Statistical Characterization of Altitude Matrices by Computer. Report 4. Frequency Distributions of Gradient.
Abstract
Gradient is the most important attribute of surface geometry and its frequency distribution is considered here in detail to assess how it may be summarised, for example by fitting various models. Plots on probability paper are made of gradients from altitude matrices of 25 to 100m mesh, for five square areas and for two drainage basins, from meshes of variable triangles averaging 33 to 244m in linear dimension, for five drainage basins, from relief per 1 x 1 km square for large morphological regions, and from field measurements over distances of 1.5 to 10m along profiles, the location of which was subjective. Although some support is provided for Speight's suggestion that taking the logarithm of tangent normalises frequency distributions, in some cases better results are obtained from the square root of sine, or even from no transformation of slope angle in degrees. The main transformations have similar effects over a broad range of gradients, and most existing data sets are insensitive to the difference between them. But the differences which are found here are probably due to differences in terrain, more than the use of different measuring techniques or differently-defined study areas.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1977
- Accession Number
- ADA096651
Entities
People
- H. Lemons
- Ian S. Evans
Organizations
- Durham University