Large-scale geomorphology: Classical concepts reconciled and integrated with contemporary ideas via a surface process model

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Large-scale geomorphology Classical concepts
reconciled and integrated with contemporary ideas
via a surface process model
Kooi and Beaumont 1996
Photo credit John S. Shelton
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3 Scales

• Micro
• Uniform gradient
• No channels or hillslopes represented
• Meso
• Groups of microscale subsystems
• Individual interfluves
• Macro
• Groups of mesoscale subsystems
• Model landscape which consists of many drainage
  basins
• When this is in steady state, so are the smaller
  subsystems

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Model Formulation Equations
Short range transport modeled as linear diffusion
(hillslope)
Diffusivity
Long range transport (fluvial)
Local discharge
Downstream slope
Transport coefficient
Precipitation
Sediment flux
Erosion length scale
Local undercapacity of the river
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What variable is key for M1? Is this model
useful? What can we learn from it?
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Steady state landscape as envisaged by Hack
(1960) and Penck (1972), and adjustement to
liothology as envisaged by Hack (1960)
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Resistant rock band need greater relief and
steeper slopes to achieve steady state. As
envisaged by Hack (1960)
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Penck Framework
How do the conditions of this model differ from
M1-M4?
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Shows many characteristics of Davis (1899) cycle
of erosion
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King (1953, 1962)
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Evolves more by Davis type downwearing than by
King type backwearing
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Summation

• Role of baselevels, grade, steady state
  equilibrium landforms
• Davis type (downwearing peneplanation)
• Penck type (waxing and waning development)
• King type (escarpment retreat, pediplanation)
• Hack type (dynamic equilibrium, response times,
  geometrical complex response)
• The key factors that control the integration of
  these concepts in the model framework are the
  nature of the tectonic uplift geometry and its
  timescales.