Mudflat Creek is a 123 hectare catchment which drains to Hardys Bay through the lower Killcare
district (refer Figures 1 and 2). The lower section of the catchment is predominantly occupied
by urban residential development. A natural escarpment divides the lower section of the
catchment from the upper plateau area. This upper plateau is predominantly natural or rural
land type with some residential development around Stewart Street, The Scenic Road and
Wards Hill Road (Figure 2).
In light of reported flooding incidents in the study area, and following on from the Killcare
Catchment Drainage Investigation that was completed in 1999 (Reference 1), Gosford City
Council engaged Webb, McKeown & Associates to undertake a Flood Study.
The primary objectives of this Flood Study are:
- to define the flood behaviour of the Mudflat Creek catchment by quantifying flood
levels, velocities and flows for a range of design flood events under existing catchment
and floodplain conditions,
- to assess the hydraulic categories and undertake provisional flood hazard mapping in
accordance with the NSW Floodplain Development Manual 2005 (Reference 2),
- to assess the extent of the flooding problem by undertaking a flood damages
assessment,
- to formulate suitable hydrologic and hydraulic models that can be used in a
subsequent Floodplain Risk Management Study.
As directed by Council, the scope of this study is such that:
- the extent of the hydrologic model covers the entire Mudflat Creek catchment draining
to Brisbane Water,
- the hydraulic model incorporates Mudflat Creek from Brisbane Water to a point
approximately 100 m upstream of Fraser Road,
- in establishing the hydraulic model and appropriate boundary conditions, consideration
has been made of the impacts of tides and Brisbane Water flooding on the Mudflat
Creek catchment.
This report details the results and findings of the Flood Study investigations, the key elements
of which include:
- a summary of available flood related data,
- calibration of the hydrologic and hydraulic models,
- definition of the design flood behaviour for existing conditions through the analysis and
interpretation of model results.
