Sea Level Rise Scenario for 2100 A.D. in the Heritage Site of Pyrgi (Santa Severa, Italy)

Abstract

Sea level rise is one of the main factor of risk for the preservation of cultural heritage sites located along the coasts of the Mediterranean basin. Coastal retreat, erosion and storm surges are yet posing serious threats to archaeological and historical structures built along the coastal zones of this region. In order to assess the coastal changes by the end of 2100 under an expected sea level rise of about 1 m, a detailed determination of the current coastline position and the availability of high resolution DSM, is needed. This paper focuses on the use of very high-resolution UAV imagery for the generation of ultra-high resolution mapping of the coastal archaeological area of Pyrgi, near Rome (Italy). The processing of the UAV imagery resulted in the generation of a DSM and an orthophoto, with an accuracy of 1.94 cm/pixel. The integration of topographic data with two sea level rise projections in the IPCC AR5 2.6 and 8.5 climatic scenarios for this area of the Mediterranean, were used to map sea level rise scenarios for 2050 and 2100. The effects of the Vertical Land Motion (VLM) as estimated from two nearby continuous GPS stations located as much as close to the coastline, were included in the analysis. Relative sea level rise projections provide values at 0.30±0.15 cm by 2050 and 0.56±0.22 by 2100, for the IPCC AR5 8.5 scenarios and at 0.13±0.05 cm by 2050 and 0.17±0.22 by 2100, for the IPCC AR5 2.6 scenario. These values of rise will correspond to a potential beach loss between 12.6% and 23.5% in 2100 for RCP 2.6 and 8.5 scenarios, respectively, while during the highest tides the beach will be reduced up to 46.4%. With these sea level rise scenarios, Pyrgi with its nearby Etruscan temples and the medieval castle of Santa Severa will be soon exposed to high risk of marine flooding, especially during storm surges, thus requiring suitable adaptation strategies.

Climate pacing of millennial sea-level change variability in the central and western Mediterranean

“…For this reason, it is considered a hotspot of current climate change 9 – 11 , and future warming in the Mediterranean area is expected to exceed global rates by ∼25% 12 . This may result in high sea-level rise rates compared to global averages, leading to significant losses in the environmental, cultural and economic values of Mediterranean coasts 13 . Furthermore, semi-closed basins are poorly resolved by the ~1° resolution typical of global climate models included in CMIP5/6, which are generally used to drive projections of local dynamic sea-level change 14 .…”

Climate change impacts on cultural heritage: A literature review

“…Daire et al (2012) also developed a methodology to assess the vulnerability of archeological sites, taking into account various factors, such as distance from the cliff and exposure of the site to wave action, which Shi et al (2012) also applied to the Vilaine Estuary in Brittany, France. Work has also been undertaken in other areas to identify archeological sites at risk of SLR and associated coastal impacts, notably in the UK (Cook et al, 2019; Westley & McNeary, 2015), Italy (Anzidei et al, 2020), Newfoundland and Labrador (Pollard‐Belsheim et al, 2014; Westley et al, 2011), California (Reeder et al, 2010; Reeder‐Myers, 2015), Australia, and New Zealand (Bickler et al, 2013; Carmichael et al, 2017; Rowland, 1992).…”

Pyrgi: analysis of possible climatic effects on a coastal archaeological site

“…The emerged area includes a ceremonial district and two different sanctuary areas: Monumental and Southern ( [12]. A consistent part of the area is completely submerged by the sea that includes the harbour site Over the years, the site has suffered repeatedly flooding events, characterized by a strong transport of solid sludge and permanence of water in the site, which can cause damage, delay of the archaeological excavation work, and a complete submersion of the site in the future [1]. In the area under consideration, as can be seen in Figure 1, no structures built over the ground exist, but ruins located at lower ground level, potentially transforming into large basins of water after a heavy storm and consequent floods ( Figure 2).…”