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Spatial resolution and algorithm choice as modifiers of downslope flow computed from digital elevation models.
Introduction
The availability of digital elevation (DEM) data has been a key factor in the rise of geographic information systems as tools for environmental data management and analysis. While DEM data underlie a major proportion of GIS operations, important topographic applications of DEMs include terrain mapping and visualization, location analysis, estimation of critical slopes and landslides, forecasting flooding and its impact, optimal routing, visibility analysis, and many more. Digital elevation data are one of the most, if not the most, critical layer in what has been called the National Framework data (FGDC 2006). Within the digital representations of terrain, which Longley et al. (2005) claim can be stored in six different ways, by far the majority of data worldwide are stored in the simple grid or raster GIS data structure. The dominance of this type of data was recently further reinforced by the global release of the Shuttle Radar Topographic Mapping Mission data (Rodriguez et al. 2005). The value of DEMs for computing terrain surface structure and hydrographic features dates back some time (Douglas 1986; Wood et al. 1988; Band 1986; O'Callaghan and Mark 1984). Once algorithms were generated to compute the basic terrain parameters (Sharpnack and Akin 1969; Evans 1980; Moore et al. 1993; Quinn et al. 1991), attention focused on hydrographic feature delineation, extraction, and use in modeling (CostaCabral and Burgess 1994; Gallant and Wilson 1996; Jenson and Domingue 1988; Lea 1992; Ritter 1987; Tarboton et al. 1993; Zevenbergen and Throne 1987). More recent research has been able to comprehensively review developments in the field (Evans 1998; Wood 1996; Jenson 1991) and produce educational material based on software tools (Wilson and Gallant 2000). The role of error in the computation of surface parameters and their derivatives has been a subject of DEM research ever since the publication of some of the earliest literature in this area (Carter 1992; Chu and Tsai 1995; Hunter and Goodchild 1997; Lee 1996; Lee et al. 1992; Zhou and Liu, 2002). There has also been considerable attention paid to the quantitative differences among results computed by different algorithms (Jones 1988; Ryder and Voyadgis 1996; Wolock and M...See the full content of this document
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