FVCOM SEDIMENT MODEL

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FVCOM SEDIMENT MODEL
Geoff Cowles
06/20/06
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Overview
FVCOM Sediment model is an implementation of the
USGS Community Sediment Model Follows work of
John Warner (USGS) for ROMS
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Bed Layers
Thickness Thickness Change Sediment Fractions Fbi
Porosity Pb Age
bottom
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2
Thickness Age Porosity
3
nbed
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Bed Dynamics

• In a resuspension event, grain size distribution
  is
• modified in surface layer.

• Sediment size distributions are updated to
  reflect
• exchange between active layer and underlying bed
• when the boundary position is altered due to
• erosion/deposition.

- Thickness of surficial layer of active sediment
Proportional to excess flow shear stress.
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Sediment Governing Equation/BC
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Erosion / Deposition
Erosion
Deposition Solve the settling equation using
flux limiters to preserve monotonicity in
sharp gradients Save flux through
bottommost control volume as depositional flux.
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Implementation
Roughly a 1-D Implementation like GOTM.
One way coupling with FVCOM -No modication
of near bottom density field -No
modification of optical field (yet)
Uses Fortran Type to define a sediment -
sediment properties - boundary conditions
- 3D Field - Operators (diffuse,
erode, advect)
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Setup
See manual for details
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Future Modifications
Disclaimer
Sediment Model is untested on realistic
applications.
Modification of Bottom Stress by Surface
Waves Bathymetric Modification - Shoaling Support
for Cohesive Sediments (flocculation, many new,
somewhat arbitrary parameters)