An Integrated Hydrodynamic-Sedimentologic-Morphologic Model for the Evolution of Alluvial Channels Cross-Sections

Abstract

A practical implementation of an integrated hydrodynamic-sedimentologic-morphologic model for the evolution of the cross section of an alluvial channel is presented. It is shown that the driving hydrodynamics can be solved through a series of concatenated 1D hydrodynamic models, which reduces the mathematical complexity to its minimum. A mechanistic model for bed load transport is presented, which can be used readily by practitioners. As part of the morphologic model, a sliding algorithm is proposed to limit the lateral slope which, in particular, efficiently deals with non-cohesive bank erosion. The obtained integrated model is validated by comparing its results with experimental data and previous calculations for evolving channel cross sections. The comparison shows good agreement between these data and the numerical results. To illustrate the model capabilities, numerical experiments are performed on open channels with different radii of curvature to attain stabilized cross-section forms.

Numerical prediction of morphological change of straight trapezoidal open-channel

“…The lateral distribution model is used for flow prediction, and the vectorial formula proposed by Kovacs and Parker (1994) was used for the estimation of bedload transport. Exner's equation was solved to update the channel shape with the help of the sliding algorithm by Menendez et al (2008).…”

“…Menendez et al (2008) referred to this formula as a mechanistic model because empirical contents are only present at the force parameterization level. Kovacs and Parker's (1994) formula takes the following form:…”

“…In the present study, the sliding algorithm proposed by Menendez et al (2008) is used. That is, at each time step, the lateral slope between two nodes is calculated.…”

“…The lateral distribution model is used to compute the unit discharge over the channel width, and Kovacs and Parker's (1994) formula is used to estimate the bedload. Exner's equation is solved to update the channel shape with the help of sliding algorithm proposed by Menendez et al (2008). Important parameters such as roughness coefficient and eddy viscosity are calibrated.…”

Bottom changes in coastal areas with complex shorelines

“…Many authors (Kalinske, 1947;Karambas & Koutitas, 2002;Menéndez, Laciana, & García, 2008;Murillo & García-Navarro, 2010) have used the Exner equation for bottom change simulations: in this equation, the bottom time variations are expressed as a function of the long-shore and cross-shore variations of the bed load and suspended sediment load. The Exner equation admits the hypothesis that only the hydrodynamic local conditions drive the suspended sediment load.…”