The self-organization of step-pools in mountain streams

Chin, Anne; Phillips, Jonathan D.

doi:10.1016/j.geomorph.2006.02.021

Cited by 64 publications

(33 citation statements)

References 53 publications

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“…For example, presented a qualitative conceptual model of landscape evolution in terms of improbable system states, arguing that although deterministic process "laws" act on topography, the actual outcome (i.e., any particular landscape) depends on initial conditions and in particular is sensitive to history. Many other works have similarly generalized complex channel process and response feedbacks to understand morphodynamics (e.g., Fonstad, 2003;Phillips, 2011Phillips, , 2009Phillips, , 1991Chin and Phillips, 2007;Stark and Stark, 2001;Yanites and Tucker, 2010).…”

Section: State Variable Framework For Modeling Morphodynamicsmentioning

confidence: 99%

“…Entropy is the state variable perhaps used most often to characterize channel systems (e.g., Chin and Phillips, 2007;Leopold and Langbein, 1962;Rodriguez-Iturbe and Rinaldo, 1997). Entropy can provide a closure for underconstrained sets of equations, by assuming that geomorphic systems inherently maximize their entropy at equilibrium (Kleidon, 2010;Chiu, 1987).…”

Section: State Variable Framework For Modeling Morphodynamicsmentioning

confidence: 99%

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Gravel threshold of motion: a state function of sediment transport disequilibrium?

Johnson

2016

Earth Surf. Dynam.

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Abstract. In most sediment transport models, a threshold variable dictates the shear stress at which nonnegligible bedload transport begins. Previous work has demonstrated that nondimensional transport thresholds (τ * c ) vary with many factors related not only to grain size and shape, but also with characteristics of the local bed surface and sediment transport rate (q s ). I propose a new model in which q s -dependent τ * c , notated as τ * c(q s ) , evolves as a power-law function of net erosion or deposition. In the model, net entrainment is assumed to progressively remove more mobile particles while leaving behind more stable grains, gradually increasing τ * c(q s ) and reducing transport rates. Net deposition tends to fill in topographic lows, progressively leading to less stable distributions of surface grains, decreasing τ * c(q s ) and increasing transport rates. Model parameters are calibrated based on laboratory flume experiments that explore transport disequilibrium. The τ * c(q s ) equation is then incorporated into a simple morphodynamic model. The evolution of τ * c(q s ) is a negative feedback on morphologic change, while also allowing reaches to equilibrate to sediment supply at different slopes. Finally, τ * c(q s ) is interpreted to be an important but nonunique state variable for morphodynamics, in a manner consistent with state variables such as temperature in thermodynamics.

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Section: State Variable Framework For Modeling Morphodynamicsmentioning

confidence: 99%

Section: State Variable Framework For Modeling Morphodynamicsmentioning

confidence: 99%

Gravel threshold of motion: a state function of sediment transport disequilibrium?

Johnson

2016

Earth Surf. Dynam.

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“…However it has also become evident that chance, through local channel conditions which increase the likelihood of particle jamming, plays a significant role (Curran and Wilcock, 2005;Zimmermann et al, 2010). At the reach scale, regularity in step-pool geometry has been argued to be an emergent property, a result of self-organization towards a more stable channel condition, defined for instance by lower entropy (Chin and Phillips, 2007) or higher overall resistance or stability (Abrahams et al, 1995;Weichert et al, 2008). In reality, field investigations show that the spatial organization of steps in natural streams is not so clear.…”

Section: Introductionmentioning

confidence: 99%

Analysis of changes in the step-pool morphology and channel profile of a steep mountain stream following a large flood

et al. 2010

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“…Step-pools represent an interesting case of spontaneous, self-organized system of high stability (Chin and Phillips, 2007). Their morphological features have inspired the design criteria for artificial check dam sequences in high-gradient streams stabilization (Lenzi, 2002;Wang and Yu, 2007;Chin et al, 2009;Wohl et al in Conesa-García and Lenzi, 2010).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

A conceptual model of check dam hydraulics for gully control: efficiency, optimal spacing and relation with step-pools

Castillo

Pérez

Gómez

2014

Hydrol. Earth Syst. Sci.

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Abstract. There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes within restored gully reaches, despite it being a crucial issue for the design of gully restoration measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and damfilling conditions as well as a method of estimating efficiency in order to provide design guidelines. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump, impact flow, gradually varied flows). Ten main classifications of flow regimes were identified, producing similar results when compared with the IBER model. An interval for optimal energy dissipation (ODI) was observed when the steepness factor c was plotted against the design number (DN, ratio between the height and the product of slope and critical depth). The ODI was characterized by maximum energy dissipation and total influence conditions. Our findings support the hypothesis of a maximum flow resistance principle valid for a range of spacing rather than for a unique configuration. A value of c = 1 and DN ∼ 100 was found to economically meet the ODI conditions throughout the different sedimentation stages of the structure. When our model was applied using the same parameters to the range typical of step-pool systems, the predicted results fell within a similar region to that observed in field experiments. The conceptual model helps to explain the spacing frequency distribution as well as the often-cited trend to lower c for increasing slopes in step-pool systems. This reinforces the hypothesis of a close link between stable configurations of step-pool units and man-made interventions through check dams.

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The self-organization of step-pools in mountain streams

Cited by 64 publications

References 53 publications

Gravel threshold of motion: a state function of sediment transport disequilibrium?

Gravel threshold of motion: a state function of sediment transport disequilibrium?

Analysis of changes in the step-pool morphology and channel profile of a steep mountain stream following a large flood

A conceptual model of check dam hydraulics for gully control: efficiency, optimal spacing and relation with step-pools

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