Table 1.

Summary of geomorphic indices used in mountain front analysis, modified after Wells et al. (1988)

ParameterDefinitionDerivation*MeasurementPurposePotential difficulties
SmfSinuosity of topographic mountain frontsLmf/LsEmbedded ImageDefines the degree of topographic modification of mountain front from the position of possible controlling structures
  • Defining actual topographic junction

  • Defining discrete mountain front segments

VfValley floor width to valley height index2Vfw/[(EldEsc) – (ErdEsc)]Embedded ImageDefines the ratio of the valley floor width to the mean height of two adjacent divides, measured at given locations along a stream channel within the range block
  • Resolution of satellite imagery in defining Vfw and divide elevations

  • Effects of changes in lithology

  • Need to minimize variations in stream size (length and area)

  • *Lmf, straight line length of mountain front; Ls, sinuous length along mountain front; Vfw, valley floor width; Eld and Erd, topographic elevations of left and right valley watersheds; Esc, elevation of valley floor.

  • Schematic map view for Smf, schematic cross-section view for Vf.

  • Both indices after Bull & McFadden (1977) and Bull (1978).