Combined flow-induced bed shear stress and sediment-biologic dynamics in a supratidal flat of the Bahía Blanca Estuary during a positive storm surge
Description
Wave and current data From June 5th to 12th, 2024, at Villa del Mar, a Sontek acoustic Doppler velocimeter (ADV), which measures the three components of velocity (u,v,w) at a given point, was installed on a tetrapod and located 10 cm above the surface of the supratidal flat where the measurement volume is located on that surface. The sampling methodology used was a simple burst sampling strategy, with a data acquisition frequency of 10 Hz, in bursts of 12 minutes, with 30-minute intervals between bursts. The ViewHydra software (Sontek) was then used for the visualization and preliminary analysis of the data. Twenty-one bursts were obtained: 5 bursts on June 6th, 7 bursts on June 7th, and 9 bursts on June 9th, coincident with the moments the sensor was underwater. Data with a correlation coefficient exceeding 80% (a measure of the quality of the ADV velocity data) were employed, which corroborated, with the pressure data in dbar (representing the water level on the flat), that the water had covered the supratidal flat, and the sensor. Nine bursts corresponding to the storm conditions were analyzed, three were measured at flood tide, one at slack tide, and the remaining five at low tide. Then, the data was processed in a specific script. Chlorophyll-a and Phaeopigments To determine the photosynthetic activity in sediments (as a proxy), fifteen samples (5 samples with 3 replicates each: 6 samples on June 5th, 3 samples on June 8th, 3 samples on June 12th, and 3 samples on June 14th) of 1.5 mm thickness of surface sediment were extracted from the supratidal flat. The concentration of chlorophyll-a (Chl-a) and phaeopigments (Phaeop) were determined following the Strickland and Parson (1968) method. Funding for this research came through grants PGI 24/H081 (awarded to DGC) and PGI 24/H138 (awarded to GMEP) from SECyT-UNS and grant Pampa Azul A8 from MINCyT (awarded to DGC). This research is part of Camila Stempels Bautista´s Doctoral Thesis, Geology Department, Universidad Nacional del Sur.