Barellan is located in the Riverina region of south-west NSW. The closest city is Griffith located approximately 50 km to the west. The town of Ardlethan lies some 30 km to the east. The Mirrool Creek floodplain, south of Barellan, is wide and flat, with typical field grades of approximately 0.1%.
Major floods have occurred within the region throughout history. A number of floods have been experienced in the study catchment since European settlement and the construction of the downstream irrigation system in 1912. Major floods are known to have occurred in 1928, 1931, 1939, 1956, 1974, 1984, 1989, and most recently in 2012. Of these flood events only the recent March 2012 event resulted in flooding to Barellan township.
The primary objective of the Flood Study is to define the flood behaviour within the Mirrool Creek catchment, with a particular focus on Barellan, through the establishment of appropriate numerical models. The study has produced information on flood flows, velocities, levels and extents for a range of flood event magnitudes under existing catchment and floodplain conditions. Specifically, the study incorporates:
- Compilation and review of existing information pertinent to the study and acquisition of additional data including survey as required;
- Undertaking a community consultation and participation program to identify local flooding concerns, collect information on historical flood behaviour and engage the community in the ongoing floodplain risk management process;
- Development and calibration of appropriate hydrologic and hydraulic models;
- Determination of design flood conditions for a range of design events including the 20% Annual Exceedance Probability (AEP), 10% AEP, 5% AEP, 2% AEP, 1% AEP, 0.5% AEP and extreme flood event;
- Hydraulic and provisional hazard categorisation of the floodplain to guide future floodplain management; and
- Presentation of study methodology, results and findings in a comprehensive report incorporating appropriate flood mapping.
