Enhancement of seepage and lateral preferential flow by biopore distributions in hillslopes

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Enhancement of seepage and lateral preferential
flow by biopore distributions in hillslopes

• John L. Nieber
• Department of Biosystems Engineering
• University of Minnesota

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(Copied from M. Kirkby, Hillslope Hydrology)
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Outline

• Introduction
• Observations of lateral biopores in sloping soils
• Evidence of enhanced flow and transport by
  biopores
• Modeling of flow and transport through biopore
  networks in hillslopes
• Conclusions

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Introduction

• Through normal biological functions soil fauna
  and flora develop networks of channels.
• These channels have orientations in all
  directions and
• Vertically oriented channels have long been
  recognized to provide rapid flow and transport
  vertically into the soil profile.
• More studies now show that the network of
  channels also facilitate rapid movement along
  hillslope segments.
• Impact on runoff generation and contaminant
  transport is hypothesized to be significant
  compared to flow and transport in the soil matrix.

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Observations of Biopores in Sloping Soils
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Hitachi Ohta basin in Japan (copied
from Tsuboyama et al., 1994)
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Setup at soil pits (copied from Tsuboyama et al.,
1994)
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Hydrographs and chloride breakthrough at various
points on pit face (copied from Tsuboyama et al.,
1994)
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Summary of flow and chloride breakthrough at
various points on pit face for two runs (copied
from Tsuboyama et al., 1994)
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Method for locating active macropores (copied
from Noguchi et al., 1999)
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Sample observations of macropores (copied from
Noguchi et al., 1999)
Note The C horizon is metamorphic rock schist
and amphibolite.
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Quantified the following for macropores

• Size x-section area
• Eccentricity
• Tortuosity
• Length
• Orientation
• Evenness of distribution

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Conclusions about morphology and formation
processes(from Noguchi et al. 1999)

• Mean diameter 1.5 cm
• Mean density 43/m2
• Mean length 11.6 cm
• Majority initially formed by roots and are
  generally circular in x-section. Elliptical shape
  comes about due to compression during root decay.
  Water flow in the formed pores then causes
  erosion, further enhancing the size.
• Based on comparison to other sites, the
  persistence of high water table helps to increase
  and maintain macropoes and soil pipes.

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Soil pipes in the landscape
Map of the experimental site in the Maesnant
Basin showing soil pipes (Copied from Jones and
Connelly, 2002)
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Copied from Putty and Prasad, 2000)
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Significance of Biopores in Sloping Soils on
Runoff Generation
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Experiment of Buttle and McDonald (2002)
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Experiment of Buttle and McDonald (2002) Ae
organic horizon INT middle layers include
macropore flow BR - bedrock
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Experiment of Buttle and McDonald (2002) Ae
organic horizon INT middle layers include
macropore flow BR - bedrock
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Copied from Sidle et al. (2000)
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Copied from Putty and Prasad, 2000
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Relative contributions of pipeflow. Copied from
Jones (1997)
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Concepts of Preferential flow in Sloping Soils(I
have identified three distinct concepts)

• Rapid flow through vertical macropores to
  substrate interface and buildup of perched
  saturated zone. Lateral movement over the
  interface through the soil matrix and small
  disconnections at the interface.
• Rapid flow through vertical macropores to
  substrate interface and buildup of perched
  saturated zone. Lateral movement through network
  of macropores that might not be directly
  connected. Also, connection of lateral macropores
  with runoff generated at the surface or horizon
  interface.
• Rapid flow through vertical macropores to
  substrate interface and buildup of perched
  saturated zone. Lateral movement through soil
  pipes (large continuous macropores).

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Concept 1. Copied from Buttle and McDonald (2002)
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The degree of connection of the macropore network
increases as the wetness of the soil increases.
When the soil is dry, flow will be in the
matrix, while as it wets up flow will transfer to
the macropores. (figure copied from Tsuboyama
et al. 2003)
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Illustration of increasing connectivity of flow
paths (copied from Sidle et al., 2000)
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Map of the experimental site in the Maesnant
Basin showing soil pipes (Copied from Jones and
Connelly, 2002)
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Concept of entry of water into pipes. (Copied
from Jones and Connelly, 2002)
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Sample pipe x-section shapes (Copied from Jones
and Connelly, 2002)
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Modeling of flow and transport through biopore
networks in hillslopes

• Model by Beckers and Alila (2004)
• Models for soil pipe hydrology by Jones and
  Connelly (2002) Barcelo and Nieber (1982)

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Carnation Creek study area (copied from Beckers
and Alila, 2004)
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Simulated and recorded flows (copied from Beckers
and Alila, 2004)
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Ranking of importance of flow components
matrix, slow preferential and fast preferential
(copied from Beckers and Alila, 2004)
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Map of the experimental site in the Maesnant
Basin showing soil pipes (Copied from Jones and
Connelly, 2002)
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Conceptual model of the experimental site in the
Maesnant Basin (Copied from Jones and Connelly,
2002)
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Simulation of measured pipeflow (Copied from
Jones and Connelly, 2002)
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Hillslope configuration converging slope
curvature with a pipe network
Soil matrix and macropore contributions to
hillslope runoff generation
(Copied from Barcelo and Nieber, 1982)
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Research Issues

• What determines the dominant type of preferential
  flow at a given location? Soil, topography,
  vegetation, climate, local fauna?
• What is the threshold that leads to the change
  from matrix flow to preferential flow?
• Do soil pipes evolve from soil macropores such as
  root channels and faunal tunnels? If so, under
  what conditions do they form?
• Etc...

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References

• Barcelo, M.D. and J.L. Nieber, 1982. Influence of
  soil pipe networks on catchment hydrology, Paper
  No. 82-2026, Presented at the 1982 summer meeting
  of the ASAE, Madison, WI.
• Beckers, J. and Y. Alila, 2004. A model of rapid
  preferential hillslope runoff contributions to
  peak flow generation in a temperate rain forest
  watershed, Water Resour. Res., 40
  doi10.1029/2003WR002582.
• Buttle, J.M. and D.J. McDonald, 2002. Coupled
  vertical and lateral preferential flow on a
  forested slope, Water Resour. Res., 38
  10.1029/2001WR000773
• Holden, J., 2005. Piping and woody plants in
  peatlands Cause or effect?, Water Resour. Res.,
  41doi10.1029/2004WR003909
• Jones, J.A.A., 1997. Pipeflow contributing areas
  and runoff response, Hydrol. Proc., 1135-41.
• Jones, J.A.A. and L.J. Connelly, 2002. A
  semi-distributed simulation model for natural
  pipeflow, J. Hydrol., 26228-49.
• Kung, K.-J. S., M. Hanke, C. S. Helling, E. J.
  Kladivko, T. J. Gish, T. S. Steenhuis, and D. B.
  Jaynes , 2005. Quantifying Pore-Size Spectrum of
  Macropore-Type Preferential Pathways, Soil Sci.
  Soc. Am. J., 691196-1208.
• Noguchi, S., Y.Tsuboyama, R.C. Sidle, and I.
  Hosoda, 1999. Morphological characteristics of
  macropores and the distribution of preferential
  flow pathways in a forested slope segment, Soil
  Sci. Soc. Am.J., 631413-1423.
• Putty, M.R.Y. and R. Prasad, 2000. Runoff
  processes in headwater catchments An
  experimental study in western Ghats, South India,
  J. Hydrol., 23563-71.
• Sidle, R.C., S. Noguchi, Y. Tsuboyama and K.
  Laursen, 2001. A conceptual model of preferential
  flow systems in forested hillslopes evidence of
  self-organization, Hydrol. Process.,
  151675-1692.
• Sidle, .C., Y. Tsuboyama, S. Noguchi, I. Hosoda,
  M. Fujieda and T. Shimizu, 2000. Stormflow
  generation in steep forested headwaters a linked
  hydrogeomorphic paradigm, Hydrol. Process.,
  14369-385.
• Tsuboyama, Y., R.C. Sidle, S. Noguchi, and I.
  Hosoda, 1994. Flow and transport through the soil
  matrix and macropores of a hillslope segment,
  Water Resour. Res., 30879-890.

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Other Information(Some text and other references)
See the handout document for more details on this
subject Lateral preferential flow on
hillslopes through pathways formed by biological
and mechanical processes by John L. Nieber,
extended Abstract for the Biohydrology Conference
to be held in Prague, Sept. 21-22, 2006.
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Observations at Town Brook
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Observations at Town Brook
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