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The quantification and monitoring of sediment dynamics in estuaries has received plenty of attention in recent years due to both economic and environmental interests. Numerical models have been widely applied for predicting the morphodynamic evolution of these areas. However, the degree of uncertainty of these models is often very high due to the lack of measurements necessary for a complete model calibration and validation. In this paper, different methods have been integrated to overcome these limitations. The hydrodynamics and suspended sediment transport in the IJzer estuary were estimated by means of field data and with the use of a two-dimensional hydrodynamic model coupled to a morphodynamic model. Tidal pumping was recognized as the main driving mechanism of sediments inside the estuary. Erosion-deposition areas calculated with the numerical model were compared to the locations and volumes of dredged material. Model results and measurements were generally in good agreement. Additional support for the morphodynamic model results came from airborne hyperspectral images acquired in 2001 and 2005. DOI: 10.1061/(ASCE)0733-950X(2009)135:4(176) CE Database subject headings: Estuaries; Suspended sediment; Numerical models; Measurement; Remote sensing.

Eulerian equations for the vertical flux and momentum of suspended particles in dilute sediment-laden open-channel flow in equilibrium have been derived using the two-fluid approach. Reynolds averaging has been applied in order to allow validation of individual terms with experimental data. Consideration of the various terms of the vertical momentum balance with experimental flume data indicates that the drag force has to be separated into a mean and a turbulent contribution with different timescales, respectively, the (gravitational) particle timescale and the integral turbulence timescale. The resulting formulation further provides a new theoretical closure for the turbulent Schmidt number. DOI: 10.1061/(ASCE)0733-9429(2008) 134:9(1225) CE Database subject headings: Suspended sediments; Open channel flow; Turbulence; Two-phase flow.

The equation derived by Yigong Li and Ashish J. Mehta for determining the hindered settling speed of flocs in mudlike sediment suspensions and the three sets of experimental data they used to validate the equation are problematic. One problem with the equation is the discrepancies that result when it is applied to rigid noncohesive particles. One problem with their validation procedure is that model parameters were determined first by least-squares fitting of the same experimental data.

The article focuses on the vertical mixing in the unstable layer of sediment-loaded open-channel flow. It states that the time between opposite fluctuations is short to set up a steady velocity. Field data for integral timescales are also presented, as well as the particle turbulent fluctuations. It emphasizes that exponential closures are only useful for shallow channel flows, and adds that a Rousean concentration profile should be used for approximation of deep-water scales.

A correction to the article "Vertical Mixing in the Fully Developed Turbulent Layer of Sediment-Laden Open-Channel Flow" in the September 2008 issue is presented.