D4.4 Deterioration of the building materials under extreme events required in the CH vulnerability assessment

Cultural Heritage is today suffering under the pressure of the economic growth that triggers hazardous habits. Extreme weather events are one of the many aspects of climate change having a dramatic impact on historical areas. The evidence of this large-scale human impact needs quantification of the current effects and prevision of the future ones, modelling the possible risk scenarios. The valorisation of the historical urban texture by the cooperation between research and governance is the win-win solution to fix new planning tools and achieve multiple goals for a sustainable transformation of the cities and more resilient systems for the future generations. To this purpose, this part of the HYPERION research (D4.4) is addressed to the quantification of the tangible effects of extreme weather events on the urban context, in order to define the hazard situation and support authorities for good practises in the challenge of Cultural Heritage preservation. D4.4 focuses on the influence of extreme events on the decay and vulnerability of historical stone and brick buildings in Venice (Italy), a place that perfectly represents the fragile equilibrium between the mankind, its heritage, and the environment. Two pilot areas were selected as the main cornerstone for the field and laboratory investigations: the Clock Tower in St. Mark’s square and the church of Santa Maria dei Servi (Tier 1 and Tier 2 building, respectively); further investigations were done on carved decorations in St. Mark’s square and the church La Salute. Photogrammetric surveys, performed both on land (with a tripod) and in air (with a drone) allowed for providing 3D models, helping the detection and high-resolution study of the weathering patterns. Hyperspectral analyses, done both on field (with a drone) and in the laboratory, supported the mapping of the building materials, their collocation, and the spectral signature of their unaltered and altered composition. Finally, X-ray diffraction and colorimetric analyses in the laboratory provided complementary information about composition and surface features. The relevant results aim at detailing the climate change risk posed to coastal and lagoon environments, involving the wetting and salt weathering of building materials, due to or exacerbated by extreme floods, sea level rise, storms, coastal erosion, etc.