Tidal variability induced cohesive sediment dynamics: Insights into near‐bottom flocculation, settling, and transport processes in a microtidal estuary

Abstract Tidal hydrodynamics influence mud suspension, flocculation, and particle settling behaviors, which are essential to sediment transport, nutrient cycling and morphological evolution in estuarine systems. This study examines near‐bottom floc dynamics in a microtidal estuary under contrasting spring and neap tides, integrating field observations with advanced analytical techniques. Data from multiple field‐deployed instruments were analyzed using a multi‐peak fitting method to characterize particle size distributions, suspended floc characteristics, and dynamics. Spring tides, characterized by strong turbulence and minimal salinity stratification, resulted in dynamic transitions between microflocs and macroflocs, producing loose floc structures (fractal dimension ~ 1.77), faster settling velocities (~ 1 mm s −1 ), and elevated sedimentation flux (~ 0.092 g m −2 s −1 ). In contrast, neap tides exhibited weaker flows and pronounced salinity stratification, favoring gradual aggregation of flocculi and microflocs into compact flocs (fractal dimension ~ 2.25) with slower settling velocities (~ 0.57 mm s −1 ) and reduced sedimentation flux (~ 0.0182 g m −2 s −1 ). Suspended sediment concentration, turbulent shear and salinity emerged as key drivers, influencing floc size, volume and aggregation processes. These findings refine the understanding of cohesive sediment transport in tidally influenced estuaries and provide process‐based parameters for improved morphodynamic and biogeochemical modeling in nature.