This report provides the Flood Study component of the floodplain risk management process and details the investigation of flood behaviour associated with the ‘urban’ area of Mungindi. The general area of Mungindi is located on the Barwon River floodplain and has been subjected to various degrees of flooding over the years. The town itself lies on the Carnarvon Highway, 120km Northwest of Moree, straddling the Queensland and New South Wales border. The township supports agricultural (cotton, wheat) and cattle farming industries and has a road link to Moree. Over the years farming levees have been constructed in the Barwon River floodplain with some located within 1.5km of the town. These levees have impacted on the distribution of breakout flows from the river systems, both upstream and downstream of Mungindi. This study has involved the establishment of historic and design storm flows using flood frequency analysis and the set-up of a two-dimensional, dynamic hydraulic model.

The approach undertaken for this flooding investigation has included the following key work items:

1. Identification of areas requiring additional ground survey and collation of this survey with existing photogrammetric data;
2. Site Inspections and Historic Flood Data Gathering;
3. Extraction of discharges and water levels from the existing Border Rivers Mike 11 model for use as boundary conditions in the 2D hydrodynamic modelling of historic events used for calibration purposes.
4. Flood frequency analysis to determine design flows for the 20%, 10% and 1% AEP.
5. Detailed hydraulic modelling of historic flood events for calibration purposes followed by modelling of the design flood events for the AEPs mentioned above.
6. Estimation of the Probable Maximum Flood (PMF) if practical.