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Flood study

Hawkesbury-Nepean Valley Regional Flood Study

The Hawkesbury-Nepean Valley Regional Flood Study is a technical document describing the flood behaviour of the main Hawkesbury-Nepean River from Bents Basin near Wallacia downstream to Brooklyn Bridge, and associated backwater flooding, for existing conditions and under projected climate change. It does not include local catchment flooding or local overland flow inundation. The modelling of infrastructure options to mitigate downstream flooding is beyond the scope of this flood study and is addressed separately.
This Regional Flood Study describes the flood behaviour dominated by Hawkesbury-Nepean riverine flooding and its backwater effects. Local catchments are modelled to have the same duration rainfall event as that which causes the highest flood levels in the main river. Shorter duration events are likely to result in higher flood levels within tributaries such as South Creek, requiring separate investigations. Local councils should be consulted to ascertain whether information is available to understand the combined flood risk at particular locations in the valley.
Reports including a volume with 382 flood maps are provided here as PDFs. For specialists requiring spatial information in GIS format, please contact the data broker.

Additional Information

Field Value
Title Hawkesbury-Nepean Valley Regional Flood Study
Commission Date 27 February 2017
Publication Date 26 July 2019
Themes Emergency Management
Spatial Extent
Map data © OpenStreetMap contributors
Council/LGA Infrastructure NSW
Author/ Prepared by WMAwater
Publish date 8 August 2019
Update date 22 October 2020
Place Name Hawkesbury-Nepean Valley from Bents Basin to M1 Bridge near Brooklyn including backwater flooding up South and Eastern Creeks
Approval State Approved
Submitted for approval 10 August 2019
Submitted by Stephen Yeo
Approved 22 December 2020
Approved by dstazic
Data Comment

The Hawkesbury-Nepean Valley Regional Flood Study calculates flood levels, flood extents and flood depths for the 1 in 5, 1 in 10, 1 in 20, 1 in 50, 1 in 100, 1 in 200, 1 in 500, 1 in 1000, 1 in 2000, 1 in 5000 AEP events and the probable maximum flood (PMF). Provisional flood hazards are calculated for the 1 in 5, 1 in 20, 1 in 100, 1 in 500, 1 in 2000 AEP events and the probable maximum flood (PMF), while hydraulic categories are calculated for the 1 in 100 and 1 in 500 AEP events.

Identifier 6ee14f52-a1ab-4986-865a-14544fcb65a2