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Extended Experimental Investigation | Bulimba Creek

Observations













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Site one: Hemmant Nature Creek Reserve
















The two sides of the creek varied greatly in vegetation type and pattern. On the far bank from the testing site, virtually untouched mangrove forest was present for the entire thirty metre verge zone. However, on the bank adjacent to the Hemmant Nature Creek Reserve, mangroves had been extensively cleared, to be replaced with native sclerophylls. Large expanses of turf had been laid, and major housing developments were not further than fifty metres from the creek edge. The presence of a railroad bridge accounted for erosion adjacent to it; a small stream outflow was found that stretched back about one hundred metres to a main road overpass. During rain or storms, run-off carrying oils and silt will flow into the creek. The creek appears to be affected by the tide from the Brisbane River. Severe erosion on one side of the creek could be seen where mangroves had been cleared, thus causing an approximate metre drop to the water. Erosion was less severe or non-existent on the opposite bank, where the mangrove held the mud together and created a gentle slope to the water. The mangrove esturary appears to have alluvial soil. I suspect that, because of nearby wetlands and the flat areas around the Creek Reserve, the area is a flood plain.

Site Two: Winstanley Street Bridge, Carindale

The verge on both sides of the creek has been severely altered. The far side was extensively cleared and had been succeeded by a population of weedy grasses and ground covers. Terracing and pathways had been constructed on the near side where testing was conducted. An open drain could be seen about twenty metres from the Winstanley Street bridge. Oils were spilling out and general rubbish such as organic matter, plastic wrapping and bottles were present. In the shallow waters of the drain, algal blooms flourished, but the drain outflow was not toxic to kill aquatic life. On the contrary, tadpoles and small fish were thriving in the small cloth divide created to filter rubbish from the drain going into the creek. Extensive clearing had been carried out, with parklands created on the near side. There were sparse plantings of trees, some sort of native conifer and eucalypts. There was little creek cover, with evidence of erosion further upstream. A main road bridge passed over the creek. Drainage patterns have been altered with clearing; water no longer naturally flows to the tributaries. The result is that the small tributaries are dry and have turned into gullies. A new housing development had sprung up when we visited, which was probably responsible for the drain, with Carindale Shopping Centre less than five hundred metres away. Further upstream was a golf course.

Site three: Wishart Community Park

Opposite bank was cleared for pasture, with horses grazing. Bank was sloped so manure would most likely flow into the creek as run-off increasing organic matter in the creek as well as introducing coliform bacteria such as Escherichia Coli. What looked like a willow was growing by the creek. The tallest trees were eucalypts and most of the verge vegetation had been kept intact on the nearside bank. However, a small section had been cleared to create the reserve and housing development abutted the creek. There was little evidence of erosion, except for where the paths ran along the banks of the creek; here, a small brick wall had been erected which dropped down to a mud flat. Elsewhere along the bank, small untouched coves existed that were shaded by the tall trees. Creek cover is considerably greater upstream where the creek narrows and runs through river stones. Again, drainage patterns would have been altered with the clearing of trees for the reserve and leveling of the site. This means the flow of run-off may not reach trees which had relied on a stream of run-off for hundreds of years.
















Website created by Corey Washbourne 2006 for Term 2 EEI assessment