Geomorphometry: A Brief Guide

Geomorphometry is the science of quantitative land-surface analysis (Pike, 1995, 2000a; Rasemann et al., 2004). It is a modern, analytical-cartographic approach to representing bare-earth topography by the computer manipulation of terrain height (Tobler, 1976, 2000). Geomorphometry is an interdisciplinary field that has evolved from mathematics, the Earth sciences, and — most recently — computer science (Figure 1). Although geomorphometry1 has been regarded as an activity within more established fields, ranging from geography and geomorphology to soil science and military engineering, it is no longer just a collection of numerical techniques but a discipline in its own right (Pike, 1995). It is well to keep in mind the two overarching modes of geomorphometric analysis first distinguished by Evans (1972): specific, addressing discrete surface features (i.e. landforms), and general, treating the continuous land surface. The morphometry of landforms per se, by or without the use of digital data, is more correctly considered part of quantitative geomorphology (Thorn, 1988; Scheidegger, 1991; Leopold et al., 1995; Rhoads and Thorn, 1996). Geomorphometry in this book is primarily the computer characterisation and analysis of continuous topography. A fine-scale counterpart of geomorphometry in manufacturing is industrial surface metrology (Thomas, 1999; Pike, 2000b). The ground beneath our feet is universally understood to be the interface between soil or bare rock and the atmosphere. Just what to call this surface and its science of measurement, however, is less obvious. Numerical representation of the