Geomorphometry

Geomorphometry, or geomorphometrics, is the science of quantitative land surface analysis.[1] It gathers various mathematical, statistical and image processing techniques that can be used to quantify morphological, hydrological, ecological and other aspects of a land surface. Common synonyms for geomorphometry are geomorphological analysis, terrain morphometry or terrain analysis and land surface analysis. Geomorphometrics is the discipline based on the computational measures of the geometry, topography and shape of the Earth's horizons, and their temporal change.[2]

In simple terms, geomorphometry aims at extracting (land) surface parameters (morphometric, hydrological, climatic etc.) and objects (watersheds, stream networks, landforms etc.) using input digital land surface model (also known as digital elevation model, DEM) and parameterization software.[3] Extracted surface parameters and objects can then be used, for example, to improve mapping and modelling of soils, vegetation, land use, geomorphological and geological features and similar.

With the rapid increase of sources of DEMs today (and especially due to the Shuttle Radar Topography Mission and LIDAR-based projects), extraction of land surface parameters is becoming more and more attractive to numerous fields ranging from precision agriculture, soil-landscape modelling, climatic and hydrological applications to urban planning, education and space research. The topography of almost all Earth has been today sampled or scanned, so that DEMs are available at resolutions of 100 m or better at global scale. Land surface parameters are today successfully used for both stochastic and process-based modelling, the only remaining issue being the level of detail and vertical accuracy of the DEM.

History

Although geomorphometry started with ideas of Brisson (1808) and Gauss (1827), the field did not evolve much until the construction of the first DEM.[4]

Geomorphology has a long history as a concept and area of study, with geomorphometry being one of the oldest related disciplines.[5] Geomatics is a more recently evolved sub-discipline, and even more recent is the concept of geomorphometrics. This has only recently been developed since the availability of more flexible and capable geographic information system (GIS) packages, as well as higher resolution Digital Elevation Model (DEM).[6] It is a response to the development of this GIS technology to gather and process DEM data (e.g. remote sensing, the Landsat program and photogrammetry).

Techniques

With a topographic landscape the question arises as to where a feature is and also as to how accurately it can be classified or identified. Geomorphometrics involves deriving values from the DEM data that infer geomorphological features, such as whether relative local values describe peaks, passes, pits, planes, channels and ridges. Due to limitations of resolution, axis-orientation, and object-definitions the derived spatial data may yield meaning with subjective observation or parameterisation, or alternatively processed as fuzzy data to handle the varying contributing errors more quantitatively – for example as a 70% overall chance of a point representing the peak of a mountain given the available data, rather than an educated guess to deal with the uncertainty.[7]

Applications

Quantitative surface analysis through geomorphometrics provides the tools for scientists and managers interested in land management.[8] Applications areas include:

Geomorphometricians

As a relatively new and unknown branch of GIS the topic of geomorphometrics has few ‘famous’ pioneer figures as is the case with other fields such as hydrology (Robert Horton) or geomorphology (G. K. Gilbert[9]). In the past geomorphometrics have been used in a wide range of studies (including some high-profile geomorphology papers by academics such as Evans, Leopold and Wolman) but it is only recently that GIS practitioners have begun to integrate it within their work.[10][11] Nonetheless it is becoming increasingly used by researchers such as Andy Turner and Joseph Wood.

International organisations

Large institutions are increasingly developing GIS-based geomorphometric applications, one example being the creation of a Java-based software package for geomorphometrics in association with the University of Leeds.

Training

Academic institutions are increasingly devoting more resources into geomorphometrics training and specific courses although these are still currently limited to a few universities and training centres. The most accessible at present include online geomorphometrics resource library in conjunction with the University of Leeds and lectures and practicals delivered as part of wider GIS modules, the most comprehensive at present offered at the University of British Columbia (overseen by Brian Klinkenberg) and at Dalhousie University.

Geomorphometry/geomorphometrics software

The following computer software has specialized terrain analysis modules or extensions (listed in alphabetical order):

Disciplines Geomorphometrics covers

See also

References

  1. ↑ Pike, R.J.; Evans, I.S.; Hengl, T. (2009). "Geomorphometry: A Brief Guide" (PDF). http://geomorphometry.org/. Developments in Soil Science, Volume 33 © 2009 Elsevier B.V. Retrieved 02-09-2014. Check date values in: |access-date= (help); External link in |website= (help)
  2. ↑ Turner, A. (2006) Geomorphometrics: ideas for generation and use. CCG Working Paper, Version 0.3.1 [online] Centre for Computational Geography, University of Leeds, UK; Accessed 7 May 2007
  3. ↑ Evans, Ian S. (15 January 2012). "Geomorphometry and landform mapping: What is a landform?". Geomorphology. Elsevier. 137 (1): 94–106. doi:10.1016/j.geomorph.2010.09.029. Retrieved 2 September 2014.
  4. ↑ Miller, C.L. and Laflamme, R.A. (1958): The Digital Terrain Model-Theory & Application. MIT Photogrammetry Laboratory
  5. ↑ Schmidt, J. & Andrew, R. (2005) Multi-scale landform characterization. Area, 37.3; pp341–350.
  6. ↑ Turner, A. (2007) Lecture 7: Terrain analysis 3; geomatics, geomorphometrics [online] School of Geography, University of Leeds, UK; Accessed 7 May 2007
  7. ↑ Fisher, P, Wood, J. & Cheng, T. (2004) Where is Helvellyn? Fuzziness of multi-scale landscape morphometry. Transactions of the Institute of British Geographers, 29; pp106–128
  8. ↑ Albani, M., Klinkenberg, B. Anderson, D. W. & Kimmins, J. P. (2004) The choice of window size in approximating topographic surfaces from Digital Elevation Models. International Journal of Geographical Information Science, 18 (6); pp577–593
  9. ↑ Bierman, Paul R., and David R. Montgomery. Key concepts in geomorphology. Macmillan Higher Education, 2014.
  10. ↑ Chorley,R.J. 1972. Spatial Analysis in Geomorphology. Methuen and Co Ltd, UK
  11. ↑ Klimanek,M. 2006. Optimisation of digital terrain model for its application in forestry, Journal of Forest Science, 52 (5); pp 233–241.

Further reading

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