Regular frontal systems, combined with north-west cloud bands that streamed across from the Indian Ocean, delivered above-average rainfall throughout most of the Murray-Darling Basin in spring.
Across the basin, the Bureau of Meteorology (BoM) reported area-averaged rain totalling 187.4 mm, 64 per cent above the long-term seasonal mean, according to Murray Darling Basin Authority (MDBA) river management executive director David Dreverman.
“Following on from high winter inflows, spring inflows to the River Murray system totalled around 8,500 GL, which is only exceeded in about eight per cent of years,” Mr Dreverman said.
“The heavy rainfall and resulting runoff, particularly in September and October, built upon already high river and storage levels produced by above-average winter rains.”
Flood operations at Hume Reservoir lasted from early September to late November.
Significant flow contributions also came from the Kiewa and Ovens Rivers, with Wangaratta on the Ovens peaking near 100,000 ML/day, the highest since September 2010.
“As a result of this flow combining with high Murray flows, the peak release from Yarrawonga Weir reached 180,000 ML/day in early October, the highest since October 1993.
“The peak from this event reached the South Australian border only last week.”
November saw the return to near-average rainfall for much of the southern Murray–Darling Basin.
Overall, the Bureau of Meteorology reported that area averaged rain for November was 22.3 mm, 44% below the long-term monthly mean.
“For the Murray catchments, this was the first month without above average rain since May this year,” Mr Dreverman said.
Temperatures across the Murray-Darling Basin were near-average in November. With catchments wet from 6 months of above-average rainfall prior to November, November’s near average rainfall still resulted in well-above average inflows.
Inflows to the River Murray System during November totalled just under 1,500 GL, well-above the month’s long-term average of around 790 GL.
Patchy light rain fell across much of the Murray-Darling Basin this week, with moderate falls mainly confined to areas of the Great Dividing Range