High rainfall to continue over Spring
The recent outlook has included a potential for a weak La Niña weather event, bringing heavy rains to south-eastern parts of Australia and a higher risk of floods in the northeast catchment.
Following steady rain over July and August, water storages across Victoria and NSW are filling rapidly with the Hume Dam already sitting at 95 per cent capacity this week after good rainfall over the weekend.
Murray Darling Basis Association (MDBA) began increasing releases again from Hume Dam on Friday, September 3.
MDBA acting Chief Executive Andrew Reynolds said the MDBA increased releases to 10 GL per day on Friday to manage airspace within Hume Dam in response to forecast rainfall. Releases increased to 22 GL per day on Saturday as significant stream flow responses were observed.
“By releasing water, the MDBA reduced the flood peak from close to 70 GL per day to 22 GL downstream of Hume Dam,” Mr Reynolds said.
“Releases from Hume Dam are likely to stay close to 22 GL per day for several days, subject to inflows generated in the upper catchments. We expect the levels at Hume Dam to continue to increase over the next few days.
“These releases mean that flows at Albury and downstream will remain slightly above the river channel in some locations due to high flows also in the Kiewa River – which joins the Murray River downstream of Hume Dam.”
Mr Reynolds said there is a high degree of confidence the Hume Dam will fill this year.
Modest pre-releases of 4000 megalitres per day from the Hume Dam occurred in early August to maintain airspace, however, were stopped after a few weeks there was less rainfall than predicted.
“Close to 19 gigalitres were from Hume Dam from 7–15 August to maintain airspace in the dam.
“These initial pre-releases will stay within river channel and not cause downstream flooding, as they are relatively small volumes.
“We will work with downstream communities before we move to any more significant pre-releases.
“We will endeavour to keep them within the channel capacity where any flooding impacts would be very minor.”
Last month, the Bureau of Meteorology’s general manager of water and agriculture,
Matthew Coulton advised that conditions in the north-east catchments were “very wet”.
“The catchment is wetter than it has been in several years and what this means is that it won’t take very much rain to produce a rapid response in river levels and inflows upstream,” he said.
“Our climate outlook indicates the rainfall over the coming three months is likely to be above average. In these situations, the Bureau works closely with water agencies and dam operators and provide them with continuous updates on the coming conditions in the short term and longer-term basis.
“If there is a risk of flooding the Bureau and other agencies will provide advice to local communities.”
Mr Coulton said the conditions were similar to 2016 where extended heavy rain led to flooding.
“That doesn’t mean we are going to have as wet a year, but it means that it’s plausible and it’s likely to be wetter than average and we need to keep an eye on it.”
NSW SES chief superintendent and southern zone commander Nicole Priest said the organisation will be working closely to monitor conditions particularly along the Murray River and border regions.
Regular flood bulletins will also be prepared on current and expected conditions.
“We also do high river warnings, which is
District landholders along the Murray will be on alert for the remainder of Spring as the Bureau of Meteorology forecasts above average rainfall over September to November across the region.
an equipment and livestock warning, and that will help landowners start to think about raising pumps and moving equipment and looking at how they are going to manage their land during those river rises,” she said.
“We have been working very closely with Victorian SES to collaborate on our messaging so that it is similar messaging. The communities on each side of the river have very different impacts so it is really important that both warnings are provided during the river rise and for those individual communities as they go downstream.”
If the BOM’s prediction of a wetter than average spring holds true, farmers could expect another good season so long as they can get on their crops come harvest.