The photo accompanying your article on dredging rivers last week clearly shows some of the problems causing flooding north of the Brunswick River.
The historic man-made design in Marshalls Creek and the ocean end of the Brunswick River show a jigsaw of rock walls that have drastically changed the way water and sediment move over time. This has impacted Brunswick Heads, Billinudgel, Ocean Shores, New Brighton and South Golden Beach, and will continue to do so.
I don’t know the historical origin of the rock works, but I guess it was to create a ‘safer’ place for human dwellings and for boating. Your photo shows two aspects that are glaringly problematic. The bar is known to boaties as one of the worst to navigate on the east coast of NSW, being very narrow and silt-laden. I have seen several boats smashed to pieces there.
And further, why was the rock wall or weir across the mouth of Marshalls Creek built decades ago? Maybe for oyster farming? It prevents floodwaters upstream along the north coastline from exiting to the ocean quickly. I remember a conversation with some North Head locals. We needed a ‘rock party’ i.e. a bunch of us to remove that rock dam one moonlit night! Never happened, sorry to say. But in the photo you can see a swelling lake behind the dam and the narrow outlet for all of Marshalls Creek on the upstream end of the island. Not ideal when there’s a torrent coming downstream.
Check BV Flood History online for some background. And maybe Cr Duncan Dey could put his hydrological expertise to the task.
