface water quality and water soil quality. In support of the European Water Framework Directive, the quality element phytoplankton is reported by VMM on the basis of Chlorophyll-a concentrations in relevant water bodies. Chlorophyll-a concentration is currently measured in 100 rivers and 16 lakes.

To support VMM with this task, our remote sensing experts in water quality monitoring use free Copernicus Sentinel-2 satellite images and remote sensing technology to produce time series of Chlorophyll-a maps. These Chlorophyll-a products are provided to VMM via the online WaterMonitor platform developed by NAZKA Mapps. The WaterMonitor allows VMM to easily search, navigate and monitor Chlorophyll-a temporally and spatially for Flemish water bodies.

The WaterMonitor retrieves its information from the Sentinel-2 satellites, which pass by every 5 days. Chlorophyll-a content is derived from the satellite images. Unless clouds obscure the satellite view, VMM can access Chlorophyll-a maps of most of our inland water bodies every 5 days within 24 hours after Sentinel-2 image acquisition.


In addition, the WaterMonitor includes for each water body of interest the OWL code (i.e. classification of the Flemish surface water bodies according category, type and statute), the thresholds for Chlorophyll-a Ecological classes (good, mediocre, inadequate and bad) and the Chlorophyll-a maps with a colour code optimized for Water Framework Directive reporting. The VMM in situ Chlorophyll-a measurements are also included for comparison.

We developed the first beta version of the static WaterMonitor together with NAZKA Mapps in the framework of the H2020 DCS4COP project. In the summer of 2020 we released a new version of the WaterMonitor to improve our services for near-real-time water monitoring including an additional product NDAVI, an aquatic vegetation index, in close collaboration with the EODaS programme (Earth Observation Data Science) of the Flanders Information Agency, NAZKA Mapps and VMM. This innovative project is hereby a contribution in taking new steps in introducing digital transformation and innovation in the Flemish Government.