Thermal and Water Regimes of Soils of Urban Nature-Based Solutions in Central European Context

Nature-based solutions (NbS), particularly engineered urban green infrastructure systems, increasingly represent a key pathway for enhancing urban and landscape resilience to climate change by addressing heatwaves, flooding, and water stress. Their effectiveness, however, strongly depends on soil hydraulic properties, and soil–water–vegetation interactions. This contribution presents an integrated case study from the Prague City Lab within the Horizon Europe project NBSINFRA, focusing on the role of engineered soils and long-term soil monitoring in the performance of NbS under real urban conditions.

The Prague City Lab consists of three contrasting urban sites representing peri-urban, dense inner-city, and community-oriented environments. Implemented NbS include extensive and ultra-thin green roofs, hybrid green roof–constructed wetland systems, and bioretention cells designed with engineered soil profiles. These systems incorporate layered substrates with controlled grain size distribution, organic amendments, mineral components, and recycled materials to optimize water retention, infiltration, and thermal performance. Climate analyses identified extreme heat and heatwaves as the dominant hazards affecting all sites, with intense rainfall events representing an additional stressor for urban drainage systems.

The methodological approach combines soil engineering principles, hydrological monitoring, and ecological assessment, with monitoring intensity tailored to the type of NbS. Bioretention cells and hybrid systems are instrumented for detailed observation, including near-surface and substrate temperatures, soil moisture, and water balance components. In contrast, green roofs and other NbS are monitored at a basic level using standalone automated sensors to capture substrate and near-surface temperature and water content. Laboratory analyses of substrate properties, including retention curves and grain size distribution, complement in situ measurements. Soil–water–plant interactions are further evaluated through long-term observation of plant development and evapotranspiration effects. In parallel, systematic vegetation surveys document plant species composition and ecological roles across green roofs and ground-level NbS. All datasets are stored in a centralized database, enabling consistent analysis and the development of resilience indicators.

Overall, the Prague City Lab demonstrates how integrating soil engineering principles with NbS design contributes to the resilience of urban green infrastructure.