Flocculation, a dynamic process that binds fine muddy sediments with organic material in saltwater to form larger porous aggregates, is a fundamental process in estuarine and coastal zones that controls particle settling velocity and the vertical distribution of sediment; hence, it plays an important role in sediment deposition/erosion patterns, light attenuation in the water column, nutrient and carbon cycling, and water quality. To advance the general understanding and predictive capability of coupled flocculation dynamics and sediment transport, this project will integrate field, laboratory, and modeling approaches to address the knowledge gaps in 1) understanding the control of floc size and settling velocity in the estuarine boundary layer and their relationship to bottom shear stress and suspension and deposition; 2) evidence-based model coefficients for a flocculation model that reflects natural mud properties; 3) the relationship between floc size and settling velocity, especially for high organic content environments and muds with varying amounts of silt; 4) computationally efficient yet reliable coupling of flocculation dynamics in coastal models. This study has the potential to transform our ability to understand and include flocculation dynamics in coastal modeling under different levels of primary productivity due to seasonal and spring-neap variability. As such, it will impact broader research communities in biogeochemistry, carbon cycling, ecosystems and water