Assessing spatiotemporal distribution of the effectiveness of Blue-Green Infrastructure in mitigating the Urban Heat Island phenomenon in Wroclaw, Poland under the Digital Twin concept for spatial policy optimization

Modern cities are highly vulnerable to the adverse effects of climate change, primarily due to the escalating frequency of extreme weather events, including heatwaves. The current state of knowledge leaves no doubt that these effects are exacerbated by ongoing urbanization, leading to the continuous sealing of surfaces and a decrease in green areas in urbanized regions, contributing to the formation of Urban Heat Islands (UHI). These phenomena result in urban space degradation, causing economic, environmental, and demographic losses. Consequently, implementing solutions to enhance cities' resilience to climate threats should be a priority for local governments. Crucial in this context is the development of blue-green infrastructure, with a specific emphasis on micro-retention and the improvement of biologically active surfaces and vegetation habitat conditions. The implementation of such solutions, especially in the face of increasing extreme weather events, is essential for ensuring the sustainable development of smart cities.

This paper will present the results of research on the spatiotemporal distribution of the effectiveness of various components of blue-green infrastructure on a city-wide scale (including: river valleys, forests, urban parks, squares, pocket parks, and larger water bodies) in mitigating the UHI phenomenon in Wrocław, Poland. The study assesses the potential of blue-green infrastructure to mitigate the impact of heatwaves on the population most vulnerable to such threats. As an indicator of urbanized areas' vulnerability to the negative health effects of UHI, we focused on the population aged over 65. The research aims to provide crucial insights into how blue-green infrastructure can be optimized to effectively reduce UHI impacts and minimize health risks, especially within the most vulnerable age groups. This operation constitutes one of the initial stages in creating a prototype of a digital twin of the urban environment of Wrocław. The ultimate goal is to model information about blue-green infrastructure for the purpose of optimizing spatial policy in the context of adapting urbanized areas to climate change. This approach aligns with the Destination Earth initiative developed within the framework of the European Green Deal and EU Digital Strategy.

In the research, data integration was performed using various sources, including multispectral imagery from PlanetScope SuperDove, thermal data from ECOSTRESS LST, point clouds from airborne laser scanning (ALS), Topographic Objects Database (BDOT10k), and demographic data from municipal databases. Importantly, the utilized data are openly accessible and free of charge under the principles of Open Science, enabling the replication of procedures in other cities in Poland and, after identification and adjustment of relevant local data, numerous cities worldwide. In Wrocław, the project aims to provide support in creating and modifying existing and new planning documents, including local spatial development plans, the general plan, and the commune development strategy. This action supports the adaptation of local spatial policy to the growing needs of adaptation to climate change. The research is conducted within the program "Implementation Doctorate – 6th edition" by the Ministry of Education and Science.