TURBIDITY PATTERNS IN A TIDAL SOUTH ATLANTIC ESTUARY: A REMOTE SENSING APPROACH

ARENA, MAXIMILIANO; PRATOLONGO, PAULA; VITALE, ALEJANDRO JOSÉ; CELLERI, CARLA; DELGADO, ANA LAURA

Simposio; VIII International Symposium on Marine Sciences 2022 (ISMS); 2022

The distribution of Suspended Particulate Matter (SPM) in coastal areas often responds to the interaction of several agents that create a large spatiotemporal heterogeneity in turbidity. This work combines single-point measurements with a time series of satellite turbidity derived from Landsat8-OLI images to provide a first synoptic overview of the main hydrometeorological drivers of turbidity patterns in the Bahía Blanca Estuary (Argentina). The atmospheric correction algorithm based on the black-pixel assumption, using the two OLI-SWIR bands (Vanhellemonth&Ruddick, 2014) and the semi-empirical single band turbidity retrieval algorithm proposed by Dogliotti et al., (2015) were validated using field values of turbidity and applied to all the available Landsat 8-OLI scenes (2013-2021) to produce a time series of satellite turbidity maps. Then, the effects of tides, winds, and rainfall on satellite turbidity were evaluated through Generalized Linear Models built for the outermost zone of the estuary. Cumulative rainfall had negligible effects on turbidity. Around the mouth of the estuary, turbidity responds entirely to winds and were not affected by tidal current speeds or tidal phase. Strong winds within 24 hours before image acquisition time had the greatest influence on turbidity. Winds from all directions except E/NE/N were associated with higher turbidity values, and the effect was significant for winds blowing from the NW. Surface currents produced by winds blowing from the NW, aligned with the azimuth of the channel, aid to the export of estuarine sediments to the shelf and reduce the residence time of the estuary. Therefore, while tides might control erosional processes in the inner section, wind-induced sediment resuspension and export would be critical for the sedimentary budget of the estuary. This work reveal the potential of time series of ocean color products derived from high spatial resolution sensors to resolve turbidity patterns over narrow coastal areas.