Climate change adaptation in urban regeneration practices. The contribution of soil desealing in reducing the urban pluvial flood risk

Over the past century, urbanisation has led to increasing soil sealing and consumption, exacerbating phenomena such as the urban heat island effect and urban flooding. Combined with rising temperatures and rainfall due to climate change, these challenges threaten the environmental, social, and economic sustainability of European and Italian cities. Among climate change adaptation strategies, soil desealing – i.e., the restoration of soil permeability through the removal of its impervious layer - has emerged in the scientific literature as a promising solution for mitigating these impacts by reducing surface runoff, urban temperatures, and restoring ecosystem services and functions. This research, conducted within the Ph.D. programme in Civil Engineering and Architecture at the University of Parma, explores priorities and criteria for implementing soil desealing interventions to mitigate urban pluvial flood risk, focusing on medium-sized Italian cities. Being home to a significant portion of the European population, they serve as relevant contexts for testing and implementing innovative urban strategies, contributing to polycentric and balanced territorial development. This study examines the scientific literature and the legislative and strategic frameworks addressing soil sealing and desealing, drawing on regional instruments such as Regional Law No. 24/2017 of the Emilia-Romagna Region, alongside national and European instruments, highlighting the multi-scalar and integrated approach required to address soil desealing and climate change adaptation in urban planning for mitigating the urban pluvial flood risk. Furthermore, this research tries to contribute to the challenge of defining appropriate localisation and intervention criteria for soil desealing. An additional challenge is the identification of the relevant tools for the implementation of this actions to reduce the urban pluvial flood risk, in a context that lacks a structured national framework that relies on more or less effective local initiatives and approaches. This thesis presents a research methodology that builds upon a literature review on soil sealing, desealing, and closely related topics such as flood management. It integrates quantitative and qualitative analyses, including urban pluvial flood risk, damage, and transformation potential assessments, and the identification of strategies for involving citizens of different ages to explore their perceptions and preferences. Insights into practices for enhancing public participation in urban climate change adaptation were further enriched through research experiences at Eindhoven University of Technology and the science centre ‘AmbienteParco’. The research focuses on two case studies: Parma and Brescia. In Parma, the urban flood risk, damage and transformation potential were assessed alongside participatory initiatives such as co-design sessions, outreach activities and surveys, analysing and comparing their outcomes to define priorities and criteria for the implementation of soil desealing. Furthermore, soil desealing interventions were simulated in two urban subcatchments to complete the analyses and test the proposed approaches. The efforts of the Municipality of Brescia in promoting soil desealing, as well as the Climate transition strategy and public participation framework of the city provided a comparative lens, offering further insights into the integration of soil desealing within urban planning. This thesis concludes by offering guidelines to integrate soil desealing into urban regeneration practices, both from the administrations and citizens’ point of views.