Modelling erosional sensitivities of archaeological sites using DEM’s from low altitude UAV imagery

In South Africa, archaeological sites that are open and exposed are often subject to degradation via erosion, allowing the archaeological material throughout these landscapes to be displaced resulting in a loss of archaeological context over time. As erosional sensitivities become higher, the condition of these sites continue to degrade, and artefacts and artefact deposits can be eroded from their in-situ positions and integrated into the landscape. This in turn reduces the integrity of the archaeological deposits at a site resulting in a loss of information. Providing an erosional risk-based assessment using the Revised Universal Soil Loss Equation (RUSLE) demonstrating the destructive processes operating at a site and the material most at risk, can allow for the integrity of archaeological clusters and material to be assessed. Providing easily interpretable outputs using GIS based analyses that clearly demonstrate the destructive processes operating at a site based on a method that is adaptable, can allow for research in the area to be tailored to regions of higher and lower importance, whilst providing information about past and potential artifact migration patterns in the landscape. This project aims to generate Digital Elevation Models (DEMs) and maps that illustrate and quantify this potential erosion and possible loss of integrity across two open-air sites along the Doring River in the Western Cape of South Africa. By combining Unmanned Aerial Vehicle (UAV) acquired imagery with GNSS RTK collected survey data, accurate representations and DEMs of each site could be produced and a baseline for assessing the integrity of the existing archaeological material and deposits could be created. From this, erosion risk was mapped and an urgency matrix developed to identify material most at risk across a site, as well as which archaeological deposits are most susceptible to erosion. This provides insight into areas that are most prone to erosion and are therefore most vulnerable to loss of information and context, which is particularly important in the current setting. The results of the project can not only illustrate destructive processes acting at each of the sites, but also provide information about formation processes and geomorphology of each of the archaeological sites and Doring River region.