Contribution of Geosciences in the Study of Anthropogenic Activities in Different Temporal and Spatial Contexts

Abstract

From Homo sapiens, anthropogenic activities have impacted Earth systems at different spatial and time scales, particularly since the mid-twentieth century as the geological record confirms. Such impact has triggered Earth system counter reactions that threaten living species on Earth (including humans), the environment, modern infrastructure, and cultural heritage. Studying and understanding the spatial and temporal interactions between humans and Earth systems is critical in informed decision-making to prevent and mitigate the potential threats. This thesis proposes a methodological approach for studying the interaction between humans and Earth systems in three different contexts: geohazards, archaeology, and urban planning. We focus on the holistic integration of techniques used in geosciences to generate seamless models of the Earth surface and subsurface, enabling the study of the footprint of anthropogenic processes in the geologic record and in the natural landscape. These techniques have limitations, though they are complementary. In this thesis, we aim to provide technical solutions to fill knowledge gaps when integrating such techniques in the generation of holistic models. This research encompasses multidisciplinary investigations including remote sensing, geophysics, geotechnics, geology, 3D modelling, and geographic information systems (GIS). Studies were conducted in Austria, Greece, and Norway, and are summarized in four journal articles. The first article is within the geohazards context, and notably considers landslides. The study tests the performance of three well-known ground filtering algorithms when applied to laser scan data of an area with active landslides in the Austrian Alps. Most importantly, it assesses the impacts of each algorithm on the quantification of the surface deformation induced by landslides through time. Results of the study suggest that the choice of the ground filtering algorithm and its parameterization have effects when quantifying volume changes of landslides. The second and the third articles were developed under the archaeological context. The second article promotes the digital documentation of threatened archaeological sites through the combination of remote sensing and structural geology. High resolution terrestrial laser scan data was used to generate an architectural catalogue of the Late Bronze Age (LBA) Mycenaean cemetery of Aidonia, Greece. The catalogue consists of a 3D model of chamber tombs carved in the natural rock formation and tables providing 208 architectural and geological measurements. Article III builds on article II and proposes two methods for the semi-automatic identification and mapping of linear features such as chisel marks in the high-resolution laser scan data. Multidisciplinary studies of article IV were conducted in the urban context of the city of Stavanger, Norway. The article focuses on the integration of laser scan data, aerial imagery, geotechnical and ground water drilling, ground penetrating radar (GPR), and geological outcrops to generate a holistic 3D model aimed to: i) study the distribution and composition of natural and non-natural materials on the surface and near-subsurface; ii) unravel the geological history of the area since the last ice age; and iii) determine significant topographic changes that occurred in the area, particularly those induced by anthropogenic activities. This thesis proves that multidisciplinary approaches that integrate different techniques applied in geosciences are efficient for studying interconnected anthropogenic and geological phenomena at local and regional scales, and at different windows of time. The results of this research can be applied worldwide in future studies in the geohazards, archaeology, and urban planning contexts. Holistic models contribute to closing the knowledge gap between what can be seen on the surface and what cannot be seen in the subsurface.