CSIRO and SA Water demonstrate cyanobacteria detection with sensor technology that is bound for space. 

Water Quality from Space. The CSIRO Space Optics Team is developing CyanoSat, a shoebox-sized hyperspectral imager designed and developed in Australia to monitor Cyanobacteria levels in Australian waterways. This project is a critical precursor for the AquaWatch Mission, which will establish an integrated ground-to-space national water quality monitoring system by 2026. 

Testing the technology in our own backyard.  Partnering with SA Water, the team is performing a series of hyperspectral drone flights over South Australia’s reservoirs and wastewater treatment lagoons. By comparison with in-situ water samples, these measurement campaigns will build the team’s capability in retrieving water quality parameters from hyperspectral imagery and demonstrate the value of this technology to key water management groups. 

Supporting cyanobacteria management. On the 3^rd and 10^th of May the team performed two measurement campaigns over Warren Reservoir, located in the Adelaide hills. These flights coincided with SA Water conducting algal management in the reservoir. Over 60GB of hyperspectral imaging data was successfully captured, much of which is still being analyzed.   

Preliminary Cyanobacteria Measurements 

As shown in the figure below (Ref 1.) cyanobacteria (solid) exhibits a very different reflectance spectrum in comparison to green algae (dashed). Typically, the 625nm, 650nm and 710nm bands can be used to easily identify water with a high concentration of cyanobacteria.

The two measured spectrum taken in the south-west corner of the reservoir before (blue) and after (orange) the introduction of the algaecide are plotted below. Cyanobacteria were clearly present in the reservoir during the first flight, since the 710nm peak is high and a peak is present at 650nm, both of which are absent in the second flight. Comparison with in-situ data taken by SA Water will allow validation of this exciting preliminary result. 

Future Work 

The second half of 2022 is poised to be busy as the team finalises the assembly and testing of the CyanoSat imager payload. It is expected that this exciting collaboration with SA Water will continue with further testing at Warren Reservoir and other measurement campaigns around South Australia. 

The CyanoSat team would like to thank David Antoine (Curtin Uni) for support in developing our detection approach and Peter Hobson, Jeffrey Newman and the rest of the team at SA Water for helping to facilitate this project.

References 

1. Ruiz-Verdú, Antonio, et al. “An evaluation of algorithms for the remote sensing of cyanobacterial biomass.” Remote Sensing of Environment 112.11 (2008): 3996-4008.