One question that keeps popping up in Brisbane is, “Why is the Brisbane River so brown?”
Most people will automatically equate the brown colour to the idea that the river water is dirty or polluted. The colour of the river doesn’t mean it’s polluted or dirty – in fact, it’s cleaner than it’ll ever be. However, seeing it blue does looks more pleasing to the eye, as most people will agree.
A University of Queensland student is determined to turn the water into blue. Jesper Nielsen, who has been planting bacopa in Jindalee, believes that this can change the river’s colour.
Mr Nielsen is close to completing his PhD looking for a solution to the river’s brown colour. His findings show sand in the middle of the river whilst mud is all on the mud banks. According to him, it’s this mud that turns the water into brown as it gets re-suspended continuously by the tide.
Last year, Mr Nielsen built a 10m vertical “turbulence tower” that would help get the job done. The tower consists of a mast supported on a legged base that sits on the river bed. It has a capacity to support various testing mechanisms. He won the research award at the Healthy Waterways Awards gala event last year for this. The tower will help him understand the flow of the river in order to solve its murky suspended sediment issue.
With his findings, he devised a “cure,” which he said lies with the river’s mudbank and a freshwater plant called Bacopa monnieri. This fresh water plant showed up along the river following the 2011 floods and despite the saltier conditions, it flourished on the river’s muddy shores. Having seen this, Mr Nielsen and his team started replanting the plant to keep the mud on the banks. His timeline? He’s confident that if he gets more people to help, he can complete this project in four years or even less.
Paul Maxwell of Healthy Land and Water said, however, that while Mr Nielsen’s efforts are truly admirable, given the sediment coming down from the upper catchment and from stormwater in urban areas, the problem is more complex. He said that replanting of the plants is a good thing but a wider approach is needed.
In the meantime, the Brisbane River flows on, in all its murky, brown glory.
