Fairbairn Dam Emerald Flooding January 2008
Different Scenario for Emerald if Fairbarin Dam was at 100% Capacity in January 2008
In January Emerald was lucky that the inundation wasn’t much greater, which could have occurred if the dam wasn’t so depleted of water.
Prior to January 2008 Fairbarin Dam was at 35 per cent full due to the drought; with a deficit of 800,000ML before the catchments were inundated with heavy rainfall in January. Outflow peaked at 3pm on Tuesday, January 22, with 3000 cubic metres per second of water over the spillway.
At the Emerald flood recovery group's community meeting on Saturday, May 24, the Bureau of Meteorology's Peter Baddiley gave a SunWater presentation on the flood.
One of the scenarios addressed were:
- What if the dam was at 100 per cent before the rain fell, dumping in excess of 300mm in parts of the catchment area?
It would have started spilling immediately, reaching 4.4 metres over the spillway on Sunday, January 20.
- The spillway height would have been 5.4m on the Tuesday, realising a flood peak of possibly 16m or 16.5m with a flow rate of 4300 cubic metres a second.
- If this rain event happened prior to 1972 there would have been two flood peaks, the first with a 5500 cubic metre a second flow rate on the Saturday morning, followed by a second peak on Monday of the same volume.
- The Fairbairn Dam is designed to handle a flow rate of 15,6000cm/s, more than five times the January event.
- The flood was deemed a 1 in 200-year event.
- It would take a 1 in 43,000 year event to test the dam's design.
- "There was no concern for dam safety," Mr Baddilley surmised.
| Ensham Open Cut Coal Mine near Emerald Queensland|| Ensham Open Cut Coal Mine near Emerald Queensland|
These are photographs of Ensham Open Cut Coal Mine near Emerald, Queensland.
The Fairbairn Dam on the Nogoa River overflowed in January, 2008 putting a major flood through Emerald.
The mine flood system was designed for a 1-in-100 year flood of the river, but someone made an error!
The river overflowed the mine flood protection system, then flowed into the open cut shown in the photos. The open cut is greater than 60m deep and you can see the enormous velocity of the water. A dragline has a boom about 100m long, and a good portion of it is underwater.