Identification of algae/cyanobacteria bloom in inland water bodies

Drinking water is an essential substance for human being and securing its stable quantity and quality requires both appropriate landscape management and monitoring systems. Freshwater water reservoirs/lakes and slowly running rivers are sensitive to rapid phytoplankton development (cyanobacteria and algae) especially during period of hot summer. Massive outbreaks cause oxygen depletion when the phytoplankton biomass decays. Additionally, cyanobacteria may produce toxic compounds (cyanotoxins) that can have negative impacts on human health and frequent regular monitoring of water quality is needed. Here, small satellites with appropriate VNIR/SWIR bands, short revisit time, and high spatial resolution and close to real-time data processing can help in a detection of bloom development and estimation of its concentration and spatial distribution in a water body.

The study brings preliminary results from a year monitoring of the drinking water reservoir (16 km², Svihov, Czech Rep.) with the focus on horizontal distribution of pigments concentrations of chlorophyll a (Ch_a) and phycocyanin (Pc). The satellite Venμs and Sentinel-2 data (2018) has been employed together with in-situ fluorescence quantification of dominant phytoplankton species and pigments along the reservoir (6 sampling places, 2 week period). We got promising results of estimating the Ch_a concentration from satellite data. Moreover, the 620 nm band of the Venμs can be used to detect the presence of cyanobacteria blooms based on the Pc absorption. Except of the fresh water reservoirs the higher spatial resolution of the Venμs allows application of the algorithms to smaller inland water bodies which are often used for recreational purposes.