The Allans Creek catchment has an area of 42 square kilometres. The catchment lies to the south west of the Wollongong CBD and rises up to the Illawarra escarpment. The catchment is characterised by steep upper slopes with little development and a floodplain with a mix of residential, commercial and industrial development. The objectives of the Flood Study were to:

• define existing flood behaviour for the mainstream flooding in the catchment.
• define design flood levels, velocities and flow distributions for the catchment.
• map the extent of flooding for the 100, 50, 20, 10 and 5 year ARI floods and the Probable Maximum Flood (PMF) for the catchment.