Impact Assessment of Pollution and Climate-Induced Damage on Historic Centre of Rieti (Italy)

The conservation and protection of cultural heritage, seen in its broadest definition, face ongoing and new challenges as a result of the impacts of slow and extreme climate changes. Therefore, there is the need of further studies and the development of improved methods in order to support decision makers and public authorities in preparing plans to manage and mitigate the correlated risks.

The present contribution aims at analysing and assessing the impacts of pollution and climate change induced extremes on the built heritage located in the historic centre of Rieti (Italy). This research has been conducted in the framework of the Interreg Central Europe Project STRENCH (STRENgthening resilience of Cultural Heritage at risk in a changing environment through proactive transnational cooperation, 2020–2022) and the National Italian Project "Piano Straordinario di Monitoraggio e Conservazione dei Beni Culturali Immobili'', coordinated by the Ministry of Culture. First, the pollutants data (NO₂, SO₂, O₃, PM_2,5 and PM₁₀) extracted from air quality monitoring station at Rieti (IT0867A) were analysed and interpreted in accordance with the limiting values mandated by Italian law (legislative Decree 155 of 2010) for the characterization of air quality. Further, surface recession of carbonate stones for the period of 2011-2021 was calculated using Lipfert (1989) and Kucera et al. (2007) damage functions. Then, the “Risk Mapping tool for Cultural Heritage Protection” (https://www.protecht2save-wgt.eu/) was exploited: time series based on earth observation data (e.g. Copernicus C3S reanalysis and NASA GPM IMERG products), historical changes based on EOBS dataset and future hazard maps at territorial level based on outputs from regional and global climate models (EURO-CORDEX initiative) were investigated.

Obtained results reveal that a constant slight decline trend of pollutants annual average is shown over the years from 2011 to 2019. During 2020, lower values for each pollutant component were observed, partially attributed to the lockdown caused by the Covid19 pandemic. It was also observed that each investigated gaseous pollutant and PM fractions were within the limits regulated by the Italian Law.

Regarding the surface recession analysis, it was observed that it has been decreasing over the past 10 years from 2010 with slight increases occasionally. Also here, a decline in 2020 attributed to the lockdown is clearly observable. Moreover, most of particles contributing to PM can be certainly attributed to vehicular traffic, among anthropogenic sources, and are therefore in the fine fraction.

Finally, climate future projections, with spatial resolution of 12x12km, show a general increase of the changes of the extreme indices taken into consideration (R20mm and Rx5day); the biggest variations are typically foreseen for the far future (2071-20100), under the pessimistic scenario (RCP 8.5), highlighting a high likelihood of heavy rain and flooding risk in the area of Rieti.