From 16 to 19 June the team ran four consecutive survey days on the Goczałkowice reservoir on the upper Vistula in southern Poland, in collaboration with the University of Warsaw and the University of Silesia in Katowice. The reservoir is one of the main drinking-water sources for the Upper Silesian conurbation, which is the reason its water quality is watched as closely as it is.
The full instrument suite operated over the four days, the LIFL-11 alongside two mFL-12 lidars and the mHR-2 radiometer. The LIFL-11 did two separate things as the boat moved across the reservoir: it profiled the water column below it, and it measured surface fluorescence on two excitation wavelengths, 355 and 532 nm, reading chlorophyll-a on both and coloured dissolved organic matter on the 355 nm laser. Across the four days it logged more than 130,000 surface measurements over the water, resolving the relative chlorophyll and CDOM fields across the whole reservoir.
The point of taking the survey to Goczałkowice was comparison. Conventional samples were taken through the four days, and two autonomous buoys were towed alongside the boat, logging a range of water parameters continuously, so the lidar maps could be set against independently measured values along the same track.
On the last day the team left the reservoir for Farskie, a smaller still lake to the north, to sample its water and look for golden algae. Golden algae, the organism behind the mass fish kill along the Oder in 2022, is the kind of harmful bloom that early optical detection could help catch, and whether it is present at Farskie is still to be confirmed from the samples.
Our thanks to the University of Warsaw and the University of Silesia in Katowice, and to Iwona Stachlewska and Mariola Krodkiewska for the collaboration over the four days.