Tuesday, January 11, 2011. : Despite Brisbane being supposedly flood-proof, a flood of epic proportions begins to inundate the city. The city of Brisbane is located on the Brisbane River, after which it was named. The river was discovered in June 1823 by three ticket-of-leave convicts, and named by explorer John Oxley who came across the convicts quite by accident. After surveying the river for 80 km upstream, Oxley delivered an enthusiastic report on the river, and a convict settlement was established in 1825. The Brisbane River catchment covers an area of approximately 15,000 square kilometres. It is fed by the Lockyer-Laidley Valley, which then drains into the Brisbane River in the Brisbane Valley west of Brisbane. Another major tributary is the Bremer River, which meets the Brisbane River at Moggill. In January 1974, Brisbane and nearby Ipswich were hit by a catastrophic flood. This was the result of an exceptionally wet preceding year, made worse by Cyclone Wanda, which developed into a rain depression after it crossed the coast. It was recognised that a new dam was needed to offset the likelihood of another such flood. Over the next decade, measures were taken to expand Somerset Dam, which released water into the Brisbane River, and to construct another larger dam, the Wivenhoe, which was completed in 1985. For decades, Wivenhoe protected Brisbane from any further threat of floods. 2010 saw the development of a La Nina weather pattern which brought unusually high rainfall to eastern Australia. Central Queensland was already experiencing some flooding by 10 December. On Christmas Day 2010, Cyclone Tasha crossed the coast at Cairns, bringing heavy rain along a vast section of the coast and inland. Major centres such as Rockhampton and Bundaberg were badly affected, while the river systems inland, at Chinchilla, Dalby and St George were stretched to breaking point. Heavy rainfall began falling throughout the southeast on Christmas Day and continued on and off through January 2011. On 10 January, the city of Toowoomba, at the top of the Great Dividing Range, experienced unprecedented flash flooding. This sent a 7 metre high wall of water down the range, flooding the Lockyer Valley and raising water levels in Wivenhoe Dam to 190% and higher. Fourteen people were killed in this one flash flood alone. With all the floodgates open, the Brisbane River was filled to capacity and, by early afternoon on 11 January 2011, began to break its banks. Over the next two days, the Brisbane River continued to rise, inundating around 50 suburbs, while the Bremer River in Ipswich also caused major flooding. The flood peaked at 4.46 metres at 4:01am on January 13 before beginning to slowly recede.
Posted on: Sat, 10 Jan 2015 21:00:01 +0000
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