Fractals in topography: Application to geoarchaeological studies in the surroundings of the necropolis of Dahshur, Egypt

摘要

The necropolis of Dahshur in northern Egypt witnessed human-environment interaction on a millennial scale but to an unknown extent. The present study aims to decipher ephemeral channel networks, which are common landscape features in the surroundings of the necropolis, from landforms that were subject to human influence. The analysis was carried out on the basis of surface geometry as derived from a digital elevation model (DEM). The hypothesis is tested that the natural fractal patterns of channel networks lead to fractal surface topography, when fluvial processes are the main factors for relief evolution. Therefore, the estimated fractal dimension of channel networks is correlated with the fractal dimension of surface topography to determine the mutual functional relationship. A high degree of functional relationship within some areas of the DEM shows that channel networks are self-similar branching trees that imprint their geometry on to surface topography in a scale range of ~15 to ~ 190 m. A low correlation of fractal patterns of channel network and surface topography in the vicinity of the pyramid district of the necropolis is interpreted as channel beds modified or induced by human impact, either due to the usage of the channel beds as transport ways for building material leading to an acceleration of processes like soil erosion or due to direct activities like mining or landscape architecture.