The $72 million rebuild of Brisbane's inner city Riverwalk has met with significant delay as a result of environmental engineering complications.

The original Riverwalk, which was considered one of the Brisbane’s most iconic infrastructure works, was severely damaged in 2011 when heavy flooding scoured the city.

The bustling river connection consisted of a floating structure running for 850 metres along the Howard Smith Wharves, connecting the inner city suburb of New Farm to the Brisbane CBD.

Rebuilding work only commenced in May of 2013, with the launch of a $72 million project to restore and upgrade the full extent of the Riverwalk and radically upgrade its resilience.

While the government confirmed in February that the fully revitalised structure would ready for operation by the middle of this year, Lord Mayor Graham Quirk has announced that this date will now be postponed to September as a result of environmental engineering complications which are hampering the project.

“It’s later than initially indicated,” said Quirk. “When you’re dealing with the river, river engineering is an inexact science.”

Tides and the abundance of rocks on the river bed are two of the chief problems afflicting reconstruction work, leading to a delay of at least three months in the completion date.

The walkway is nonetheless mostly complete, with 26 out of a total 30 deck pieces already installed.

The new structure will differ markedly from its predecessor, consisting of a far more durable fixed structure moored to the riverbed as opposed to the floating, water-borne original.

Engineers claim this will lead to greatly enhanced durability, with the new structure capable of withstanding a one-in-2000 year flood event as a result of 37 concrete piles embedded firmly in the riverbed. This compares favourably with the preceding floating structure, which was only capable of withstanding a one-in-a-century flooding disaster.

Other features of the new and improved Brisbane Riverwalk will include an increase in net width of around a metre, separate pedestrian and cyclist areas measuring 2.5 metres and 3.5 metres in width respectively, and a rotating opening span which will allow for the passage of smaller vessels.

The rebuilt structure will also possess a new alignment which will extend further over the water for the majority of its distance, enabling both pedestrians and cyclists to better enjoy Brisbane’s riverside scenery and environment.