Gundaroo is located within the Sydney-Canberra Corridor, approximately 220 km south-west of Sydney and 40 km north of Canberra. The township is located within the upper reaches of the Yass River Catchment, at the confluence of the Yass River, McLeod’s Creek and Back Creek. The information and results obtained from this study define existing flood behaviour at Gundaroo and provide a firm basis for the development of a subsequent Floodplain Risk Management Study and Plan (FRMS&P). Primarily, the study was developed in order to meet the objective of defining the flood behaviour (0.2 EY, 10%, 5%, 2%, 1%, 0.5% AEP events and the Probable Maximum Flood) due to both mainstream flooding and major overland flow at Gundaroo and to:

• Investigate the accuracy of the Sutton Stream Gauge rating and liaise with NOW hydrographers;
• Undertake Yass River Flood Frequency Analysis (FFA) at the Sutton Stream Gauge for use in hydrologic model calibration;
• Define flood behaviour in terms of peak flood levels, depths, velocities, flows and flood extents within the study area;
• Prepare flood extent mapping for historic and design events;
• Prepare flood profiles for historic and design events;
• Prepare provisional flood hazard category mapping for the 1% and 0.5% AEP events;
• Prepare provisional hydraulic category mapping for the 1% and 0.5% AEP events;
• Provide a preliminary Flood Planning Area Map (FPA) for mainstream and major overland flow flooding;
• Determine the number of properties flooded over floor in each design event and described flood damage assumptions, details, database and Average Annual Damages; and
• Create a modelling system to be used in the subsequent FRMS&P to test proposed flood mitigation works.