A regularization strategy for modeling mixed-sediment river morphodynamics

Chavarrías, Víctor; Stecca, Guglielmo; Siviglia, Annunziato; Blom, Astrid

doi:10.1016/j.advwatres.2019.04.001

Cited by 10 publications

(37 citation statements)

References 104 publications

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“…In section , we have shown that the SILKE model is well‐posed, a property shared with the regularized model (Chavarrías, Stecca, et al, ). Here we clarify why, although being totally different approaches, both the SILKE model and the regularized model yield well‐posed problems.…”

Section: Discussionmentioning

confidence: 91%

“…A laboratory experiment conducted under conditions in which the active layer model is ill‐posed shows that the situation is unstable (Chavarrías, Stecca, et al, ). This instability mechanism is captured by the SILKE model only.…”

Section: Discussionmentioning

confidence: 99%

“…Fine sediment was again available for entrainment as degradation continued, which caused the periodic formation of large bedforms superimposed on the original ones. We refer to Chavarrías, Stecca, et al () for an in‐depth analysis of this experiment.…”

Section: Model Applicationmentioning

confidence: 99%

“…In order to solve for this first limitation and recover well‐posedness of the active layer model, Chavarrías, Stecca, et al () proposed a regularization strategy. The strategy is based on identifying the locations at which the active layer model is ill‐posed and locally modifying the celerity at which mixing processes occur.…”

Section: Introductionmentioning

confidence: 99%

“…Ill-posedness is a symptom of a model not capturing key physical elements (Fowler, 1997;Joseph & Saut, 1990). In our context, the active layer model is ill-posed when key mixing processes that are not included in the model become relevant and the model is incapable of reproducing the actual mixing occurring in nature (Chavarrías, Stecca, et al, 2019). This occurs mainly under degradational conditions and if the active layer is coarser than the substrate (i.e., when modeling degradation of an armored river) (Chavarrías et al, 2018;Ribberink, 1987; In order to solve for this first limitation and recover well-posedness of the active layer model, Chavarrías, Stecca, et al (2019) proposed a regularization strategy.…”

Section: Introductionmentioning

confidence: 99%

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A Well‐Posed Alternative to the Hirano Active Layer Model for Rivers With Mixed‐Size Sediment

2019

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The active layer model (Hirano, 1971) is frequently used for modeling mixed‐size sediment river morphodynamic processes. It assumes that all the dynamics of the bed surface are captured by a homogeneous top layer that interacts with the flow. Although successful in reproducing a wide range of phenomena, it has two problems: (1) It may become mathematically ill‐posed, which causes the model to lose its predictive capabilities, and (2) it does not capture dispersion of tracer sediment. We extend the active layer model by accounting for conservation of the sediment in transport and obtain a new model that overcomes the two problems. We analytically assess the model properties and discover an instability mechanism associated with the formation of waves under conditions in which the active layer model is ill‐posed. Numerical simulations using the new model show that it is capable of reproducing two laboratory experiments conducted under conditions in which the active layer model is ill‐posed. The new model captures the formation of waves and mixing due to an increase in active layer thickness. Simulations of tracer dispersion show that the model reproduces reasonably well a laboratory experiment under conditions in which the effect of temporary burial of sediment due to bedforms is negligible. Simulations of a field experiment illustrate that the model does not capture the effect of temporary burial of sediment by bedforms.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Model Applicationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%