Narara Creek is a tributary of Brisbane Water and is located to the north of the estuary, within the Gosford Local Government Area. The catchment has a total area of 46.7 square kilometres and drains generally southward. It comprises of seven major sub-catchments (area):

• West Narara Creek (14.3)
• Upper Narara Creek (8.3)
• Fountain Creek (5.1)
• Wyoming Creek (3.1)
• Wingello Creek (4.9)
• Bradys Gully (2.6)
• Lower Narara (8.4)

The objective of this study is to develop a calibrated combined 1D-2D hydraulic model of the whole catchment to define flood behaviour and produce information on flood flows, velocities, levels and extents for a full range of flood events under existing catchment and floodplain conditions, assumed to be representative of fully developed catchment and floodplain conditions.