Stormwater Victoria held their annual conference in early June in Marysville, Victoria. Three presentations on the program were delivered by Engeny on three very different topics.
Scott Dunn: Unlocking Colac’s Future Development Potential via Engagement
The need for the Colac Stormwater Development Strategy has been driven by Council’s planning department as a key input to the Colac 2050 planning strategy to guide the future development of Colac.
The objective of the Strategy was to assess the performance of existing drainage infrastructure through detailed flood modelling and to define the extent of overland flow paths that could impact future rezoning of the town. The Strategy identifies sustainable and economic solutions to address areas of poor drainage performance and enable the future development of Colac to be appropriately planned for. The drainage works identified in the Strategy have been proven, through detailed modelling, to facilitate future development on large areas of currently flood affected land.
The presentation detailed the engagement process undertaken as part of this project with comparisons drawn to engagement undertaken as part of similar projects.
Glenn presented results from multiple flood models across Melbourne where the full ensemble of temporal patterns has been run through hydraulic models. Answering key questions:
- What is the variation in results between the different temporal patterns within an individual duration within an event?
- Is the variation associated with temporal patterns consistent throughout the catchment or does it vary?
- Can we predict what the critical temporal pattern will be just by looking at the hyetograph?
- What impact do storages (retarding basins and informal ponding) have on results?
- Where should our modelling effort be directed to get the best result with limited time and money?
Engeny’s investigation of the Moonee Ponds Creek catchment assessed the benefit of using existing reserves and other open spaces within urban environments for large scale flood storage that can help to minimise downstream flood risk.
In our assessment, completed with the City of Melbourne, Engeny has investigated:
- Where are opportunities for flood storage located throughout an urban catchment?
- Are they in locations that can interact with the existing local drainage networks?
- How much storage volume should be provided at each potential location to facilitate reductions in peak flows?
- How many storages should be present throughout a catchment and do more storages always equate to additional reductions in peak flows along receiving waterways?
- Can providing flood storage actually make downstream flooding issues worse?
- Should the locations of storages be distributed throughout the catchment or grouped at the downstream end of a catchment to provide the most benefit?
This presentation explored the complexities of providing a solution for peak flow reductions within an urbanised creek system, with consideration of the whole of catchment outcomes.