Predicting flow and vegetation status in floodplain wetlands during drought

Floodplain vegetation of semiarid and arid areas of Australia is dependent on the water availability. In some lower floodplains, the complex interaction between flow and the low gradient topography form unique wetland sites that serve as invaluable refugia for a diverse range of fauna. The biodiversity of these sites is then dependent on the deliveries of environmental water, which competes with other water uses such as crop irrigation and human consumption. In the Murray Darling Basin (MDB), water-sharing plans are developed by regulatory authorities to outline the delivery of environmental flow to different ecological assets. Although environmental water deliveries are targeted to produce the best outcomes for vegetation and other habitat services, definition of water releases and monitoring of these outcomes can be aided by the use of predicting tools that would allow assessing vegetation status. We have developed a detailed hydrodynamic model integrated with vegetation response functions to provide estimates of the expected state of the vegetation. Here we analyze the current state of vegetation in the Macquarie Marshes, a wetland site located on the Macquarie River floodplain, in NSW. Inflows into the site are controlled by water releases from a dam upstream. Recently, drought has affected the region and limited the availability of environmental water as defined in the water-sharing plan. We use our model to evaluate the wetland habitat services by simulating the overall condition of the vegetation and by identifying critical areas within the site.