Defining Mountain Regions

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Mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill.
Mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill.

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[edit] Defining Mountain Regions

Geographers have produced numerous definitions aiming to distinguish mountain environments from non-mountains; many build on common perceptions of what constitutes a mountain, and none is fully quantitative.

With the support of the Swiss Development Corporation, UNEP-WCMC used criteria based on altitude and slope in combination in order to represent the environmental gradients that are key components of mountain environments (Kapos et al. 2000).

Topographical data from the GTOPO30 global digital elevation model (USGS EROS Data Centre 1996) were used to generate slope and local elevation range on a 30 arc-second grid of the world. These parameters were combined with elevation to arrive at the empirically derived definitions of six mountain classes.

To reduce projection distortion in the original dataset, analysis was based on continental subsets in equidistant conic projection.


[edit] Class of Mountains

  • 1 elevation > 4 500 m
  • 2 elevation 3 500 – 4 500 m
  • 3 elevation 2 500 – 3 500 m
  • 4 elevation 1 500 – 2 500 m and slope ‡ 2°
  • 5 elevation 1 000 – 1 500 m and slope ‡ 5° or local elevation range (7 km radius) > 300 m
  • 6 elevation 300 – 1 000 m and local elevation range (7 km radius) > 300 m
  • 7 isolated inner basins and plateaus less than 25 km2 in extent that are surrounded by mountains but do not themselves meet criteria 1-6

The seventh class was introduced in the 2002 revision of the original 2000 system. The global mountain area thus defined is almost 40 million km2, or some 27 per cent of the Earth's surface. If all Class 7 areas are excluded, the total area classified as mountainous falls to 39.3 million km2, and the area of nonmountain land increases to 107.6 million km2.

Antarctica has been excluded from the statistics presented in this report; this reduces the proportion of land area classified as mountainous to around 24 per cent. Future work will try to incorporate bioclimatic data into this formal topographic definition in order to model regional and latitudinal variations in the transition to mountain conditions.

Another study (Meybeck et al., 2001) used the same digital elevation model and a combination of ‘relief roughness’ and elevation to partition the entire land surface into 15 classes of relief typology. In this system, Tibet and the Altiplano are classed as ‘very high plateau’ rather than mountains, and the global mountain area is calculated as 33.5 million km2.


[edit] Also see

[edit] Reference

  1. Wikipedia see Mountain [1]
  2. Mountain Watch Defining Mountain Regions [2]

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