Erosion of noncohesive sediment by groundwater seepage: Lysimeter experiments and modeling

Garey A. Fox, Maria Chu-Agor, Glenn Wilson

Research output: Contribution to conferencePaper

Abstract

Seepage may be a significant mechanism of streambank erosion and failure in numerous geographical locations. Previous research has investigated erosion by lateral subsurface flow and developed a sediment transport model similar to an excess shear stress equation. As a continuation of this earlier research, slope destabilization driven by lateral, subsurface flow was studied to further verify the recently proposed sediment transport model. Laboratory experiments were performed using a two-dimensional soil lysimeter. The experiments were conducted on two sandy soils: a field soil (loamy sand) and a sieved sand with greater sand content and less cohesion. A series of seven lysimeter experiments were performed for the two different sands by varying the bank slope (90°, 60°, 45°, 36°, and 26°). Flow and sediment concentrations were measured at the outflow flume. Pencil-size tensiometers were used to measure soil pore-water pressure. Results indicate that a slight modification of the existing seepage sediment transport model adequately simulates lysimeter experiments for both noncohesive soils without modifying the seepage parameters of the excess shear stress equation, especially for bank angles greater than 45°. The research then determined whether integrated finite element and bank stability models were capable of capturing both small and large scale sapping failures. The models predicted large-scale failures for bank angles greater than 45° in which tension cracks formed on the bank surface. The models failed to predict collapses for bank angles less than 45° in which tension cracks formed on the seepage face. The failure to predict collapse was hypothesized to be due to the assumption of circular arc slip surfaces.

Original languageEnglish (US)
StatePublished - Nov 7 2007
Externally publishedYes
Event2007 ASABE Annual International Meeting, Technical Papers - Minneapolis, MN, United States
Duration: Jun 17 2007Jun 20 2007

Other

Other2007 ASABE Annual International Meeting, Technical Papers
CountryUnited States
CityMinneapolis, MN
Period6/17/076/20/07

Keywords

  • Bank stability
  • Groundwater
  • Seepage
  • Streambank erosion
  • Streambank failure

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Engineering(all)

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    Fox, G. A., Chu-Agor, M., & Wilson, G. (2007). Erosion of noncohesive sediment by groundwater seepage: Lysimeter experiments and modeling. Paper presented at 2007 ASABE Annual International Meeting, Technical Papers, Minneapolis, MN, United States.