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MEGALITH: An Investigation Into The Conservation of Our Megaliths

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MEGALITH is a research project focusing on the Mnajdra Temples, a complex of three temples which are among the oldest free-standing structures in the world. The project aims to understand and simulate stone degradation under various environmental conditions to plan better conservation practices, including preventive ones. THINK speaks with lead researcher Prof. Ing. Daniel Micallef and project partners Prof. JoAnn Cassar and Dr Joel Azzopardi about why this project was needed, its methodology and its potential outcomes.

The Maltese Islands are home to some of the world’s oldest prehistoric temples. Unfortunately, continuous exposure to the elements causes these Temples to suffer from ongoing stone degradation. The MEGALITH project builds on recent efforts to understand, and hopefully help mitigate, these environmental impacts by generating simulations that allow the team to combine meteorological effects and resulting stone degradation on these sites. Mnajdra, a UNESCO World Heritage site, was chosen as a case study for this project.

The project received funding in November 2023, building on conservation-focused studies that have been conducted over many years by the same group, and others, in collaboration with Heritage Malta and Italian colleagues. ‘Currently, the Temples are covered with a shelter that protects from rain, provides shading, and reduces temperature fluctuations between day and night. However, the researchers understand that the sites are also exposed to other environmental elements, particularly wind, which can cause erosion and instigate salt damage,’ explains Prof. Ing. Daniel Micallef from the Department of Environmental Design.

While we are usually able to forecast large-scale weather conditions from weather stations, the goal of this research is to simulate what occurs inside the Temples under different wind conditions. This is particularly valuable as the proximity of Mnajdra to the cliff means that the wind generally carries sea salt from the sea, triggering and exacerbating existing problems. ‘We are going to feed an Artificial Intelligence (AI) model with simulation and climatic data from satellite and ground data to observe local conditions around and inside the Temples,’ elaborates Micallef.

Figure 1: Wind flow around the Temples provides invaluable information not only on erosion processes but also on salt transport from the sea, localised humidity, and temperature fluctuations on individual stones, which are variables that affect the stone’s degradation.

The Project’s Methodology

MEGALITH employs Computational Fluid Dynamics (CFD) alongside an AI model to simulate and understand degradation across a spectrum of environmental scenarios, basing this on other on-site studies of the megaliths. CFD uses physics equations that describe the behaviour of air. By solving these equations using computers, CFD allows the team to study and understand how air moves and behaves in various scenarios.

The goal is to create a dataset and develop an AI model based on it. The simulations will include low, moderate, and high wind speeds, and the simulation results will be coupled with AI so that the model can predict the scenarios over an entire year.

Prof. Ing. Daniel Micallef

Simulating all the possible different wind conditions would require a long time, which is why the team is also using AI to extrapolate the contained simulation results obtained over a whole year. The AI model needs to be fed with what is called ‘training data’ from a large number of simulations.

Two validation methods are being employed to ensure the reliability of the simulation. First, the simulations are compared with wind measurements taken on-site by Heritage Malta before shelter construction. Second, once the AI model is ready, the team will compare degradation patterns from previous years, obtained through photos and condition surveys, with simulated ones to validate their accuracy on-site.

When asked about some of the challenges the team faces, Micallef explained that the simulation techniques they are using are very demanding and require a lot of computational power. Moreover, the number of simulations needed to train the AI model is quite large and must be completed in just a few months, as the project spans only a year and a half. However, they are utilising computing clusters at UM to run many simulations simultaneously, and are working closely with a number of Research Support Officers working on this and related projects.

Future Decisions on Preservation

Current solutions, such as the protection offered by the shelters, help conserve the Temples. However, the team is convinced that further modifications can be proposed on the basis of this and similar studies, such as closing off certain areas of the shelter with ‘flaps’ so that the effects of certain wind directions, especially those coming from the direction of the sea, are reduced.

This study not only has the potential to aid in conserving the Mnajdra Temples, which serves as a representative site, but its findings could also extend to help in the preservation of various structures. The methodology, once verified, could enable degradation predictions of similar materials in a similar environment through simulations, making it applicable to different types of buildings to assess their vulnerability to wind and climate impacts.

Studies like MEGALITH are still lacking. So far, conservation professionals have focused on direct stone analysis combined with existing environmental data but have yet to employ simulation methodologies. ‘In reality, stone conservation requires a multidisciplinary approach involving engineers, conservators, scientists, and others,’ emphasises Micallef. This is the approach taken by UM and Heritage Malta in their collaboration.

MEGALITH’s Next Steps

The team has already gathered extensive climatic data on weather conditions around Malta. They are currently focusing on detailed wind measurements on-site, including terrain and sea factors, and more closely on the Temples themselves. Later, they will pinpoint areas with severe, documented degradation. By summer, they plan to begin comprehensive simulations and validate the AI model. 

The MEGALITH project is progressing swiftly, transitioning from large-scale simulations to detailed models of the temple complex for precise AI-simulated predictions. ‘The transition will move from gathering weather condition reports spanning across the entire Islands to focusing on a specific area within the Temples, down to a few centimetres,’ explains Micallef, ensuring utmost accuracy.

Figure 2: Digital representation of one of the apses of the Mnajdra Temples. This detailed geometric data with sub-centimetre resolution enables accurate flow simulations to be carried out. Source: Data provided by Heritage Malta.

This project aims to significantly enhance preservation strategies and potentially benefit heritage conservation efforts more broadly. Heritage Malta is a key supporter of MEGALITH, facilitating access to sites and data and keeping abreast with the team’s findings with regards to enhancing current preservation methods, besides providing important archaeological and curatorial information.

The MEGALITH Project is funded by MCST’s Fusion R&I Research Excellence Programme (REP-2023-031).

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