Yass is located in the Southern Tablelands of NSW approximately 240 km south west of Sydney and 50 km NNW of Canberra in the Yass Valley Council Local Government Area. The township straddles the Yass River and is situated immediately downstream of the Yass River Dam and 40 km upstream of Burrinjuck Dam.
The Yass Flood Study was developed in order to define design flood behaviour at Yass due to both mainstream flooding and major overland flow. This included:
- Investigate the accuracy of the Yass Stream Gauge rating and liaise with NOW hydrographers;
- Undertake Flood Frequency Analysis (FFA) incorporating data from the Yass Stream Gauge and Railway Gauge at Yass as well as information prior to the official period of record;
- 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 describe flood damage assumptions, details and Average Annual Damages (AAD); and
- Create a modelling system suitable for use in the subsequent FRMS&P for assessment of proposed flood mitigation works.
