Channel evolution after dam removal in a poorly sorted sediment mixture: Experiments and numerical model

Carles Ferrer-Boix, Juan P. Martín-Vide, Gary Parker

Research output: Contribution to journalArticle

Abstract

Dam removal is commonly used for river restoration. However, there are still some uncertainties associated with dam removal, mainly related to the sediment transport rates released downstream from the deposit that had previously filled the impoundment. This research studies the physical response to dam removal in the antecedent deposit by answering the following questions: (a) how does an initial channel excavated into the deposit evolve, and (b) what is the time distribution of the material released during the early stages of the process. These goals are achieved by an experimental campaign using a poorly sorted mixture of sediment in the antecedent deposit. The research shows that for the given conditions of our experiments, the rate at which the sediment is released depends on the height of the removed dam, the water discharge and the maximum potential volume of sediment to be eroded. This investigation provides new insights of the width evolution when the sediment is composed of a poorly sorted mixture. This evolution is linked to the bed degradation rates: channel narrows during a rapid incisional phase, and subsequently widens when bed degradation rates decrease. Channel width changes propagate upstream as a convection-like perturbation associated with a kinematic wave starting at the location of the antecedent dam. These features are modeled through a new numerical model accounting for mixtures. More specifically, a set of equations has been derived for the variation of bed elevation, channel bottom width, and bed grain-size distribution, which when solved numerically, describe the observed channel processes.

Original languageEnglish (US)
Pages (from-to)8997-9019
Number of pages23
JournalWater Resources Research
Volume50
Issue number11
DOIs
StatePublished - Nov 2014

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dam removal
sediment
experiment
dam
channel change
degradation
impoundment
sediment transport
grain size
kinematics
convection
perturbation
rate
river
water

Keywords

  • dam removal
  • erosional narrowing
  • erosional widening
  • experiments
  • numerical model
  • sediment mixtures

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

Channel evolution after dam removal in a poorly sorted sediment mixture : Experiments and numerical model. / Ferrer-Boix, Carles; Martín-Vide, Juan P.; Parker, Gary.

In: Water Resources Research, Vol. 50, No. 11, 11.2014, p. 8997-9019.

Research output: Contribution to journalArticle

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