Managing environmental flows in an agricultural landscape: the Lower Gwydir floodplain

Abstract

The Lower Gwydir floodplain is recognised for its high-conservation value as aquatic plant and wildlife habitat. This, along with the significance of the terminal wetland areas for water bird breeding, has resulted in parts of the floodplain being listed in the late 1990s under the international Ramsar Convention. However, construction of Copeton Dam upstream in the mid 1970s and subsequent changes to the region's irrigation, grazing and cropping industries has altered flow patterns into the wetlands and placed other pressures on the wetlands and their biodiversity values. The Gwydir Regulated River Water Sharing Plan was developed in the early 2000s, in part to counter further wetland degradation and to establish an allocation balance between consumptive and environmental needs. A broad stakeholder committee (the Gwydir Environmental Contingency Allowance Operations Advisory Committee; ECAOAC), currently administered through the NSW Department of Environment, Climate Change and Water, is the primary mechanism by which the subsequent flow allowance is used for environmental benefit. It is the overarching aim of the present study to determine the ecological responses to flow variability in the Lower Gwydir aquatic ecosystem, and to provide the ECAOAC with a model to guide the effective management of flows to maximise ecological responses in this system. The listing of wetlands on "Old Dromana", "Crinolyn", "Goddard's Lease" and "Windella" with the Ramsar Convention will continue to be a major driver of delivering environmental flows into the Lower Gwydir floodplain.