Sheltering our treasures... to what extent?

It all started while watching the local news a few days before I had to submit my dissertation proposal. One of the headlines featured the protective shelter at Ħaġar Qim and the multitude of criticism it was receiving from the general and expert public. Immediately, I thought of tackling some of these issues in my dissertation because it would have bridged the cultural with the natural environment dimensions – a divide that is so evident and played about in geography.

One of the issues mentioned was the possibility of increasing wind speeds underneath the shelter. Although, apparently a minor problem when compared to others such as the aesthetical, rainfall and solar radiation issues, changing wind conditions beneath the shelter could in fact create a whole different microclimate, thus changing the whole environment possibly making the shelter partly more damaging.

Technical experts were arguing that, in a similar way that wind is funnelled through a door or window in draught conditions, it could be funnelled when forced to pass beneath the shelter at Ħaġar Qim. Such higher wind speeds could directly increase wind erosion with more particles bombarding the globigerina limestone of the temple. Strong winds could also accelerate the wet-dry and cool-warm cycles of the megaliths leading to weathering processes due to rapid expansion and contraction.

The easiest yet most objective way to verify this was to measure and compare wind speeds outside and inside the shelter. Wind was measured using a propeller anemometer in nine chambers inside the temple, eight points just at the boundary of the protective shelter outside each chamber and another eight points outside the shelter. Weather forecasts by the Met Office at Malta International Airport were used to measure the wind in days under four different directions with the highest velocities. After inputting this data in a geographic information system it was possible to construct a map of estimated wind speeds over the whole temple area. Such a map quickly revealed that no wind funnelling was taking place but, rather, that wind was decreasing in velocity as it enters the shelter and regains it back as it exits from the leeward side.

An exceptional case was observed in southeasterly winds in the first corridor of the temple where wind speed actually increased in this section. Considering its anomalous scenario, this could be caused by the structure of the megaliths themselves because this is the only part of the temple which is still roofed and winds coming straight from the southeast could be funnelled between the upright megaliths and the horizontal “roof” slab of the door.

It was thus concluded that the protective shelter at Ħaġar Qim is not causing increased wind funnelling but rather decreasing wind velocities while maintaining the temple’s aeration. The only increase in wind velocity was observed under very particular conditions probably caused by the temple itself.

For a better understanding of these processes, in the future one might install more permanent anemometers in different locations to provide a longer term wind monitoring while shedding light on more wind scenarios rather than the tentative worst case mentioned above.

The planting of salt-tolerant wind breakers such as the carob tree could help in controlling wind funnelling, especially in the southeast direction while landscaping the area. The fruit of such a tree could also be used to make the local carob syrup adding another attraction for the visitor.

This study was possible thanks to the bridging of several disciplines made possible by the undergraduate course in geography at the University of Malta. The course enabled me to use basic knowledge of cultural heritage, meteorology, erosion processes, geographic information systems and environmental management to come up with a study of a current issue that would make a difference in the life of future generations.

A word of thanks goes to my supervisor, John A. Schembri, and former Heritage Malta senior curator of prehistoric sites Reuben Grima for their continual support during this work.

sf1e10@soton.ac.uk

The author is reading for an MSc in environmental monitoring and assessment at the University of Southampton, United Kingdom.