Spatial statistics of surface roughness change derived from multi-scale digital elevation models

Surface roughness is an important variable of geomorphologic research and hydrological modeling, and widely used in the Earth and planetary science. It plays an important role in determining how a ground object will interact with its environment. Quantification of surface-roughness variability using Digital elevation model (DEM) were applied to study area of Beichuan County, one of the most destructed areas during the Wenchuan earthquake (7.9 Mw at 14:28:01.42 CST on May 12, 2008). In this paper, four types of DEM were chosen for multi-scale assessment of the surface roughness. Three algorithms were employed, which were Root mean square of elevation, standard deviation of elevation, standard deviation of curvature profile. An overall trend of inclined to be flat from pre-earthquake to post-earthquake could be examined through the three measure methods, which indicate that Wenchuan earthquake indeed had effects on changing the surface roughness. The method of Root mean square of elevation shows the most obvious results in depicting the change before and after the earthquake.