Riverine discharge is a primary vector for terrestrial sediments entering coastal marine ecosystems, forming high‑turbidity plumes that can threaten benthic habitats through chronic light attenuation. The transient nature of these events makes them difficult to quantify using traditional in‑situ monitoring. This study uses a decadal archive (2013–2024) of Landsat 8 optical imagery to map river plume dynamics from nine major estuaries across the New South Wales (NSW) Marine Estate. A physics‑based deep‑learning remote sensing model was applied to generate high‑resolution time series of total suspended solids (TSS), enabling spatially consistent mapping of plume extent and severity. A regional sensitivity analysis identified a robust turbidity threshold (ΔTSS > 10.0) to distinguish active plume waters from marine background conditions.
Results show that the Clarence (158.3 km²) and Shoalhaven (153.5 km²) rivers are the dominant contributors to coastal turbidity. Catchment size alone was a poor predictor of plume extent: the Hawkesbury River, despite its large catchment (>22,000 km²), exhibited a limited marine footprint (35.1 km²), while the Shoalhaven acted as a high‑efficiency exporter of suspended sediments. Temporally, plume activity was lowest during 2017–2019 and elevated during 2020–2022, with northern systems displaying greater inter‑annual variability. These findings establish a regional baseline for assessing exposure of marine habitats to recurrent catchment‑derived turbidity along the NSW coast.