Eastern Creek is a tributary of South Creek which in turn is a tributary of the Hawkesbury River. The Eastern Creek catchment is situated in New South Wales (NSW) approximately 35 km west of Sydney and 15 km east of Penrith. Much of the Catchment is composed of unzoned or rural land but changes to zoning in a number of regions are likely to significantly change land usage and hence the Catchment’s response to flooding. In particular the North West Growth Centre (NWGC) and Western Sydney Employment Area (WSEA) are two regions that are currently being planned and released for development. Urban consolidation in existing developed areas is also planned to deliver growth targets. Areas throughout the Eastern Creek catchment can become inundated from a number of mechanisms. To the north of the Catchment in the vicinity of Riverstone (at the downstream end of the catchment), the backing up of Hawkesbury River flood waters has resulted in significant flooding within the Eastern Creek catchment on a number of occasions. Additionally, intense localised rainfall may cause Eastern Creek and its tributaries to flood and inundate properties in many regions of the Catchment. This is particularly of interest in the elevated regions of the Catchment where flooding caused by backwatering of the Hawkesbury River is a non issue.

Project Objectives

The primary objective of this study is to assess the impact that changes in land use associated with proposed development will have on the catchments response to flooding and the implications for design flood flows. This will be done through comparison of design flows for the current catchment conditions and various development scenarios. Furthermore, climate change impacts will be assessed and sensitivity analysis performed on On-site Stormwater Detention (OSD) provisions. Table 1 in the report shows a summary of the model runs required as per the Brief. Further explanation of model runs for various catchment conditions are presented in Sections 1.3.1 - 1.3.7.

• Existing Catchment Conditions
• Inclusion of the Western Sydney Employment Area
• Ultimate Development under Current Local Environmental Plan
• Sensitivity Analysis of On-site Stormwater Detention Variations
• Inclusion of the North West Growth Centre
• Inclusion of all Predicted Future Catchment Changes
• Climate Change