Benefits set to flow from stormwater study
  • Tuesday 14 December 2021

New research will help to improve the safety of local roads during storm events. Sunshine Coast Council and the University of Sunshine Coast have joined forces to investigate and test stormwater infrastructure improvements to boost our region’s resilience to flooding.

The Optimising Culvert Design project is part of the Regional Partnership Agreement (RPA) between Council and USC, which aims to advance community, environmental and economic interests of the Sunshine Coast.

Sunshine Coast Council Stormwater Services Manager Anton Dreyer said council was facing increased demand on its stormwater assets due to a number of factors, including climate change and increased development in existing areas.

“Culverts are essential pieces of infrastructure that allow water – whether from rivers and streams, tidal inlets, or stormwater – to pass underneath a bridge, road or railway without disrupting the flow of traffic,” Mr Dreyer said.

“In the Optimising Culvert Design project, a partnership study between USC and the Sunshine Coast Council, it was identified that an opportunity exists for new culvert designs to be more efficient and that older, existing culverts, could be retrofitted with a simple and cost-effective inlet modification to improve their performance. This will mean that they are less likely to overtop, flooding road crossings during storm events.  

“The importance of a properly functioning stormwater network was highlighted in March 2012, when over 300mm of rain fell in less than six hours along the coast. In that event, the capacity of the stormwater network was exceeded, and significant damage was caused to properties, businesses and infrastructure. More than 200 buildings were inundated.”

Dr Luke Verstraten said the project built on previous research collaborations between USC and the Sunshine Coast Council, including an extensive PhD investigation into culvert design by Dr Rick Jaeger as well as engineering honours students’ projects.

“This project aims to bring the ideas developed previously to a stage where they can be installed at locations across the Sunshine Coast,” Dr Verstraten said.    

“We have also conducted full scale laboratory testing at the Sunwater Hydraulics Laboratory on pipe and box culverts to establish the performance improvements following inlet modification.

“The results were even better than anticipated. After modifying the inlet with an optimised design, we found that the flowrate increased by as much as 40% in test conditions.

“Before this study finishes, we aim to capture data across the full range of flow conditions culverts typically face.

Things are looking promising since BoM has just called a La Nina for the rest of this summer.

“Regardless of what the weather gods deliver this summer, the success of the laboratory tests means that we can confidently install the optimised inlet modifications.

“We have just designed more models to test at the laboratory so that parameters can be determined for a wider range of optimised culvert designs.

“The laboratory tests also demonstrated that during normal stream flow conditions the modification did not increase the velocity of flow, which is important for maintaining the habitat connectivity of aquatic organisms along our streams.

“It is hoped that the optimised culvert design will also be incorporated into the manufacture of new culverts and major Queensland culvert manufacturers have already expressed an interest in this research.

Dr Rick Jaeger said installing the new culverts across the Sunshine Coast would be relatively simple and low-cost and had the potential to reduce risks to motorists during storm events.   

“Retrofitting existing stormwater infrastructure with the optimised culverts would be a significantly less expensive option than replacing them entirely,” he said.

“Optimised culvert inlets could help alleviate localised flooding issues associated with underperforming culverts and may be used to as part of a suite of measures to improve the performance of the stormwater network.

“The physical differences between existing stormwater culverts, and those being trialled in this project, are about the shape and entrance to the culvert.

“The retrofittable inlet modification that is being trialled in this project, simply attaches to the front of the culvert and potentially increases the hydraulic performance to levels beyond the best inlet configurations in current design standards.”  

The Regional Partnership Agreement between Sunshine Coast Council and the University of the Sunshine Coast was established in 2017. The RPA was established to cooperate in advancing the community, environmental and economic interests of the Sunshine Coast.

The driving force behind the partnership is excellent service to the community where the respective missions of the region’s own University and its Council coincide.