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# Transport formula

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Hi,

if someone can help me again I will be very happy. I am using the cms-m2d and I am some trouble in assiging the coefficient of Lund cirp or Watanabe formula:

what is meant by "transport slope coefficient" in Lund Cirp and Watanabe formula?

thank you so much

Gio

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• 2 weeks later...
Hi,

if someone can help me again I will be very happy. I am using the cms-m2d and I am some trouble in assiging the coefficient of Lund cirp or Watanabe formula:

what is meant by "transport slope coefficient" in Lund Cirp and Watanabe formula?

thank you so much

Gio

Gio,

This is a difficult parameter to provide hard guidance on because it tends

to

vary site to site. The D slope coefficient is a diffusion coefficient for

increasing downhill transport or decreasing uphill transport (if D is >=1).

It can vary site by site and even within a single site domain in that some

areas have constraints with naturally occurring steep bed slopes (e.g.,

channels) and other areas have gentle slopes (e.g. beach profiles, or tidal

flats). I would like to eventually make this coefficient variable based on

the ratio between bedload to total load. Greater values of D tend to smooth

more (acts as diffusion coefficient).

This is a good parameter to use as a morphology change calibration factor

(along with the scalesus and scalebed coefficients). Unfortunately, what

calibrates for one region of the model may not calibrate well for another,

so

an average value may be necessary.

If you look at page 32 of the Two-Dimensional Depth-Averaged Circulation Model CMS-M2D: Version 3.0, Report 2, Sediment Transport and Morphology Change TR it talks about it a little bit. TR Link

qtotal=q+ D |q| (dh/dx)

You may find out more information if you look at the following:

Karambas, T.V. 2003. "Nonlinear wave modeling and sediment transport in the

surf and swash zone," Advances in Coastal Modeling, V.C. Lakhan (ed.),

Elsevier Oceanography Series, 67, Amsterdam, The Netherlands, 267-298.

Larson, M., Hanson, H., and Kraus, N.C. 2003. "Numerical modeling of beach

topography change," Advances in Coastal Modeling, V.C. Lakhan (ed.),

Elsevier

Oceanography Series, 67, Amsterdam, The Netherlands, 337-365.

Watanabe, A. 1985. "Three-dimensional predictive model of beach evolution

around a structure," Proceedings of International Symposium on Water Wave

Research, University of Hannover, Germany, 121-142.

and Chapter 4 of the following book:

Horikawa, K. 1988. (ed.) "Nearshore dynamics and coastal processes. Theory,

measurement, and predictive models," University of Tokyo Press, Tokyo,

Japan.

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Gio,

Cameron also put together this web page on our help wiki: http://www.xmswiki.com/index.php?title=SMS...atanabe_Formula

Thanks,

John

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I am dealing with watanabe formula and my results are so far from reality: I am getting so low results that I think I calibrate the coefficients of the formula in the worng way.

I read in the link that the transport slope coefficient vary from 5 to 30, is 5 generally used for steep bed slopes and 30 for gentle ones?I understand that values vary site by site but i am just asking to have an idea.

thank you all

...hey, MERRY CHRISTMAS!!!!!!!!!!

gio

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