River Engineering

A decade later, harbour authorities accepted the need for a training wall to make the Fitzroy navigable for commercial vessels. Engineer for Harbours and Rivers William D. Nisbet, who had great waterway experience abroad, drew up plans for construction works to achieve 10 ft (3m) clearance at low water from Rockhampton to Keppel Bay. He recommended a curving wall be built along the southern bank at the Upper Flats with subsequent walls to be erected farther downstream. As well as narrowing the river, these other walls would close off numerous side channels which dispersed the tidal flow and further weakened the river's scouring capacity. Rather than incurring the high cost of solid stone, Nisbet proposed a cheaper timber-and-stone construction. He considered his design was an experiment for a tidal river in Queensland. In 1875, construction began at Upper Flats on what was called No 1 Wall and finished in1880. Most of the dredging spoil was deposited between the wall and the original bank to prevent it returning to the newly cut channel. [ More on Nisbet's plans.]