Satellite-Based Inundation Modelling for Large-Scale Wetland Restoration in Semi-Arid Australia

Wetlands, among the world’s most biodiverse and productive ecosystems, face severe threats from flow regime alterations, unsustainable water management, land-use conversion, increasingly exacerbated by climate change. Reduced connectivity between river channels and their floodplain habitats is often a consequence of subsequent drying, significantly degrading ecological health. We investigated the impacts of a century of river regulation and upstream water abstractions on the Lowbidgee Floodplain in semi-arid Australia - a nationally important wetland ecosystem on the lower Murrumbidgee River within the Murray-Darling Basin. This floodplain, which includes the indigenous-managed Gayini Wetlands and Yanga National Park, has a rich Aboriginal cultural heritage and supports a range of threatened and endangered native Australian species. We utilized Landsat and Sentinel satellite data to map wetland inundation patterns from 1988 to the present. Through the analysis of discharge data from the floodplain’s river gauges, we modelled the extent and frequency of wetland inundation under variable water availability scenarios, resulting from river regulation and climate change. Additionally, we evaluated the effects of altered flow and flood regimes on the health of flood-dependent vegetation, using remote sensing-derived vegetation indices such as the NDVI and Fractional Vegetation Cover (FVC). Our study aims to inform environmental flow management for large-scale river and wetland restoration efforts. It also provides the indigenous landowners, the Nari Nari Tribal Council, with crucial data to support their land and water management.