The quantification of the socio-economic impact on geomorphology

It is acknowledged that the Earth’s surface was shaped by natural processes such as tectonic uplift, erosion and sediment movement. Nevertheless, recently, the human society as a new force to reshape the landscape has been perceived by the scientific community. The Anthropocene working group (AWG), which is a part of subcommission on Quaternary Stratigraphy – International commission on Stratigraphy of International Union of Geological Science (IUGS) proposed to mark the current geologic time unit as Anthropocene. The AWG declared human beings stepped into an epoch that our societies have become a global geophysical force and the extent of human intervention on geomorphic processes has become comparable to nature, and the trend is accelerating. Humans act as a geomorphic agent shaping Earth’s surface through activities ranging from agricultural tillage, mining, road networks and building constructions. These activities leave significant signatures on the topography, literally and figuratively across millennia and reflecting the socio-economic conditions of the societies that produce them. People tend to live in the surroundings where resources such as food and fuel are cheaper and more accessible, and the economic and social demands of resources drive the land-use changes to meet the demands. As the human population has grown and the power of technology has expanded, the socio-economic demands have scaled up, the landscapes were imprinted by the rapid increase of anthropogenic modification caused by deforestation, agricultural expansion and urban construction to supply the food and energy demands. The Great Acceleration witnessed remarkable explosion of socio-economic development, with significant consequences on the surface topography. It is estimated that humans have shaped around one-third of the landscape through agricultural fields, pastures, or urban landscapes. However, an empirical computation to link between socio-economic development, land-use changes and the geomorphology alterations is still a gap. Societal-based understanding of anthropogenic geomorphology provides the way of how human activities involved in natural environmental changes such as soil erosion, floods and tectonic uplifts with the timeline. We synthesized scientific evidence on the emergence, history of present anthropogenic features and illustrated how these features impact the Earth's surface processes. Then we integrated social-geophysical approaches to interpreting a full range of anthropogenic features with identification of remote sensing techniques and reconstruction of the long-term changes by archaeologists, as diagnostic fingerprints of the social processes that formed them. Further, we testified that the natural landscape and anthropogenic landscape present a significant difference in geomorphic signatures, and implied that anthropogenic force shapes the geomorphology in a way different from natural force. Lastly, we used the nighttime light data to represent the socioeconomic status and SLLAC (Slope Local Length of Autocorrelation) metrics to measure the anthropogenic modification on the landscape, and then to assess the correlation between socio-economic impact on the geomorphology based on each stratification of a global pattern. This thesis helps to understand how the features that human left on the topography affect the Earth surface processes, interpret those features as sociocultural fingerprints, demonstrate that the anthropogenic forcing leaves a different topographic signature on the surface from the natural forcing, and quantify the correlation between socio-economic development and anthropogenic geomorphology. This research not only fill the gap in why people shape the landscape through a diversity of activities; it also presents a possible correlation between socio-economic development and anthropogenic geomorphology. This work also provides the possibility towards an empirical estimation of landscape under the human’s impact at a global scale, and underlines that an integrated approach combining social economy, ecology and geomorphology is needed for the future landscape management.