The Challenge

The New South Wales State Government is reforming water policy in rural areas of the Murray Darling Basin (MDB) to include the NSW Floodplain Management Policy and the NSW Floodplain Harvesting Policy. To support these policy reforms the Office of Environment and Heritage (OEH) is developing five Valley Wide Floodplain Management Plans (VWFMP) across northern valleys of the MDB where floodplain harvesting is widespread. Flood models are a key tool to guiding decisions around balancing environmental flows and harvesting allocations for each of the VWFMPs. The key challenge was to estimate flood levels and discharges along the Barwon-Darling River from Mungindi to Calmundi Weir including its tributaries whilst taking into account breakout flows.

Approach and Outcomes

A flexible mesh MIKE FLOOD hydraulic model of the Barwon-Darling Valley was developed between Mungindi and Calmundi Weir. In-house tools were also developed as part of the project to streamline the model build process and automate the post-processing of results. OEH received a comprehensive set of flood level, depth and depth velocity product maps for a range of modelled scenarios to support the Barwon-Darling VWFMP.