Twenty gauges will be installed to better monitor water flow in response to flooding in Menindi, according to the New South Wales government.
the main points:
- Construction of five gauges has already begun, according to the New South Wales Minister for Water
- The gauges will provide timely water flow information
- Each scale will cost between $40,000 and $60,000 to install and about $15,000 a year to operate.
Several homes were flooded and dozens remained in danger after authorities failed to predict the large flows that spilled into the Menindi Lakes from December to January.
According to authorities, this was at least in part due to the re-entry of unmeasured water from Taylawalka Creek into the system.
NSW Water Minister Kevin Anderson confirmed that the installation of the first of five Commonwealth-funded hydrometric stations was underway at Wilkanya, Bourke, Woolgate, Kambon and Borwarina.
“These metrics provide live information about the upstream flows from the rivers,” he said.
“This information is shared with other agencies, including the State Emergency Service and the Met Office.”
Taylawalka is a flood plain near Wilcannia, which runs alongside the Darling River.
It flows about once every decade after heavy rains in the catchment area north.
According to a Water NSW spokesperson, there are several types of meter.
“The basic flow meter is the employee measurement function [pictured above] or a series of them above the river bank used to read the water level in a recursive manner.”
“To get more information in a timely manner, more sophisticated instruments are installed in a shelter up the bank, ideally above flood levels, and sensors to read the water level or water quality are placed down the bank to sit in the water when the current is flowing.
These automated measurements are then sent via telemetry to a central database where they are captured and made available for use.
A well-maintained water meter can last a “very long time” and there are sites along Darling that have been in operation for more than 100 years, said a Water NSW spokesperson.
“These sites are the most valuable because they allow for historical comparisons,” he said.
The spokesperson said the cost of installation and maintenance varies between units, due to their requirements and location.
“A typical scale would cost in the range of $40,000 to $60,000 to install,” he said.
Its operation also depends on the complexity of the site, including what data is collected, how often it needs to be serviced, labor cost, and cost of spare parts.
“For a river flow site, it would cost an average of about $15,000 a year to run it.
“Some sites cost less and others can cost much more due to factors such as how often they have to be visited, and how far afterward.”
Locations are limited
Water NSW said there were 12 sites in the Darling system south of Bourke, before the Darling River, that reached the Menindee Lakes network.
This included scales at Wilcania and Tagliaoca.
“[They are] at the same point to calculate the total flow of the Darling River system at that point.”
“Locations for effective measurement of flows between Menende and Wilcania will be limited by the river landscape in this region.”
NSW Water Minister Kevin Anderson said the Department of Planning and the Environment is looking into feedback on the location of the remaining 15 gauges.