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Modélisation du ruissellement sur surfaces rugueuses

Abstract : Numerical models, dedicated to runoff and weathering study at watershed scale, consider a friction coefficient to evaluate the surface hydraulic resistance. Both experimental and theoretical studies already gave numerous formulas for these coefficients. However, the most of these formulas has been based on analogies with resistance relationships in pipe flow or turbulent rough boundary open channel flow, with an implicit assumption of micro scale boundary roughness. So, boundary roughness only contributes to hydraulic resistance through friction effect neglecting the hydrodynamics.
Water flows over large scale roughness, naturally occurring in shallow unchannelised land surface flows, make the micro scale boundary roughness assumption unfounded.

To better account for the variable influence of roughness with varying levels of emergence, the present work considers different hydraulic network associated with the surface degree of inundation. Considering a hydraulic model we are able to compute discharge and friction coefficient versus inundation ratio.
As modeller need friction coefficients related to surface characteristic class, we applied our hydraulic model to surfaces randomly generated. Our results demonstrate the roughness spatial distribution effect.
Because of experimental difficulties, we do not have enough experimental results for low inundation ratio to validate our numerical model. Nevertheless we point out transition between partial and marginal inundation is characterized by a sudden discharge increase.
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https://tel.archives-ouvertes.fr/tel-00121568
Contributor : Nicolas Roche <>
Submitted on : Thursday, December 21, 2006 - 10:51:24 AM
Last modification on : Thursday, November 19, 2020 - 3:54:29 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 7:45:28 PM

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  • HAL Id : tel-00121568, version 1

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Nicolas Roche. Modélisation du ruissellement sur surfaces rugueuses. Hydrologie. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00121568⟩

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