Labs WMT ROMSLIte SettlingRates

Introduction to Regional Ocean Modeling - Settling Rates and Shear Stress

This lab has been designed and developed by Courtney Harris and Julia Moriarty, Virginia Institute of Marine Sciences, Gloucester Point, VA
with assistance of Irina Overeem, CSDMS, University of Colorado, CO

Classroom organization
This is the second lab in a mini series to introduce the Regional Ocean Modeling System (ROMS) for inexperienced users. ROMS is a three-dimensional hydrodynamic ocean model. It solves the conservation of mass and 3D momentum equations and includes transport equations for temperature and salinity. Here we present a basic configuration of ROMS in the framework of the Web Modeling Tool (WMT), it is designed for inexperienced modelers and simulates a river plume affecting the coastal ocean and sediment transport.
This lab focuses on sediment settling rates and shear stress. Basic theory on settling rates and suspended sediment is presented in these slides File:ROMS Lite Introduction.pptx.
This lab will likely take ~ 3hours to complete in the classroom.
If you have never used the Web Modeling Tool, learn how to use it here. The WMT allows you to set up simulations, but once you are ready to run them, you will need an account on the CSDMS supercomputer to submit your job. More information on getting an account can be found here HPCC Access. Note that getting permission for access takes a few days after your application.

Learning objectives

familiarize with a basic configuration of the Regional Ocean Modeling System
learn how to manipulate parameters in ROMS-Lite and set up different experiments

physics of settle rates
fluid exerting stress and threshold to incipient motion
Shields and Yalin diagrams

Lab Notes

>> Open a new browser window and open the Web Modeling Tool here and select the ROMS project
>> This WMT project is unique in that there is only a single driver, ROMS-Lite. It is a pre-compiled instance of the larger ROMS system specially configured for teaching use.

Sediment suspended in the water column is transported, like other conservative tracers (e.g., salinity) by solving the advection–diffusion equation with a source/sink term for vertical settling and erosion. The ROMS model represents sediment using separate cohesive and non-cohesive categories, in this ROMS-Lite model there are 3 non-cohesive sediment classes, and one non-cohesive sediment class. Each class has fixed attributes of grain diameter, density. In WMT settling velocity, critical shear stress for erosion, and erodibility constant. These properties are used to help determine the bulk properties of each bed layer.

References

Warner, Sherwood, Signell, Harris, and Arango, 2008 "Development of a three-dimensional, regional, coupled wave, current, and sediment-transport model", Computers & Geosciences.
Threshold of sediment motion under unidirectional currents, M. C. Miller, I. N. McCave, P. D. Komar, Sedimentology (1977) 24, 507-527.