Casuarina Street Emergency Works | Hydraulic Assessment

Flooding within the Barron River associated with Tropical Cyclone Jasper in December 2023 resulted in flood waters breaking through a section of Casaurina Street in Holloways Beach, north of Cairns, which created a new creek mouth. Severance of Casuarina Street resulted in isolation of over 40 residential properties. While a temporary access road was established, WMS Engineering was engaged to determine if it was hydraulically beneficial for the new creek mouth to remain open through the construction of a bridge, as opposed to re-establishment of the road embankment.

The options assessed included a bridge, a culvert crossing and a lower level causeway at the breakthrogh location. The assessment required the development of a local Barron River hydraulic model, assessment of an existing case scenario, evaluation of the three options, and provision of recommendations on future considerations for upgrades in the area. The modelling was completed within an extremely tight timeframe.

The outcomes of the hydraulic assessment showed that the construction of a bridge would offer significant local hydraulic benefits in the form of flood level reductions within the upstream Holloways Beach residential area. The flood level reductions did however come with significant velocity increases through the creek mouth that will need to be managed as part of the bridge design.