Migración de una unidad de banco y depositación en el canal del banco: impactos en la conductividad hidráulica y la heterogeneidad del tamaño del grano en un lecho de río arenoso

Translated title of the contribution: Unit-bar migration and bar-trough deposition: impacts on hydraulic conductivity and grain size heterogeneity in a sandy streambed

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The hydrologic function of riverbeds is greatly dependent upon the spatiotemporal distribution of hydraulic conductivity and grain size. Vertical hydraulic conductivity (Kv) is highly variable in space and time, and controls the rate of stream–aquifer interaction. Links between sedimentary processes, deposits, and Kv heterogeneity have not been well established from field studies. Unit bars are building blocks of fluvial deposits and are key to understanding controls on heterogeneity. This study links unit bar migration to Kv and grain size variability in a sand-dominated, low-sinuosity stream in Nebraska (USA) during a single 10-day hydrologic event. An incipient bar formed parallel to the thalweg and was highly permeable and homogenous. During high flow, this bar was submerged under 10–20 cm of water and migrated ~ 100 m downstream and toward the channel margin, where it became markedly heterogeneous. Low-Kv zones formed in the subsequent heterogeneous bar downstream of the original 15–40-cm-thick bar front and past abandoned bridge pilings. These low-Kv zones correspond to a discontinuous 1-cm layer of fine sand and silt deposited in the bar trough. Findings show that Kv heterogeneity relates chiefly to the deposition of suspended materials in low-velocity zones downstream of the bar and obstructions, and to their subsequent burial by migration of the bar during high flow. Deposition of the unit bar itself, although it emplaced the vast majority of the sediment volume, was secondary to bar-trough deposition as a control on the overall pattern of heterogeneity.

Translated title of the contributionUnit-bar migration and bar-trough deposition: impacts on hydraulic conductivity and grain size heterogeneity in a sandy streambed
Original languageSpanish
Pages (from-to)553-564
Number of pages12
JournalHydrogeology Journal
Volume26
Issue number2
DOIs
StatePublished - Mar 1 2018

Keywords

  • Groundwater/surface-water relations
  • Heterogeneity
  • Sedimentology
  • USA

ASJC Scopus subject areas

  • Water Science and Technology
  • Earth and Planetary Sciences (miscellaneous)

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