Study Area The study area is located within the Sydney suburb of East Hills. The study area is a small urban catchment centred on the East Hills Railway station, which drains through a stormwater pipe network to the Georges River. Much of the study area is also affected by flooding from the Georges River, where a series of blockwall “finger levees” have been constructed to reduce flood velocities and the hazard experienced to the occupants of riverfront dwellings. The catchment is wholly within the Bankstown local government area. Report Structure This report is divided into two parts. The first part provides background on the study and further discussion of the available data, modelling approach and results from the flood model that was established to analyse flooding within the catchment. The second part is a technical report that provides additional detail concerning the flood model, model results and flood mapping, which is included as an appendix. Outcomes from the Study Outcomes from this study include: (i) a database of all drainage assets within the study area; (ii) establishment of a computer model capable of assessing flood behaviour; (iii) information on flood behaviour under existing catchment conditions; and (iv) a model that can be used to assess flood mitigation options and future development proposals. Database of Drainage Assets All data collected for the study has been included within a GIS database. This allows the data to be spatially represented across the study area and allows for easy retrieval of the data as required. Information in the database includes data for some 88 stormwater pits and 83 stormwater drainage pipelines. Other catchment data, including aerial photography, property cadastre, building footprints and the terrain surface (based on ALS survey) is also represented in the database. Computer Modelling A numerical computer model was developed for the catchment to simulate flood behaviour, using the computer program known as TUFLOW. Surface flows are represented in the model through a 2-dimensional grid covering the entire study area. The stormwater pipe network is included as 1-dimensional elements within this grid. Full details of the modelling approach, modelling parameters and other assumptions are included in the Flood Model Report, which is included in Appendix A. Existing Flood Behaviour Design flood behaviour has been computed for a range of floods, ranging from relatively frequent events to more extreme floods, under existing (2007) catchment conditions. The model produces a grid of results over the study area providing data on flood levels, flood depths and flood velocities. Flood level contours have also been prepared showing contours of equal flood heights throughout the study area. This data is provided digitally and can be overlaid on base mapping such as aerial photos and cadastral plans showing property boundaries. All flood model results have been provided to Council for incorporation into their GIS computer system. Much of this information is also included as A4 sized plans included in Appendix A. It is intended to develop a database of properties that are at risk of being affected by flooding as part of the floodplain management study, which is the next phase of the investigations. This will define the problem areas within the catchment and allow an assessment of potential flood mitigation options.

Study Area The study area is located in south west Sydney and includes the central part of the suburb of Picnic Point. The northern part of the catchment is predominantly urban; the southern part includes parts of the Georges River National Park, in particular the Yeramba Lagoon. The catchment drains gradually south, through a stormwater pipe network towards the Georges River. The Sydney South Electricity Substation is also located within the Picnic Point catchment. The Picnic Point catchment is wholly within the southern section of Bankstown City Council Local Government Area (LGA). Outcomes from the Study The main outcomes from this study include:,

Study Area The study area is located in south west Sydney and includes parts of the suburbs of Revesby Heights, Revesby, Panania and Picnic Point. It is an urban catchment that drains in a south-easterly direction through a stormwater pipe network to the Georges River. The Morris Gully catchment is wholly within the southern section of Bankstown City Council (LGA). Outcomes from the Study The main outcomes from this study include:,

Study Area The study area is located in south west Sydney and covers the northern part of the suburb of Chester Hill. It is an urban catchment that drains through a stormwater pipe network in a north-easterly direction to the Parramatta Council Local Government Area (LGA). The Wolumba catchment is one of the sub catchments of Duck River, and is wholly within the north western section of Bankstown City Council (LGA). Outcomes from the Study The main outcomes from this study include:,

Study Area The study area is located in south west Sydney and includes parts of the suburbs of Punchbowl, Mount Lewis and Greenacre. It is an urban catchment that drains through a stormwater pipe network and the Sydney Water open concrete channel drainage system in a north-easterly direction towards the Cooks River in the neighbouring Local Government Area (LGA) of Strathfield. It is important to note that the Punchbowl catchment does not represent the entire (hydrological) catchment to Juno Parade (at the Bankstown LGA boundary). The entire stormwater catchment is located in two LGAs; the western part of the catchment is situated in Bankstown City Council and the eastern part is situated in Canterbury City Council, covering parts of the suburbs of Roselands, Wiley Park and Lakemba. This report focuses on the study area only, although the model was developed for the entire catchment. For the remainder of this document and for clarity, the Punchbowl catchment in this report refers to the study area and is wholly located within Bankstown LGA while the entire catchment will be referred as the Punchbowl/Roselands catchment. Outcomes from the Study The main outcomes from this study include:,

Study Area The study area is located in south west Sydney at the northern end of the suburbs of Revesby and Padstow. It is an urban catchment that drains in an easterly direction through a stormwater pipe and open channel network to Salt Pan Creek, a tributary of the Georges River. The catchment includes the South Western Motorway (M5) east from approximately Queen Street to Salt Pan Creek. The River Road, Gibson Avenue and Fairford Road cross the catchment (and the motorway via overpasses) in approximately a north-south direction. The Fairford Road catchment is wholly within the Bankstown City local government area (LGA). Outcomes from the Study The main outcomes from this study include:,

Study Area The study area is located in south west Sydney and covers most of the suburbs of Chullora and Potts Hill and small parts of the suburbs of Yagoona, Greenacre and Bankstown. It is an urban catchment that drains through a stormwater pipe network and Freshwater Creek in a north-easterly direction to the Cooks River. The catchment is bounded by the Hume Highway to the south and east, and the railway line to the north. The Rookwood Road catchment is wholly within the Bankstown City local government area (LGA). Outcomes from the Study The main outcomes from this study include:,

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.

Study Area The study area is known as the Greenacre Park catchment. It is one of four catchment areas that drain to the Upper Cooks River, which flows to Botany Bay through the Cooks River. The study area is located mostly within the Sydney suburb of Greenacre, in the north-east corner of the Bankstown Local Government Area. The catchment commences near Greenacre Road and flows in a northerly direction to the Hume Highway. From the Hume Highway, the catchment drains through the State Rail Authority’s Chullora Workshops to join the Upper Cooks River. Report Structure This report is divided into two parts. The first part provides background on the study and further discussion of the available data, modelling approach and results from the flood model that was established to analyse flooding within the catchment. The second part is a technical report that provides additional detail concerning the flood model, model results and flood mapping, which is included as an appendix. Outcomes from the Study Outcomes from this study include: (i) a database of all drainage assets within the study area; (ii) establishment of a computer model capable of assessing flood behaviour; (iii) information on flood behaviour under existing catchment conditions; and (iv) a model that can be used to assess flood mitigation options and future development proposals. Database of Drainage Assets All data collected for the study has been included within a GIS database. This allows the data to be spatially represented across the study area and allows for easy retrieval of the data as required. Information in the database includes data for over 1,000 stormwater pits and 900 stormwater drainage pipelines. Photos of culverts and other sketches are also linked to the database. Other catchment data, including aerial photography, property cadastre, building footprints and the terrain surface (based on ALS survey) is also represented in the database. Computer Modelling A numerical computer model was developed for the catchment to simulate flood behaviour, using the computer program known as TUFLOW. Surface flows are represented in the model through a 2-dimensional grid covering the entire study area. All pipes, drains and creeks are included as 1-dimensional elements within this grid. Full details of the modelling approach, modelling parameters and other assumptions are included in the Flood Model Report, which is included in Appendix A. Existing Flood Behaviour Design flood behaviour has been computed for a range of floods, ranging from relatively frequent events to more extreme floods, under existing (2007) catchment conditions. The model produces a grid of results over the study area providing data on flood levels, flood depths and flood velocities. Flood level contours have also been prepared showing contours of equal flood heights throughout the study area. This data is provided digitally and can be overlaid on base mapping such as aerial photos and cadastral plans showing property boundaries. All flood model results have been provided to Council for incorporation into their GIS computer system. Much of this information is also included as A4 sized plans included in Appendix A. It is intended to develop a database of properties that are at risk of being affected by flooding as part of the floodplain management study, which is the next phase of the investigations. This will define the problem areas within the catchment and allow an assessment of potential flood mitigation options.

This report presents the Flood Study undertaken to define flooding characteristics of the Lansdowne catchment in the Bankstown City Council area in NSW.