Effects of analytical window and resolution on topographic relief derived using digital elevation models

Relief has been used as an index to quantify the vertical dimension of topography in landscape evolution studies. However, potential impacts of analytical window and resolution of digital elevation models (DEMs) were seldom addressed. Here, three relief parameters (fixed-area local relief, watershed relief, and watershed mean local relief) were examined for three topographic regions (relatively flat loess-till plains in northern Missouri, hilly karst topography in southern Missouri, and a mountainous topography in western Washington) using DEMs of 30-m (USGS NED), 90-m (SRTM), and 1-km (GTOPO30), which are commonly applied in landscape evolution studies. Results indicate that both fixed-area and watershed mean local reliefs are strongly affected by the size of the analytical window, whereas watershed relief is relatively stable. The correlation between watershed relief and watershed mean local relief is affected by the edge effect in determining watershed mean local relief, especially for small watersheds. The comparisons between relief parameters derived from these three resolution DEMs indicate <5% difference between 30- and 90-m DEMs, but >15% difference between 30-m and 1-km DEMs. The relatively large disparity may affect the suitability of using the 1-km GTOPO30 DEM in relief determination.