The effect of wet season river flows on flood plume distribution across northern Australia; contribution to coastal productivity, and future extent under climate change
Cartwright, Paula, Genson, Allyson, and Waltham, Nathan (2025) The effect of wet season river flows on flood plume distribution across northern Australia; contribution to coastal productivity, and future extent under climate change. Regional Studies in Marine Science, 89. 104307.
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Abstract
Northern Australia is home to some of the world’s most expansive and ecologically significant river systems, including the Flinders, Gilbert, and Daly Rivers. These river catchments, which drain into the Gulf of Carpentaria and the Timor Sea, are vital to both the health of the region’s estuaries, coastal ecosystems and its commercial fisheries. This study investigates the relationship between wet season river flows, flood plume extent, and primary productivity in adjacent coastal seas, with a focus on understanding potential impacts from climate change and water extraction on these dynamics. Hydrological data from 2003 to 2023 was analysed for the Flinders, Gilbert, and Daly Rivers to determine peak flow events and their corresponding flood plume sizes using MODIS satellite imagery. The study found that flood plumes were highly variable across the 20-year period, with significant events recorded in 2019 and 2023 and strong relationships between 7-day river flows and plume extents for all rivers. Chlorophyll-a concentration, as a proxy for primary productivity, was significantly associated with plume sizes in the southern Gulf of Carpentaria and Anson Bay, specifically for tertiary plumes from the Flinders, Gilbert, and Daly Rivers. Future climate projections indicate potential reductions in rainfall by 2070–2099, which could lead to decreases in flood plume extent and associated primary productivity. This research highlights the critical connection between river flows, coastal flood plumes, and marine productivity in northern Australia. The findings underscore the importance of maintaining environmental water flows to sustain coastal ecosystems and fisheries, particularly in the context of increasing water allocation pressures and the potential impacts of climate change on regional rainfall patterns.