An assessment of geomorphic change and its effects on denudation and landscape evolution

An analysis and assessment of the effects of human activity on geomorphic processes related to denudation/sedimentation and landscape change, is presented. The analysis focuses on changes occurred during the last couple of centuries and is based on a variety of case studies from different regions as well as global assessments. Data compiled show that certain geomorphic processes are experiencing an important acceleration, in particular since the 1950’s. The acceleration seems to have a global character and suggests a “global geomorphic change” is taking place, largely due to anthropogenic landscape changes.

            Denudation directly caused through activities involving excavation, transport and accumulation of geological materials has increased by a factor of 30 between 1950 and 2015. Direct plus indirectly human-induced denudation (triggered by land surface alteration) is presently at least one order of magnitude greater than denudation due to purely natural processes. A general increase of sedimentation rates seems to have taken place since the end of the 19^th century, and more intensely after the mid-20^th century. This appears to respond mainly to land surface changes, in conjunction with climate change.

            Slope movements, which represent an important contribution to denudation, sediment generation and landscape evolution, show a clear intensification, in particular after mid-twentieth century. Frequency of disasters related to such movements (an indirect measure of process frequency) in specific regions, as well as continent and global levels, has grown considerably and the general increasing trend observed is not satisfactorily explained by climate change. It rather appears to reflect increasing landscape (land use and land cover) changes. A similar increase in the frequency of flood-related disasters has been recorded.

            The results obtained suggest that the extensive landscape changes described, related to the intensification of human activities affecting land surface, represent a geomorphic change of a global extent. This change shows an acceleration coinciding with the “great acceleration” proposed as one of the manifestations of the Anthropocene.