The properties of particles in surface waters are especially important for the fate of incident light, with direct ramifications for primary production, habitat and water quality, and optical remote sensing. The rate of absorption and scattering of light depends directly on the particle size, composition, and density (Bowers et al., 2011) and indirectly on the particle settling rate, which controls how long and how high in the water column particles remain in suspension (Friedrichs et al., 2008). In the York River estuary and the adjacent Chesapeake Bay, the period of 1985-2016 was marked by a significant long-term decrease in water clarity as measured by the Secchi depth (Murphy et al., 2019). Gallegos et al. (2011) showed via optical modeling that the systematic decrease in Secchi depth in the Chesapeake Bay since the 1980s was likely due to an increase in the abundance of small, organic-rich suspended particles in the estuarine surface waters. The study of the York River estuary presented in the present paper was motivated in large part by a need to better understand the effects of organic matter content on the properties of particles in surface water due to the key role of organic-rich suspensions in affecting the water clarity in estuarine environments.

No abstract

Abstract:The Community Sediment Transport Modeling System (CSTMS) cohesive bed sub-model that accounts for erosion, deposition, consolidation, and swelling was implemented in a three-dimensional domain to represent the York River estuary, Virginia. The objectives of this paper are to (1) describe the application of the three-dimensional hydrodynamic York Cohesive Bed Model, (2) compare calculations to observations, and (3) investigate sensitivities of the cohesive bed sub-model to user-defined parameters. Model results for summer 2007 showed good agreement with tidal-phase averaged estimates of sediment concentration, bed stress, and current velocity derived from Acoustic Doppler Velocimeter (ADV) field measurements. An important step in implementing the cohesive bed model was specification of both the initial and equilibrium critical shear stress profiles, in addition to choosing other parameters like the consolidation and swelling OPEN ACCESSJ. Mar. Sci. Eng. 2014, 2 414 timescales. This model promises to be a useful tool for investigating the fundamental controls on bed erodibility and settling velocity in the York River, a classical muddy estuary, provided that appropriate data exists to inform the choice of model parameters.