Evaluation of archeological heritage exposure to wildfires through simulation techniques. A study case in Galicia (Northwestern Spain)

Abstract

Wildfires are one of the most prevalent hazards to which archeological sites are exposed. Wildfire regimes are expected to intensify in coming years in terms of frequency, severity and burn area, leading to an increased number of extreme wildfire events. In this context, it is essential to develop strategies for protecting cultural heritage from fires. These strategies involve exposure assessments which take inventories of cultural assets and evaluate how they would be impacted by fires. This study presents a workflow for analyzing the exposure of archeological assets to wildfires when these assets are dispersed throughout a landscape. In this study, a forested landscape with 692 granite-based cultural-heritage elements (mainly petroglyphs and dolmens) was analyzed. The workflow uses a wildfire simulation software that predicts variables related to wildfire behavior. In the study area, a total of 355 systematically distributed ignition points were simulated for both typical and atypical meteorological conditions. The output values analyzed were the flame length (FL), the rate of spread (ROS) and the fireline intensity (FLI), all variables related to the damage that the cultural elements could incur and to the feasibility of fire control. Outputs were analyzed in the immediate surroundings of archeological elements, deemed the paleointerface area. Additionally, simulations were also performed with virtual modifications to the vegetation structure in the paleointerface areas to determine whether this type of fire management strategy could help reduce the exposure of these elements to wildfires. Different behaviors were encountered in typical and atypical meteorological conditions. In typical conditions, controlling a fire would be nearly impossible in 53 % of the total paleointerface area. In atypical conditions, this was the case for 100 % of the paleointerface area. This reveals the great exposure of these archeological elements to wildfires, even in typical conditions, and indicates that fire management strategies are needed to protect them. The different results obtained also highlight the importance of considering both meteorological situations when performing exposure assessments. The results of the modified-vegetation-structure simulation revealed that fire management strategies focused on decreasing the height of shrubs, in shrub areas, and of the understory, in forested areas, can help to reduce wildfire exposure in both typical and atypical meteorological conditions. Finally, this workflow represents a tool that fulfills essential parts of a fire management plan: exposure analysis, emergency preparedness, and the design of fire reduction strategies. Specifically, this is a tool for prioritizing elements in need of management in landscapes with abundant scattered archeological elements where executing comprehensive preventive actions, although ideal, is not affordable.