Prospect Creek FRMSP Report

Brief description

# The Study Area
The study area comprises four sub-catchments within the Canterbury-Bankstown Council Local Government Area (LGA) that drain to Prospect Creek:

* __Georges Hall Sub-Catchment__: Covering approximately 145 hectares, this area predominantly features residential land with notable reserves, such as Crest Reserve and Garrison Point Reserve.
* __Lansdowne Sub-Catchment__: Spanning 243 hectares, it includes residential areas alongside significant bushland and parklands, such as Lansdowne Park and Mirambeena Regional Park.
* __Miller Road Sub-Catchment__: Covering 50 hectares, this area includes residential zones with no defined water channels, relying on overland flow paths and a piped drainage network.
* __Villawood Sub-Catchment__: The largest at approximately 740 hectares, this area comprises residential and industrial zones with a network of concrete-lined open channels.

A map of the study area is shown in Figure 1-2.

# Consultation
Community and stakeholder consultation has been integral to this project. Key consultation activities included:

* Engagement with the Floodplain Management Committee throughout the project phases;
* Community feedback collected through online surveys, email submissions, and in-person sessions, with a total of 67 recorded responses during initial consultation;
* Public exhibition of the draft study and plan, incorporating input from 57 engagements; and
* Targeted discussions on identified issues, such as voluntary house raising and stormwater management concerns.

# Modelling of Flood Behaviour
Canterbury-Bankstown Council has implemented a consistent and advanced approach for modelling stormwater catchment flooding. The methodology integrates a dynamically linked 2D/1D hydrodynamic model (TUFLOW), which simulates flood behaviours with precision.

The TUFLOW model uses a two-dimensional grid to represent surface terrain while incorporating one-dimensional elements for stormwater pipes and channels. Overflow from drainage elements is accounted for, allowing flows to spill onto the grid and replicate overland and sheet flows across floodplains.

# Flood Risk Mapping & Development Controls
Flood risk mapping for the Prospect Creek sub-catchments categorises the area into three flood risk precincts, guiding development controls:

* __High Flood Risk Areas__: Areas prone to significant flood damages and evacuation challenges, where development is generally restricted.
* __Medium Flood Risk Areas__: Zones with moderate risk, where damages can be mitigated with suitable controls.
* __Low Flood Risk Areas__: Regions with minimal risk where most developments are permitted, subject to planning regulations.

Additionally, overland flow precincts have been identified to account for shallow inundation areas, enabling tailored development controls.

# The Flood Problem
A comprehensive flood damages database was developed to evaluate flood impacts and inform flood mitigation strategies. Key findings include:

* Approximately 2,667 properties are impacted in the Probable Maximum Flood (PMF) event, with over 60% located in the Villawood sub-catchment.
* Average Annual Damages (AAD) across the sub-catchments exceed $93.7 million, with the Villawood sub-catchment contributing a significant portion due to its low-lying industrial areas.

Flood mitigation measures were assessed, and recommendations for effective floodplain management have been outlined to address these challenges.