Worldterrain – A Contribution to the Global Geomorphometric Atlas

H. I. Reuter1, A. D. Nelson2
1 Independent spatial consultant
Fax: (+49-3212-8912839)
Email: gisxperts@web.de
2 Independent spatial consultant
Email: dr.andy.nelson@gmail.com

A Digital Elevation Model (DEM) is one of the most useful sources of information for spatial modeling and monitoring, with applications as diverse as: Environment and Earth Science, e.g. catchment dynamics and the prediction of soil properties; Engineering, e.g. highway construction and wind turbine location optimisation; Military, e.g. land surface visualisation, and; Entertainment, e.g. landscape simulation in computer games (Hengl and Evans 2007). The extraction of land surface parameters – whether they are based on ‘bare earth’ models such as DEMs derived from contour lines and spot heights, or ‘surface cover’ models derived from remote sensing sources that include tree top canopies and buildings for example – is becoming more common and more attractive due to the increasing availability of high quality and high resolution DEM data (Gamache 2004).

Global DEM datasets are available in a different variety of resolutions. At 1km resolution the GTOPO30, GLOBE, SRTM30 and ACE2 datasets are available. However certain processes and function can only be detected at much finer scales. One of the most widely used DEM data sources is the elevation information provided by the 90m resolution Shuttle Radar Topography Mission (SRTM) (Coltelli et al. 1996, Farr and Kobrick 2000, Gamache 2004). A new 30m DEM of the world is expected to be released in June 2009 based on 1.5 Million single ASTER DEM scenes covering the whole world.

This detailed elevation data can be used to generate a geomorphometric atlas, which is particularly useful as a resource of surface measures and objects in support of decision-making and projects over a broad spectrum of applications (Gessler et al, 2007). Several attempts have been made - for example the USGS global 1 km HYDRO1k Elevation Derivative Database or the River and Catchment Database at 250 m for Europe (Vogt et al., 2003). Guth (2009) already showed some results for a SRTM based high-resolution continental geomorphometric atlas. The work performed did not contain some of the number of criteria that these dataset should inherit (Gessler et al. (2007): 1) precision, 2) multi scale, 3) open structure, 4) web access and 5) quality. However with the current datasets usually these parameters are not satisfied. Additional important points are the reuse of the generated parameters and the description in terms of metadata. This is of outmost importance as different software packages - even different versions of the same software - produce different results.

This paper describes a procedure to generate a geomorphometric atlas, which as a start will fulfill several of these criteria. The atlas is extendable to include additional parameters, whereupon suitable algorithms could be chosen to map them. The objective is to provide a standardized workflow and format, which can accommodate the expected growth in Geomorphometry applications in the future.

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