With the spotlight burning bright on the water infrastructure in the eThekwini Municipality, much has been said about their distribution network, with regards to maintenance, development projects and also its use of technology in the water business.
We learnt from the recent water crisis affecting the northern parts of the metro that staff from the Department of Water and Sanitation have to physically go out and find the problems.
Problems in the network relating to flow and volume are still traced by humans, but the City uses a satellite detection method when it comes to leaks.
This satellite is in orbit above earth.
IOL recently posed questions to the City about why they still use old methods of distributing water to residents and found out more about how they use satellites to detect leaks.
This technology, however, cannot help track down other problems, like the most recent one, where the air pressure in the system was not at functional levels, causing a low pressure of water, the City confirmed.
“eThekwini Municipality currently has a EWS satellite leak detection project. The aim of the project is to use satellite technology to detect leaks in the drinking water pipeline network of eThekwini Municipality over a three-year period.
“The use of satellite-based technologies detects leaks in drinking water pipelines using a patented algorithm that has been developed and demonstrated in many parts of the world.
“The system is able to detect fresh-water leaks in urban water supply systems by analysing multispectral images and presenting its findings on a web-based Geographical Information System (GIS). By overlaying a layer of identified leaks on a map together with streets, pipes and leak size information, the resulting leak detection technology can concurrently cover thousands of square kilometres.
“To do this, it searches for the spectral ‘signature’ of fresh water (a dielectric constant),” eThekwini spokesperson Gugu Sisilana said.
The satellite is based on microwave reflectometry theory and is able to penetrate soil and water and is also sensitive to dielectric constants.
Water, being a polar molecule, is made up of dipoles and therefore has a dielectric constant, according to Physicist Thomas Jones from the University of Oxford.
This enables the discovery and measurement of water in soil.
After the satellite scans the affected area, the leak is confirmed using acoustic leak detection equipment.
“Leak sounds are related to the type of pipe, size of pipe and pressure inside the pipe. Typically, water flowing through a pipe does not make noise, unless disturbed.
“The sound generated from leaks is transmitted through the pipe wall, surrounding soil structure, as well as the water itself. Leaks sounds will typically travel farther in rocky soils and soils with a relatively low water table. Therefore, using acoustics is a reliable method to confirm a leak without excavating,” the City explained.
One important factor to consider about the satellite leak detection system, is that confirming the leak through acoustic technology will be useless if the pipe does not have the required pressure.
“In the absence of a pressurised pipeline, the use of acoustic technology will be challenging and ineffective,” it said.