Prospect Creek FRMSP Report

# The Study Area\r\nThe study area comprises four sub-catchments within the Canterbury-Bankstown Council Local Government Area (LGA) that drain to Prospect Creek:\r\n\r\n* __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.\r\n* __Lansdowne Sub-Catchment__: Spanning 243 hectares, it includes residential areas alongside significant bushland and parklands, such as Lansdowne Park and Mirambeena Regional Park.\r\n* __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.\r\n* __Villawood Sub-Catchment__: The largest at approximately 740 hectares, this area comprises residential and industrial zones with a network of concrete-lined open channels.\r\n\r\nA map of the study area is shown in Figure 1-2.\r\n\r\n# Consultation\r\nCommunity and stakeholder consultation has been integral to this project. Key consultation activities included:\r\n\r\n* Engagement with the Floodplain Management Committee throughout the project phases;\r\n* Community feedback collected through online surveys, email submissions, and in-person sessions, with a total of 67 recorded responses during initial consultation;\r\n* Public exhibition of the draft study and plan, incorporating input from 57 engagements; and\r\n* Targeted discussions on identified issues, such as voluntary house raising and stormwater management concerns.\r\n\r\n# Modelling of Flood Behaviour\r\nCanterbury-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.\r\n\r\nThe 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.\r\n\r\n# Flood Risk Mapping & Development Controls\r\nFlood risk mapping for the Prospect Creek sub-catchments categorises the area into three flood risk precincts, guiding development controls:\r\n\r\n* __High Flood Risk Areas__: Areas prone to significant flood damages and evacuation challenges, where development is generally restricted.\r\n* __Medium Flood Risk Areas__: Zones with moderate risk, where damages can be mitigated with suitable controls.\r\n* __Low Flood Risk Areas__: Regions with minimal risk where most developments are permitted, subject to planning regulations.\r\n\r\nAdditionally, overland flow precincts have been identified to account for shallow inundation areas, enabling tailored development controls.\r\n\r\n# The Flood Problem\r\nA comprehensive flood damages database was developed to evaluate flood impacts and inform flood mitigation strategies. Key findings include:\r\n\r\n* Approximately 2,667 properties are impacted in the Probable Maximum Flood (PMF) event, with over 60% located in the Villawood sub-catchment.\r\n* 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.\r\n\r\nFlood mitigation measures were assessed, and recommendations for effective floodplain management have been outlined to address these challenges.