Largescale geomorphology Classical concepts reconciled and integrated with

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

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

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

What variable is key for M 1? Is this model useful? What can we learn from it?

Steady state landscape as envisaged by Hack (1960) and Penck (1972), and adjustement to liothology as envisaged by Hack (1960)

Resistant rock band – need greater relief and steeper slopes to achieve steady state. As envisaged by Hack (1960)

Penck Framework How do the conditions of this model differ from M 1 -M 4?

Shows many characteristics of Davis’ (1899) cycle of erosion

King (1953, 1962)

“Evolves more by Davis type downwearing than by King type backwearing”

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. ”