After almost three months travel time, the flood peak in the Darling River has arrived at the Menindee Lakes.Inflows of nearly 60,000 megalitres per day were experienced during the third week of April, but are now falling and have now reduced below 40,000 megalitres per day. Airspace in the lakes minimised the flood impact around Menindee township and downstream. Upstream at Wilcannia, the river is falling steadily and no further rises are anticipated from this event.
High flows generated from major floods in northern NSW and southern Queensland catchments during January
have merged and around 4,400 gigalitres has passed through Bourke so far in this event. The peak reached Tilpa
this week with the Darling River rising to a peak of 12.9 meters and a flow of 130,000 megalitres per day. Peak
flows are expected to reach Wilcannia in about 10 to 12 days time and arrive at Menindee in mid-April. The NSW
Office of Water and State Water Corporation are continuing to manage operations at Menindee Lakes in
anticipation of the forecast inflows.
Management of Menindee Lakes
Issue 4 – 24 February 2012
Major flood flows were generated from northern NSW and southern Queensland catchments during January and are making their way into the Darling River. The NSW Office of Water and State Water Corporation are continuing to manage flood operations at Menindee Lakes in anticipation of the impending substantial inflows. Two significant flood peaks are approaching Bourke; from the east (Barwon River) and from the north Culgoa/Bokhara River systems). They are forecast to merge during the first week of March, with the Barwon River flows expected to arrive slightly earlier than those from the Queensland Rivers. The scale of this event at Bourke and downstream is expected to be at least the peak level of 13.
Heavy rainfall and flooding in northern NSW and Queensland has triggered pre-releases from the Menindee Lakes system for the third time in two years. With the Menindee lakes storage levels already increasing as a result of high flows earlier this summer, there is limited capacity to manage the impending additional flow.
As a result, the NSW Office of Water and State Water Corporation began flood pre-release operations on Thursday 2 February 2012, increasing releases from 15,000 megalitres per day to a target of 29,000 megalitres per day by Tuesday 14 February. However, as the scale of flooding in the upstream valleys is becoming apparent, the rate of releases from
Menindee Lakes will now continue to rise further to target 35,000 megalitres per day by Friday 17 February. These releases to the Lower Darling will make room in the storage for the second period of high inflows that are expected to arrive in March and April 2012, and will protect the township of Menindee from extensive flooding. Currently the various flood peaks are still making their way along the Gwydir, Namoi, Moonie, Warrego and Balonne/Culgoa/Bokhara river systems. Flood flows from the Moonie, Namoi and Gwydir Rivers will flow into the Barwon-Darling system first, followed by flood flows from the other Queensland Rivers. The full extent of these flood flows into the Barwon-Darling system is not yet fully clear, but it is expected to be
significantly larger than last summer, with flood peaks even higher than those experienced in 1998. This could result in the largest flood in the Barwon-Darling system since 1976.