The Ovens River floodplain is one of the many within the Murray-Darling Basin that has been subject to anthropogenic changes, negatively impacting on the condition of floodplain and wetland environmental assets. The lower Ovens River and its floodplain wetlands are in much better condition than many other rivers in the basin due to the absence of major water storages and extractions from the upper catchment, with less impact on the magnitude, frequency and duration of flooding. However it still has a number of issues to manage; namely vegetation clearance, pest species, the operation of the Murray River and backwatering from Lake Mulwala, and the construction of levees, channel banks and roads, some of which have disconnected wetlands from the river.
The Lower Ovens Connectivity Study was a landmark project which integrated complex floodplain hydraulics, catchment hydrology, advanced spatial analysis, ecological assessments and environmental outcomes. Detailed 1D/2D hydrodynamic models were used to understand the flood behaviour across the floodplain at a range of different magnitude flow events. Extensive condition assessments of the significant ecological assets within the floodplain were also conducted. The study identified and mapped over 380 potential barriers to flow and produced a number of highly valuable datasets which relate areas such as wetland connectivity, frequency of wetland inundation and ecological condition that could serve as a benchmark for floodplain managers across the Murray-Darling Basin. The knowledge gained from the study was incorporated into a geodatabase that linked flood behaviour to connectivity and ecological assets within the floodplain.
The study concluded that much of the lower Ovens floodplain is in excellent condition and that there are few barriers which significantly reduce wetland connectivity, with 90% of the wetlands found to be inundated on average at least every two years. The approach developed in this study could easily be applied to other river systems across the country to improve understanding of the ecological condition and connectivity of floodplains and improve management of key environmental assets. The study has developed a number of tools that will significantly expand the North East CMA’s capacity to engage key stakeholders in identifying options for improving the management of unregulated flows to key environmental assets through the design and management of environmental infrastructure.