Research over the past decade has demonstrated the feasibility of extracting topographic information of hydrological interest directly from digital elevation models (DEM). Techniques are available for extracting slope properties, catchment areas, drainage divides, channel networks and other data (Jenson and Domingue, 1988; Mark, 1988; Moore et al., 1991; Martz and Garbrecht, 1992). These techniques are faster and provide more precise and reproducible measurements than traditional manual techniques applied to topographic maps (Tribe, 1991)
