Enhancing river flows v. environmental engineering as contrasting approaches to wetland conservation in the Murray-Darling Basin, Australia

Context In regulated river basins, wetland conservation has focussed on managed environmental flows to achieve outcomes. Two approaches have emerged, one based on ecological principles, the other on environmental engineering.Aims To compare these approaches, as applied in the southern Murray-Darling Basin, namely, the Constraints Management Strategy (CMS), based on reducing constraints on within-channel flows to enable flooding of wetlands, and the Victorian Murray Floodplain Restoration Project (VMFRP), based on infrastructure to divert water onto floodplains.Methods We used data from official reports to derive flood frequency, duration and extent and compare economic costs and water use.Key results At five wetlands along the Murray River, CMS and VMFRP achieved similar flood frequency and duration. CMS achieved similar or greater flood extent except at two of five sites and required no clearance of floodplain trees. CMS was almost 10 times cheaper to implement and with lower water price per hectare.Conclusions There was no clear economic or environmental advantage to implementing VMFRPs, given that CMS will be implemented under water reforms in the Murray-Darling Basin Plan.Implications We consider there is a strong case for the Victorian government to reconsider the need to implement the VMFRPs.