Between 7 and 12 June 2007 a low pressure system off the mid-north coast of NSW intensified and moved south. Rain had already been falling in many areas on 7 June and increased in intensity over the next 24 hours, resulting in flooding across the region. Gale warnings were issued for coastal waters and there were concerns about dangerous sea conditions.

This report presents the rainfall, water level and wave heights recorded by Manly Hydraulics Laboratory at automatic hydrometric stations for the flood event of 7-12 June 2007 in the Nepean and Hawkesbury rivers catchments. It should be noted that the data, although being put through a preliminary review to assess its quality, has not yet passed the final quality assurance process and should be viewed as raw data.

The data was collected via a network of stations which are part of a larger network of environmental data monitoring stations operated by Manly Hydraulics Laboratory. The data collected and presented in this report is detailed below:

• The principal rainfall period experienced in the mid-north coast region has been captured in four mean sea level pressure maps displayed in Figure 1.1. From these figures the low pressure system can be tracked from off the mid-north coast of NSW on 8 and 9 June until it moves out to sea on 10 and 11 June.
• Recorded rainfall amounts and intensities are summarised and plotted against intensity frequency duration (IFD) curves.
• The peak water levels recorded in the catchments are summarised and the data is displayed in flood hydrographs.
• Wave heights from Wave-rider buoys located at Sydney and Crowdy Head have been summarised to provide insight into the dynamics of the flood.
• A collection of photographs documenting the flooding at different gauges throughout the affected catchments is presented in Appendix B.