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Determining Critical Vegetation Conditions in the Macquaire Marshes Using an Eco-Hydraulic Approach

Author(s): Steven G. Sandi, Jose F. Rodiguez, Patricia Saco, Li Wen, Neil Saintilan

Linked Author(s): José Rodríguez

Keywords: Macquarie Marshes, vegetation dynamics, critical plant conditions, fractional coverage

Abstract: The Macquarie Marshes is a freshwater system located in the lowland floodplain of the Macquarie River, in NSW, Australia. As water flow enters the system, water is distributed to a number of swamps and lagoons via a network of anabranching channels. The marshes house unique plant communities that serve as a sanctuary for many species of migratory waterbirds, fisheries and other types fauna. In the past decades, a significant deterioration in plant communities has been observed due to a reduction of the input discharges to the marshes for industrial, agricultural and domestic usage. In recent years, there has been a slow recovery of some areas of the site which has been accomplished by delivering controlled environmental flows from an upstream dam. However, computational tools are required in order to provide a better assessment of watering strategies. In this publication we analyze the evolution of six vegetation patches by implementing a combination of green fractional cover and minimum inundation over a series of 23 years. We simulate floods by implementing a quasi-2D hydrodynamic model over a rectangular cell grid and combine the results. This approach allowed to determine critical watering conditions leading to a transition from understory wetland vegetation (Common Reed and Water Couch) to terrestrial species as well as minimum inundation required to trigger a recovery. Our approach also revealed that watering thresholds for understory species may be used as an indicator of critical conditions for River Red Gum


Year: 2017

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