Academic tech expertise helping save the platypus
May 2024
Monitoring impacts of urban development on waterways is essential for Melbourne Water to protect and improve waterway health to protect stream-dependent species such as platypus.
May 2024
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Research conducted at Melbourne University with the support of Melbourne Water has demonstrated that the suitability of a waterway as habitat for platypus and fish is impacted by the area of impervious surfaces (such as roofs and roads) connected to the waterway through traditional drainage.
Native species such as fish and platypus are likely to decline in waterways in urban growth areas unless solutions can be found that limit the volume of stormwater reaching the stream.
For priority greenfield developments in the city’s outer suburbs, the Healthy Waterways Strategy (2018–2028) set water-harvesting and infiltration targets with the aim of maintaining the natural hydrology of the waterway, reducing the degradation of waterways due to development.
Nearmap is playing a pivotal role in helping to monitor how much urban development is occurring in each priority area over time.
Habitat Suitability Models (HSMs) for native fish, platypus and macroinvertebrates, developed by Melbourne University Waterways and Ecosystems Research Group, have been developed to help in the planning and management of waterways. Habitat Suitability Models (HSMs) predict the probability of particular waterway species occurring at locations through the landscape.
The map image below shows the network of natural waterways within the Melbourne Water catchment.
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Directly Connected Imperviousness (DCI; the proportion of impervious surface in a catchment drained with traditional underground piped networks), is an important input to the models that predicts how urbanisation will impact the natural hydrology of waterways and therefore the overall condition of habitat.
“Even small changes in DCI can have an impact and if the change reaches two percent of a catchment or above, it’s ecologically critical.”
Trish GrantPrincipal, Waterways, Melbourne Water“It doesn’t take much for a catchment to be over two percent,” said Trish Grant, Principal, Waterways at Melbourne Water. “It’s not just about a lack of green space – it’s about how we design buildings and roads. For example, traditionally paved roads capture water and direct it into the drainage system, but if you can build a car park or roads with water-sensitive urban design, or to harvest stormwater when it rains, then impacts to the waterway can be decreased.”
The picture below shows an example of water-sensitive urban design – a raingarden designed to collect excess water and reduce runoff into the surrounding landscape.
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In 2020, Trish Grant logged-on to the Nearmap NAVIG8 customer event and attended a session showing the capabilities of Nearmap AI. During that session, Trish realised that Nearmap AI data layers had potential to automate the identification of impervious and pervious surfaces on new and historic surveys and saw an opportunity to improve the efficiency, accuracy and speed of analysis of Melbourne Water’s impervious surface mapping.
“We were having trouble with new impervious area maps taking years to acquire and effectively being outdated by the time it was received.” said Trish “So I reached out to my Melbourne Water colleague Al Danger and Associate Professor Chris Walsh from the Waterway Ecosystem Research Group to suggest testing Nearmap AI for our purposes”.
“Sampling our waterways over the last 30–40 years has built knowledge of where species are and are not likely to occur.”
Al DangerSenior Asset Manager for Waterways, Melbourne Water“Habitat Suitability Models (HSMs) allow us to add sophistication by combining species distribution knowledge with environmental data such as landuse, stormwater runoff and other environmental factors, to effectively predict where species will occur as the landscape changes,” said Al Danger, Senior Asset Manager for Waterways at Melbourne Water.
“Further, we can manipulate parameters inside those models to predict what’s likely to happen in the future under various scenarios, like modified waterway hydrology (increased DCI) or climate change, decrease or increase in streamside vegetation or habitat connection via fish barrier removal – super-powerful predictions– that can help us illustrate these scenarios to our customers and partners,” said Al Danger.
Melbourne Water links its Habitat Suitability Modelling to a prioritisation tool called Zonation, to determine where best to invest to revegetate waterways and to reduce imperviousness over the next 10 years. The HSMs coupled with Zonation identify habitat benefits for platypus, more than 40 taxonomic groups of macroinvertebrates, and 16 species of native fish.
Accessing regularly updated data sets for urban footprint and vegetation available through Nearmap AI will help support the ongoing use of the models for strategy evaluation and development.
The map image below shows the Habitat Suitability Model (HSM) output for macroinvertebrates used during the Healthy Waterways Strategy development process. Dark green = very high habitat suitability, green = high, yellow = moderate, brown = low, red = very low.
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“We can specifically tailor management actions to best combat impact and set expectations for what is likely to happen for strategy and reporting purposes” said Al Danger.
Another critical predictor in the HSMs is the proportion of vegetation near the stream. Melbourne Water also uses Nearmap AI to monitor streamside vegetation over time to see if it is changing as a result of revegetation efforts and to identify areas where clearing in the streamside area has occurred.
AI data can help Melbourne Water understand the impacts of streamside revegetation.
The comparison image below shows a section of Jacksons Creek in Sunbury – slide to see how Nearmap AI highlights areas of medium-high vegetation (green), water body (blue), and low vegetation (yellow). You can see an area along the right hand side of the stream with minimal vegetation.
Melbourne Water is tracking and reporting against the HWS targets for stormwater and revegetation and is evaluating the strategy to see how well it is achieving its aims. Nearmap AI will be critical for the end of strategy evaluation in 2026 to help determine how effective the strategy has been at protecting and improving waterways, particularly with respect to preventing waterways from declining in urban growth areas. It will also be used to track how impervious surface areas are increasing outside of priority areas through activities such as infill development.
With access to Nearmap imagery, the Melbourne Water team is also considering how location intelligence can be used to help maintain awareness of issues in the landscape they may not have monitored before, like the density and size of farm dams, and associated changes through time.
The comparison image below shows two captures in Sunbury, Victoria. Slide right to see how the area looked in March 2024, compared to the image taken in January 2018. The highlighted AI layers indicate asphalt (yellow), buildings (red), water body (blue), and medium-high vegetation (green).
Development monitoring
Sunbury, Victoria
While HSMs were originally developed to predict habitat in rivers and streams, new HSMs are currently being developed for wetlands to predict frog and wetland bird habitat suitability. Nearmap AI for wetland vegetation and impervious areas is likely to be used as an input to these new models as well as to future updates to the original stream HSMs.
Al Danger is optimistic about the future. “It’s the quality but it’s also the speed at which we can achieve monitoring results,” he said.
“It was formerly taking years to get quite an average product; now with the Nearmap data we’ve got it down to a couple of months for a quality product – it’s been transformative for us.”
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