Day 4

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Paper title Actionable information on Cyanobacteria in inland waters from a combination of EO data and optical in-situ sensors
Authors
  1. Steef Peters Water Insight BV Speaker
  2. Marnix Laanen Water Insight BV
  3. Semhar Ghbrehiwot Water Insight BV
  4. Lazaros Spaias Water Insight BV
  5. Annelies Hommersom Water Insight BV
Form of presentation Poster
Topics
  • A7. Hydrology and Water Cycle
    • A7.06 EO for monitoring water quality and ecological status in inland waters
Abstract text Cyanobacteria are a persistent problem in inland waters. They hamper the use of water for recreation and drinking purposes. Being odorous and foul-looking they are also an unwanted guest in urban waters. Water Insight has supported a number of water managers in the Netherlands and abroad to monitor the onset of cyanobacteria blooms and take early and appropriate action.
Based on simultaneous measurements of cyano-chlorophyll (with lab fluoroprobe) and optical Phycocyanin (WISPstation) we were able to establish a good relationship between the two parameters. This relationship could be extended to biovolume based on a large Dutch database of measurements. Water managers often prefer biovolume as indicator for the abundance of cyanobacteria. The general validity of the conversions should be investigated further.

We present 3 use cases explaining the usability of our concept to monitor the blooms with the most suitable combination satellite observations and our proprietary optical sensors.

Case 1: Bathing water monitoring
A WISPstation was used in the two small lakes (“Agnietenplas” and “Bosplas”) in the Netherlands to demonstrate the added value of continuous in-situ monitoring of the growth and decline of cyanobacteria. The optical data record clearly shows the added value of high frequency measurements opposite to a 2-weekly sampling frequency. Short-term peaks are recognised and the bathing water can be opened or closed on a daily basis instead of a 2 weekly basis.

Case 2: Determination of the representativeness of WFD monitoring stations
Lake Lauwersmeer suffers from high-concentration blooms. The purpose of the Water Framework Directive is to take measures to improve the water quality to a ‘good’ ecological status, however, sparse sampling and therefore less insight makes it difficult to take effective measures. In a pilot of H2020 e-Shape, satellite data was used to map the EO-base phytoplankton biomass for WFD reporting in Lake Lauwersmeer, and study the representativeness of the existing monitoring stations.

Case 3: Early warming for nuisance of blooms in a recreational harbour.
In this case in-situ optical measurements of the WISPstation serve two purposes: the high-frequent measurements are used as early warning of upcoming blooms, while the spectral data serve as calibration of atmospheric correction in this turbid and cyanobacteria infested lake Volkerak. Using this technique significantly improved the quality of Sentinel-2 BOA reflectances. Based on the early warning for blooms, the water manager temporary closes a small harbour preventing the nuisance blooms to enter.

EOMORES has received funding from the European Union’s Horizon 2020 research and innovation programme grant agreement 730066
e-Shape has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement 820852