Sugarloaf Creek

Overview of Sugarloaf Creek Flood Study

The NSW State Government’s Flood Policy addresses existing flooding problems in developed areas and aims to ensure that new development is compatible with the flood hazard and does not create additional flooding problems in other areas.

The Flood Study constitutes the first stage of the Floodplain Risk Management process for the Sugarloaf Creek catchment and has been prepared for Willoughby City Council, with the financial assistance of the Department of Environment, Climate Change and Water, to define flood behaviour under current conditions.

The purpose of the study was to define flood behaviour on Sugarloaf Creek in terms of water levels, flows and velocities for a range of floods including the 1 in 100 year event. The flood study involved the following activities:

• The collection of flood related data. A Community Newsletter/Questionnaire introducing the study objectives and seeking information on historic flood patterns was forwarded to residents in the floodplain. Three significant storms which had occurred over the past 25 years were identified (5 August 1986, 30 April 1988 and 10 April 1998) and their rainfalls used to test the computer-based flood models developed for the study.
• Preparation of models of the natural surface of the catchment and underground stormwater drainage system, including the main arm of the creek and its overland flow paths. The models extended from the headwaters of the catchment (to the west of Bales Park) to approximately 300 metres downstream of the Eastern Valley Way.
• Presentation of study results as water surface profiles, as well as diagrams showing indicative extents of inundation, provisional flood hazard (based on depth and velocity of overland flows) and the hydraulic categorisation of the floodplain into floodway and flood fringe areas.
• Sensitivity studies to assess the effects on flooding resulting from partial blockage of the piped drainage system and future climate change.

Maps can be viewed below:

•  Sugarloaf Creek - Catchment Plan and Stormwater Drainage System - 6,052 KB
•  Sugarloaf Creek - Provisional Flood Hazard Diagram - 100 Year ARI - 6,256 KB
•  Sugarloaf Creek - High Street to Eastern Valley Way - 100 Year ARI - 2,321 KB
•  Sugarloaf Creek - High Street to Eastern Valley Way - 20 Year ARI - 2,310 KB
•  Sugarloaf Creek - High Street to Eastern Valley Way - 5 Year ARI - 2,148 KB
•  Sugarloaf Creek - Stanley Street to High Street - 100 Year ARI - 2,146 KB
•  Sugarloaf Creek - Stanley Street to High Street - 20 Year ARI - 2,233 KB
•  Sugarloaf Creek - Stanley Street to High Street - 5 Year ARI - 2,114 KB