Using an ecosystem services approach to re-frame the management of flow constraints in a major regulated river basin

ABSTRACT Worldwide, floodplains have been alienated from river channels for flood protection and water resource development, but several recent programs have restored connectivity, generating considerable ecological and , socio-economic benefits. In Australia, under the Murray-Darling Basin Plan, water purchased from irrigators is used to restore wetlands. Maximising ecological benefits with limited water requires constraints relaxation, whereby high flow volumes for ecologically effective floods are released from headwater dams and allowed to flood public and private land en route to wetlands downstream, requiring infrastructure works and rights to inundate private land. We examined five focal areas in the Basin Constraints Management Strategy to determine ecosystem services benefits generated by floods on land between dams and target wetlands We found multiple examples where significant co-benefits could be realised but had not been identified. Accordingly, the assessment of costs and benefits was primarily focussed on costs. We categorised ecosystem services for each focal area as of low, medium or high importance andassigned monetary values where possible. Regulating and cultural services, rather than provisioning services, ranked highest across all focus areas, including groundwater recharge, regulation of riparian habitat quality, aesthetic appreciation, recreation and tourism, Indigenous and community values. The business cases seek to maximise costs and thus the transfer of public funds in compensation to landholders. However, there are important public policy considerations of equity, accountability and transparency, including proof of damage prior to compensation, as well as offsetting losses against ecosystem services benefits. We consider that an ecosystem services approach could greatly improve acceptance of constraints relaxation amongst landholders and the development of novel policy options and instruments that can help advance the implementation of the Basin Plan.