Can we monitor European habitats from space?
As part of the Biodiversa+ Habitat Pilot project, our researchers set out to investigate whether we can efficiently monitor inundation of grasslands and marshes using satellite imagery.
Using ESA Sentinel-2 satellites, which fly over Europe every five days, we can map patterns over time and space. The frequency at which this is done is much higher than when relying on field monitoring.
This system enables INBO to accurately map the frequency of inundation and the problems of habitat desiccation (where, when and how often). This makes it clear whether a grassland is frequently inundated, or whether valuable marshes are, on the contrary, slowly drying out.
Inundation detection generally works very well in open habitats such as grasslands and marshes. This was validated at 86,981 locations through on-site mapping, evaluation of previous aerial photographs (from the same date) and drone imagery.
Challenges
It is not yet clear whether hydrological dynamics can be fully mapped using ESA Sentinel-2 satellites, as atmospheric conditions – such as variable cloud cover across years and regions – influence these dynamics. To assess this impact, longer-term monitoring of the habitats on the ground is necessary.
It also remains a challenge for computer models to detect water beneath dense vegetation such as reed beds. Furthermore, clear agreements are needed between EU Member States on how this data is analysed and modelled. Only in this way can we ensure that monitoring is carried out in a harmonised manner across the board.
Image above: example of predicted inundated areas (INBO)