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Understanding the timing of river-floodplain wetland connection is critical for anticipating ecological risks, including aquatic fauna strandings. In the wet–dry tropics of northern Australia, these risks may intensify due to climate change and water extraction. We combined Sentinel-2-derived modified normalised difference water index (MNDWI), river stage, and rainfall data to monitor inundation dynamics and connectivity between the Daly River (Australia) and three permanent wetlands that act as refugia for aquatic species. We assess annual flood frequency (2018–2025), monthly inundated area, and their relationships with rainfall and river stage. Data gaps due to cloud cover were gap-filled using a random walk model with Kalman filtering and smoothing. Gap-filled MNDWI enabled the detection of spatiotemporal wetness patterns along transects connecting the wetland to the river. Results reveal large interannual variability in inundation, with 2018–2019 and 2019–2020 exhibiting low persistence and extent of flooding, while 2023–2024 showed widespread and prolonged inundation. Connectivity duration differed among transects (6–112 days). We identify stage thresholds (m) for disconnection as an indicator of river-wetland connectivity, with first disconnection dates varying between February–July, depending on the transect. We also derive three pixel-based hydrological indicators: first wetting day, last drying day, and seasonal duration of wet conditions (days yr −1 ). The strength of relationships between inundation and predictors supports the use of these readily available datasets for forecasting disconnection timing. We provide a practical approach to inform aquatic biodiversity conservation planning measures that can be readily adapted to other floodplain systems. • Wetland connection and disconnection estimateable using remote sensing. • Easily obtainable parameters used in predictive modelling. • MNDWI used to identify critical river stage thresholds for connection/disconnection.
Irvine et al. (Mon,) studied this question.