Risk Assessment of the Effects of Climate Change on Lakeshore Sites Using Earth Observation Data. The Case of the Prehistoric Settlement in Smuszewo (Poland)

Kurzfassung

Climate change is one of the factors affecting the preservation or degradation of material cultural heritage. Understanding the potential risks at the site level is essential to ensure that appropriate strategies are applied to protect the material relics. Lakeshore sites are located in an environment that is particularly sensitive to climate change. The waterlogged conditions are crucial for the preservation of fragile archaeological materials, such as those found at the prehistoric fortified settlement at Smuszewo, Poland. Archaeological surveys conducted between the 1950s and 2010s revealed well-preserved wooden structures on land and on the lake shore. However, changes in the lake environment (e.g. decreasing water levels, eutrophication, peatland drainage) may expose these relics to unfavourable conditions, leading to their exposure and gradual destruction. It is therefore crucial to understand the dynamics of lake changes, both seasonal and long-term. The EU-funded TRIQUETRA project (Toolbox for assessing and mitigating Climate Change risks and hazards threatening cultural heritage) seeks to provide tools to identify, assess and monitor these changes. Earth Observation data play a crucial role in the TRIQUETRA methodology and have been used to identify climate-related risks to cultural heritage. The initial analysis, based on gridded climate observational datasets (E-OBS dataset) and local weather stations with long meteorological records (from the mid-20th century), showed a noticeable trend in temperature increase. However, no statistically significant changes in precipitation were observed. In addition, there are no historical or recent records of in situ water level measurements for the nearby Lake Czeszewskie. These two factors make it difficult to estimate changes in water levels. Earth Observation data, characterised by high temporal resolution, provide a unique opportunity to understand the dynamics of the lake environment. Using Sentinel, TerraSAR-X and Planet datasets, we analyse the impact of observed climate changes (trends in temperature and precipitation) on seasonal and long-term lake changes. In particular, we consider the effect of increasing temperature on seasonal conditions and their influence on the material cultural heritage: decreasing snow/ ice cover in winter and fluctuations in water levels between spring and summer, including extreme events (floods, droughts, etc.). It is hoped that the results of these analyses will be used to mitigate negative changes in cooperation with the environmental agencies responsible for the recovery of natural resources.