IAP-26-091

Monitoring environmental impacts on archaeology using geophysical methods

Shallow groundwater dynamics regulate redox conditions and biogeochemical processes in the near-surface environment. It is readily established that the frequency and magnitude of extreme rainfall and drought is increasing with a warming climate; these patterns, in turn, alter the subsurface conditions. The preservation of archaeological deposits depends on stable burial conditions, and under changing subsurface conditions, these environments may become unstable. This instability leads to irreversible damage of culturally significant historic artefacts.

Current monitoring approaches rely on invasive and spatially sparse point measurements of the near-surface that assume subsurface processes are homogeneous and that all parts of the surrounding landscape respond in the same way. Additionally, deploying point methods at an entire site or landscape scale to assess the environmental risk on organic deposits is both expensive and invasive. Geophysical methods offer a non-invasive alternative for monitoring the near-subsurface at scale as they can measure a wide range of subsurface properties, including induced polarisation, magnetic susceptibility, resistivity, and dielectric permittivity.

The purpose of the project is to explore the potential of applying geophysical methods to monitor environmental conditions in an archaeological setting. This project will develop a 4D (time-lapse and 3D) inversion framework for Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Electromagnetic Induction (EMI), Induced Polarisation (IP) data that tracks subsurface changes over seasonal periods and drought/storm driven wetting and drying. The core contribution of using these methods in tandem is a time-lapse surveying framework, to monitor changes in the subsurface environment across multiple seasons. The UNESCO Roman forts of Vindolanda and Magna provide an exceptional natural laboratory to develop such a framework, since their subsurface properties are known, point measurement methods are established, and both sites contain excavated archaeological deposits with known dimensions. By testing in multiple locations, this project also tests the transferability of the framework to assess other historic and archaeological sites’ risk to future environmental change. The outputs will be validated against the Vindolanda and Magna’s point sensors. The candidate will conduct fieldwork at both sites across the seasons, supported by the Vindolanda Trust archaeological team. As a result, the output of this project directly supports the heritage economy by identifying where and when archaeological deposits are at risk from changing environmental conditions, in a way that current point monitoring methods cannot.

Year 1

– Conduct bibliographic research into near-surface biogeochemical processes, geophysical methods, and the archaeology of the Roman frontier.
– Meet with stakeholders to understand the environmental and heritage concerns of Vindolanda and Magna.
– Initial familiarisation and exploration of geophysical fieldwork, learning how ERT, GPR, EM, and IP equipment work.
– Conduct pilot fieldwork to inform the design of future data collection surveys.
– Compilation and exploration of initial field data.

Year 2

– Work closely with archaeologists and heritage managers at Vindolanda and Magna to collect field data across all seasons.
– Placement with CASE partner – the student will be given the chance to engage with active conservation initiatives which further informs the importance of environmental risk in this industry.
– Attend national and international conferences (e.g., Festival Council for British Archaeology, Lake District National Park Archaeology Conference, EGU General Assembly) and present initial findings of the framework from the pilot fieldwork.

Year 3

– Conduct advanced geophysical inversion of the collected data to determine how the groundwater conditions have changed over the course of all conducted fieldwork.
– Share the results of the inversion with the CASE partner and discuss how the results fit into the trusts’ environmental monitoring and conservation efforts.
– Design a series of outreach and museum resources for wider public engagement and understanding of environmental risk to archaeology using the results.

Year 3.5

– Preparation of thesis.
– Develop and publish further resources (videos, images, posters, exhibits etc.) to showcase the results of the framework in relevant heritage sites.
– Discussions with stakeholders to design conservation initiatives.

The student will develop advanced skills in environmental fieldwork, computational geophysics, and science communication to both specialist and non-specialist audiences, working between Durham’s geophysics group and the Vindolanda Trust’s archaeological team to build this specialist techno-environmental framework.

For the fieldwork element of the PhD, the student will be trained to use advanced geophysical surveying equipment (ERT, GPR, EM, and IP), and be guided on the industry standard for working with landowners, regulatory bodies, and heritage organisations.

The computational element of the PhD will see the student receive training in Python programming for forward modelling and geophysical inversion. Specifically, this includes the use of advanced geophysical inversion and tomographic imaging software (e.g. PyGimli, https://www.pygimli.org/, ParaView, ArcGIS) and statistical packages (e.g. SciPy, Matplotlib) to visualise and analyse the collected field data.

The student will also have plenty of opportunities to develop their scientific communication skills with a range of stakeholders; this includes publishing scientific papers and creating resources for wider public engagement relating to the theory behind the developed framework and the importance of monitoring archaeological sites.