Innovative water utilities are using techniques that are out-of-this-world to detect leaks in their water networks – leveraging imagery captured from satellites orbiting the earth.
I recently stumbled across a story out of Victoria discussing the use of location-based analytics and satellite imagery to detect leaks in water pipes. This story struck a chord with me, as not only did it highlight an innovative use of spatial imagery, but it demonstrated a potentially effective way for water utilities to save millions of dollars in lost revenue.
On a personal level, living on one of the driest continents in the world, I was moved by the potential of this technology to help conserve one of our most precious resources.
Using location-based analytics and imagery technology in the way described in the Victorian example raises two big questions for water utility managers:
- What is the operational feasibility of using such technology?
- What considerations do utilities need to make before investing further in trialling the technology.
To answer these questions, there are three key concepts that we need to consider.
- Firstly, imagery comes in different forms. Synthetic Aperture Radar (SAR) images differ from more commonly known satellite imagery as they are captured by sensors operating in the microwave region of the Electromagnetic Spectrum (EMS). More well-known satellite imagery, such as Landsat, is captured in the visible and infrared regions of the EMS. Due to the nature of SAR, the imagery can be captured all year round, rain or shine, day or night. This means the technology enables around-the-clock monitoring of water networks – a huge advantage for utilities wanting to locate leaks as soon as they happen.
- Secondly, and perhaps more importantly, SAR imagery can be analysed in a unique way to monitor temporal changes in the ground surface – that is, variations in the ground surface over time. In the case of water utilities, they can use this capability to assess changes to the ground surface in the immediate vicinity of water mains, and determine if it has become wet as a result of leaking water.
It’s important to note that the size of the area of wet ground will determine how easily the imagery can detect it. If the wet patch of ground is relatively large, let’s say in the tens of square meters, it would be easier to detect. However, if the area of wet ground is small compared to the resolution of the satellite, the imagery may struggle to identify it.
Wet ground surfaces appear brighter in SAR imagery compared to dry surfaces, and by comparing different images across time they can analyse if a location which was previously dry has now become wet – indicating a possible new leak.
- That brings us to the third consideration – it is important to find a satellite capable of capturing images of the right resolution, that will allow us to identify and map the extent of the water leak. Detecting small water leaks will require satellites that can see finer details and vice versa.
While the technology is promising, we also need to understand its limitations, so we can make better and informed decisions. SAR produces very noisy images in urban areas, and therefore the technology is not ideal to monitor built-up areas – eliminating the possibility of identifying water leaks in suburban networks and individual backyards.
However, the technology would be very effective monitoring leaks in large trunk pipelines transporting water from reservoirs to urban distribution centres through open areas with little or no vegetation. With ruptures in these large diameter pipes accounting for significant water losses, detecting leaks in these pipes would be very beneficial.
Another piece of good news is that under certain circumstances, at some frequencies, the radar is even capable of penetrating the dry surface to identify leaks below the surface – a capability that is really quite amazing.
The compelling part of this technology is that while it may not immediately replace the current methods of detecting water leaks, such as manual visits or installation of leak detection devices, what it will do is provide convincing evidence for water crews to isolate areas of potential water leaks – saving a lot of money and effort to plug leaks in the process.
This is a time of innovation and disruptive technologies, and water utilities that are willing to think outside the box and investigate new technologies such as SAR imagery will be guaranteed to stay ahead of the game.
About the author
Dr Dipak Paudyal
Principal Consultant for Remote Sensing and Imagery