South west rivers respond to better winter
Released 15 Nov 2016
Better winter rainfall in 2016 has lifted the flows of many of the State’s key south west river systems, a recently released annual assessment by the Department of Water reveals.
“Generally, it’s been an improvement from last year thanks to better rainfall from May to October, assisted by cooler temperatures in the majority of the south west land division,” Executive Director Science and Planning Greg Claydon said.
Mr Claydon said 2016 appeared to be a lot wetter to many people and it had been better than a number of recent previous years, however, this year’s rainfall was still below the long term average in most places, and it had fallen over a longer period compared to last year.
“This year we have seen a number of strong cold fronts and cloud bands bringing rainfall to our lower South West and South Coast regions,” Mr Claydon said
“The 2016 streamflow shows how highly seasonal and variable our streamflow can be, and how it is directly influenced by the intensity and duration of rainfall events in each area.
“In summary, the streamflow sites we report at showed much better results for 2016 than last year, with 73 per cent of the streamflow sites average or above, compared to only 22 per cent last year.”
The Blackwood River was the highest of the sites reported, recording well above average flows for the year, with almost six times, or 384 million litres, more water measured moving through the system than in 2015.
“The South Coast’s rivers from the Young in the east to the Frankland in the west have all had above average streamflow for the year, compared to just the Young River achieving that in 2015,” he said.
“The Frankland River had four times more water move through it this year than last, and the Young River over six times more water than in 2015.
“Although they are still under average, the Murray and Hotham flows have improved from extremely low flows last year, both recording around three times more water through the system this year.
“While streamflow for Gingin Brook is below average it is still an improvement on 2015 flows, with around 35 per cent more water flow this year than last.”
Mr Claydon said rainfall and streamflow is a good indicator of the recharge to water resources each winter, and private and public dams had mostly recorded better inflows than last year.
“The more flow we get, particularly after dry years, the better for the river health and any capture and recharge to dams and aquifers in the catchment.”
Mr Claydon said department scientists had worked out that a 10 per cent reduction in rainfall can equate to up to a 30 per cent reduction in streamflow.
“This assessment is just one of many methods to keep our fingers on the pulse of the bigger picture of how our water resources are tracking to each year’s weather.”
Streamflow Jan to Oct (ML megalitre = a million litres)
The Department of Water’s Climate and streamflow summary can be found here:
Additional water data and information is available on the Department of Water’s Water Information Reporting portal at water.wa.gov.au
Contact: Peter Collins
Phone: (08) 6364 6848 / 0434603441