Development of layered sediment structure and its effects on pore water transport and hyporheic exchange

Aaron I. Packman*, Andrea Marion, Mattia Zaramella, Cheng Chen, Jean François Gaillard, Denis T. Keane

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Hyporheic exchange is known to provide an important control on nutrient and contaminant fluxes across the stream-subsurface interface. Similar processes also mediate interfacial transport in other permeable sediments. Recent research has focused on understanding the mechanics of these exchange processes and improving estimation of exchange rates in natural systems. While the structure of sediment beds obviously influences pore water flow rates and patterns, little is known about the interplay of typical sedimentary structures, hyporheic exchange, and other transport processes in fluvial/alluvial sediments. Here we discuss several processes that contribute to local-scale sediment heterogeneity and present results that illustrate the interaction of overlying flow conditions, the development of sediment structure, pore water transport, and stream-subsurface exchange. Layered structures are shown to develop at several scales within sediment beds. Surface sampling is used to analyze the development of an armor layer in a sand-and-gravel bed, while innovative synchrotron-based X-ray microtomography is used to observe patterns of grain sorting within sand bedforms. We show that layered bed structures involving coarsening of the bed surface increase interfacial solute flux but produce an effective anisotropy that favors horizontal pore water transport while limiting vertical penetration.

Original languageEnglish (US)
Pages (from-to)433-442
Number of pages10
JournalWater, Air, and Soil Pollution: Focus
Volume6
Issue number5-6
DOIs
StatePublished - Dec 1 2006

Keywords

  • Fluvial processes
  • Hyporheic exchange
  • Sediment structure
  • Sediment transport
  • Solute transport
  • Streambeds
  • Streams and rivers
  • Surface-groundwater interactions

ASJC Scopus subject areas

  • Water Science and Technology
  • Pollution
  • Earth-Surface Processes
  • Earth and Planetary Sciences(all)

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