Interventions on Coastal Monuments Against Climatic Change

Abstract

Climate change impacts are functioning as risk multipliers to problems which are already apparent and affect cultural heritage sites. Sea Level Rise and increased storm events can damage structures that were not designed to withstand prolonged structural pressure, erosion, and immersion. Risks affecting coastal cultural heritage may stem from exposure to one or more hazards and it is important to facilitate a holistic understanding of factors driving them. Wave energy and overtopping of coastal structures represents a potential hazard for people, property and infrastructure. Especially when the coastal structure is a monument or landmark, mitigation measures and monitoring are needed. Depending on the level of acceptable risk and required degree of certainty related to wave overtopping, coastal engineers rely on predictions from semi-empirical desktop methods and numerical models for answers. Moreover, the anticipated increase in extreme events due to climatic change make protection and prevention action even more necessary. In this work the combination of risk assessment analysis related to increasing sea level and storm frequency, wave numerical modelling, breakwater design and economic sustainability is presented. As a case study, the Venetian Coastal walls of the city of Heraklion are considered. Numerical modelling results were generally found to be consistent with overtopping wave measurements. For the analysis of the wind regime in the near and far future, climatic modelling has been used. Climatic modelling results indicate that for the coastal area of Heraklion the wind speed and directions are expected to change in the near and far future, with an increase in wind speeds but also an increase in the frequency of the wind directions that effect the monuments the most. Based on the results of the measurements and numerical modelling, mitigation actions were proposed that include, increasing the submerged armouring of the Venetian City walls and the use of natural based solutions for low slope areas in order to reduce wave energy, run up and overtopping, reconstruction of the natural environment, so that the monument can be made accessible for longer periods of time.