Muddy Waters: The Weather Service’s water quality service arrives at the Great Barrier Reef

Megan Thompson

September 13, 2023
3 minutes read

the main points

  • We are testing AquaWatch, a “weather service” for water quality, on river flows to the Southern Great Barrier Reef.
  • This pilot site will monitor sediments and dissolved organic carbon fluxes between the Fitzroy River and the ocean.
  • The data will initially be made available to traditional owners and scientific partners, with longer-term plans to make it widely available to the community.

Near the southern region of the Great Barrier Reef (GBR), the Fitzroy River enters the ocean. The river is famous for distributing sediment in the form of huge brown columns heading towards the sea, affecting the natural environment and tourism in the area.

Aside from changing the blue coastal waters of Keppel Bay to a dark brown color that reduces visibility, the sediments are causing problems at depth. It prevents essential sunlight from reaching marine plant life such as seaweed.

This limits the growth of seaweeds, which need sunlight for photosynthesis,” said Dr Nagor Chirokoro, our senior research scientist.

“In addition, light feeds phytoplankton as it passes through the water column. So the sediment reduces that as well, making the area less biologically productive,” Nagor said.

A sediment column at Darumbal Sea Country Keppel Bay where water from the Fitzroy River mixes with seawater.

The Southern Great Barrier Reef is home to a colorful array of fish and other marine life, which attracts tourists from all over the world. This marine life plays a vital role in the vibrant coral reef ecosystem and requires sea grasses and phytoplankton.

It is not only sediments that are washed into the sea. The river captures dissolved organic carbon and washes it away, affecting carbon exchange between land and oceans.

Satellite image from Sentinel Hub showing sediment flow from the Fitzroy River into Keppel Bay and the southern Great Barrier Reef.
© European Union, contains modified 2023 Copernicus Sentinel data, processed using EO Browser.

“Imagine phytoplankton photosynthesising in the ocean just like plants do on land,” Nagor said.

“This helps remove carbon dioxide from the atmosphere. When dissolved organic carbon blocks the light that phytoplankton need for photosynthesis, it reduces this process.”

Meanwhile, other measurable parameters such as chlorophyll levels in the water can be an indicator of a potential algae bloom.

“Harmful algal blooms can be devastating to marine ecosystems when they produce toxins that can cause health problems and even kill fish,” he said.

View from sea and sky

Due to this interchange between land and sea, where the Fitzroy River meets the sea at Keppel Bay in the Darumbal Sea region, it is a prime location to test AquaWatch Australia’s new mission. This mission aims to develop a “weather service” for water quality.

We have installed two advanced HydraSpectra sensors so far, one on the river and one in the bay. We will test the AquaWatch system to monitor sediment and dissolved organic carbon fluxes from land to sea. The two sensors on the water will feed the data to a central data center, where it can be combined with satellite data from space.

A HydraSpectra water sensor is mounted on a buoy at Darumbal Sea Country in Keppel Bay, where we monitor sediments and dissolved carbon plumes.

Dr. Alex Held is the AquaWatch mission commander. He said Earth observation involves using satellites to view, monitor and measure what is happening on land and in the waters of our planet.

“It’s the technology that allows you to navigate using GPS, get a weather update, or learn about wildfires near you,” Alex said.

“Using hyperspectral imaging to measure colors in water, Earth observation satellites can give us information about water quality over a large area. But sensors on the water are important for validating what we see from space and ensuring the data is accurate, as well as providing more regular updates.” From what we get from satellite data.

“These two data sets can be combined into data models and processed using artificial intelligence (AI) to give us near real-time monitoring and even forecasts of water quality up to a few days ahead.”

CSIRO scientist Gemma Kerske reviews data streams from a water quality sensor.

Transform data into impact

While our scientists are testing the system at the GBR pilot site, we are also exploring how to get water quality data to the people who need it to guide their water management decisions.

For example, understanding how much sediment is present, and exactly where it is coming from along a river, can help guide actions to mitigate agricultural runoff or manage riverbank integrity. AquaWatch can also be used to measure the success of any land and water management decisions in terms of water quality outcomes.

The hope is that AquaWatch will provide the kind of reporting and forecasts that can be used to improve water quality, starting with pilot sites like GBR and expanding across the country in the coming years.

As part of this process, an AquaWatch Community of Practice is being created for water managers, scientists, traditional owners and partners to learn more about AquaWatch and how to engage with us in the development phase.

We are also looking for partners who want to co-invest and help us build the system. Our partners benefit from early access to data and have the opportunity to co-design to achieve their goals.

(Tags for translation)Great Barrier Reef water quality

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