The Rosetown area has been subject to significant recent inundation due to storm surges, combined with high tides, that have flooded the area, via the Maria Creek drain. Once the area becomes inundated, there is no local drainage infrastructure resulting in pooled water sitting in the area for extended periods.
Council is undertaking an investigation that will primarily focus on reducing the risk of future inundation of the area due to storm surge while also looking at what options can be provided to give the area some type of drainage system. It may be assessed that provided the storm surge issue is rectified that a local drainage system is not considered a priority. However, as additional development occurs in the area, more stormwater runoff will be produced that may require the area to be provided with a more formal drainage system.
Given the low-lying nature of the area, it may be that the area can only be reliably drained via a pumped system, if high tide levels within Maria Creek would prevent a gravity system from operating effectively. This issue is likely to be exacerbated by future sea level rise.
The scope of this study will include review of several strategies already proposed by community members and will include consideration of high-level concept options to prevent storm surge from tidal events, including:
- Review LIDAR survey data of the area and identify breach points where tidal water is inundating Rosetown area.
- Review predicted peak tidal levels from information available;
- Potential site/s for retention basin/s;
- Levee walls – if these can be made without compromising other resident areas, through transfer of water to other areas;
- Stormwater drainage system investments such as culverts and kerb/channel construction; and
- Any other strategies that can mitigate and overcome future storm surge and potential flooding events.
- The suggestion of a weir as having a positive impact on Maria Creek flooding is as yet unproven but is also under investigation.
Completing this strategic piece of work is the crucial first step in regard to having baseline data set that will assist Council in applying for multiple streams of grant funding, as outcomes to mitigate against future events are expected to be very costly. These outcomes and other improvement strategies will be part of a broader discussion with residents from Rosetown (such as a community forum) prior to any physical works commencing.
A key action upon completion of the study with be the formation of a Rosetown working group which will work alongside Council ensuring decisions are consistent, considered and actions are implemented in a timely manner. There will be more information on this to come a later date.
