Estimates of the suspended sediment reference concentration (Ca) and resuspension coefficient (γ0) from near-bottom observations on the California shelf

Near-bottom current and suspended sediment measurements above a sandy clayey silt bed on the California continental shelf are used to estimate the near-bed suspended sediment reference concentration, C_a, and the bed shear stress, τ₀. A proposed model contends that C_a should be proportional to the normalized excess shear stress acting on the sediment grains and to the availability of erodible grains in the bed. The coefficient of proportionality (γ₀) in this model is estimated for 10 erosion events and is found to range from about 1.5 × 10⁻⁵ to 3 × 10⁻⁴. Moreover, the estimated γ₀ values appear to be inversely proportional to the excess bed shear stress. This result suggests that other factors, such as bed armoring and grain cohesion, inhibited the resuspension of particles at the relatively higher shear stresses.