Variability and forcings of high turbidity events in the northern Adriatic sea from analysis of in-situ long-term data: A methodological approach

Long-term data series (2012–2021) of physical and oceanographic parameters at the LTER-Italy research site “Delta del Po and Costa Romagnola’’, encompassing the Po river delta and the surrounding coastal areas, were analyzed to investigate the variability of surface turbidity in the North-Western Adriatic shelf. This shallow coastal environment is characterized by high river runoff, strong variability in wind regimes (direction and speed) and sea state (wave height). Both meteorological and oceanographic factors drive the local pattern of surface turbidity. This study focuses on an in-situ data analysis to recognize the main forcing responsible for high surface turbidity events (HTEs) along the coastal area. The dataset analyzed combines surface optical turbidity and salinity data, along with meteorological, hydrographic, and wave data from fixed point observing systems. While the main and most intense turbidity events (NTU > 10) in the Po Delta area are primarily caused by suspended sediments from river floods and wind-driven resuspension events, the high correlation between turbidity and wave height indicates that waves are primary driving factors along the Emilia-Romagna coast southward. The results from this study provide a methodological approach based on thresholds and proxies of physical parameters for quantifying variations of HTEs and identifying their main forcing in coastal areas.