Space: the final frontier of water treatment
Today, there are plenty of methods to track and improve water quality. Yet, the technique that stands out the most comes from space. You guessed it - remote sensing (or satellite imagery).
Remote sensing refers to the process of collecting and analyzing information about objects, areas, or phenomena from a distance, typically via satellites. Similarly, satellite imagery has to do with obtaining pictures of the Earth from satellites orbiting our planet.
In addition to other environmental applications, remote sensing can be used to monitor and predict certain water quality parameters over time. Examples of such parameters include turbidity, temperature, and chlorophyll-a. Accordingly, satellite data can be applied to examine our drinking water, public health, and fisheries. Specifically, managers of hydrologic resources can employ satellite imagery to monitor the growth and spread of algae in inaccessible areas. Recently, this kind of data has “proven fundamental to providing a global view of phytoplankton and their role in, and response to, climate change.” (ESA).
Phytoplankton (or suspended algae) “are the prime source of organic matter supporting food webs in freshwater ecosystems,” and they rely on nutrients like nitrogen (N) and phosphorus (P) to grow. However, an excess in nutrient supply accelerates the eutrophication process. This leads to rapid accumulations of phytoplankton, which severely affect water bodies used for drinking and recreational purposes. These events are called blooms.
Blooms deteriorate water quality, they cause unpleasant odors taste, and they lower oxygen levels in waters. Additionally, they negatively affect other aquatic organisms, animals, and humans. In freshwater bodies, the most wide-spread bloom formers are blue-green algae, i.e., cyanobacteria.
In order to ensure a high quality of (drinking) water, it is essential to control the spread of cyanobacteria. (source)
The value of remote sensing
The European Space Agency (ESA) recently released satellite pictures featuring algal blooms suffocating the Coast of Japan (source). The images were captured in June 2019, approximately 130 km off Hokkaido Island (Japan’s second largest island). The pictures show dense concentrations of algae stretching over 500 km across and 200 km wide.
This example highlights the value of remote sensing for coastal water monitoring. Large, inaccessible or even dangerous areas of the Earth suddenly become accessible. This data can be used for future comparisons of the same geographical area.
However, what makes remote sensing even more useful for hydraulic resource managers is that it can be applied to monitor surface waters such as lakes/reservoirs, ponds, streams, etc. to improve water quality more successfully.
Integrated space-earth monitoring
Solely collecting water samples to measure water quality does not suffice. Instead, a combination of different methods has been proven to be most effective. This is where we can exploit satellite imagery by incorporating it in already-existing water quality monitoring techniques. Water characteristics differ from meter to meter. Each section of a body of water contains different distributions of algae, for instance.
The MPC-Buoys are systems that collect real-time, in-situ water quality data. By adding remote sensing, i.e., collecting pictures from satellites, we receive a bird’s-eye view of a large or inaccessible body of water. We then take this data and calibrate the algorithms of the buoys to treat water more accurately by using ultrasound technology.
In short, satellite remote sensing in combination with in-situ water quality data provides higher spatial and temporal coverage.
By combining real-time water quality monitoring, a web-based software and ultrasound technology, the MPC-Buoys offer the ultimate treatment against algae blooms.