Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Wednesday, February 14, 2001, Time: 11:15:00 AM

Location: Ruidoso/Pecos

Fries, J, S, Woods Hole Oceanographic Institution, Woods Hole, USA, fries@whoi.edu

Trowbridge, J, H, Woods Hole Oceanographic Institution, Woods Hole, USA, jtrowbridge@whoi.edu

Madsen, O, S, Massachusetts Institute of Technology, Cambridge, USA, osm@mit.edu

ENHANCEMENT OF FINE-PARTICLE DEPOSITION TO PERMEABLE SEDIMENT BEDS

The deposition rate of fine particles is a critical measure of organic matter delivery to sandy environments. Rates greater than the settling velocity occur if particle-laden flows across the sediment-water interface exist. Flume experiments were conducted to test a deposition model combining interfacial diffusion and settling. Deposition rates to flat impermeable beds were equal to settling alone. Enhanced deposition rates were observed to flat sand beds. The measured deposition rates were independent of particle size, supporting the assertion that fluid transport was responsible for enhancing deposition. Small enhancements to coarser sediments were attributed to poor bed filtration. Depending on bed shear stress and grain size, interfacial flows could generate a slip velocity. Slip at the interface reduces shear in the overlying flow and, consequently, the channel drag coefficient. The correlation between experimental drag coefficients and deposition rates was negative, consistent with the proposed model. A positive trend would be predicted by a model where interfacial flows were induced by bed topography. This study identifies interfacial diffusion as another mechanism for enhancement of deposition to permeable sediment beds.

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

Quicklinks