Conference Agenda

Urban areas are faced by the impacts of urbanization and climate change, including extreme rainfall events and intensified urban heat. To address these challenges, blue-green infrastructure (BGI) is being increasingly implemented, primarily for stormwater management. However, the additional multifunctional benefits, particularly heat mitigation, are often overlooked. This study aims to quantify the heat mitigation potential of various BGI elements primarily designed for stormwater management, using three neighbourhoods from a town near Zurich, Switzerland (Fehraltorf) as case studies. Utilizing the Urban Tethys-Chloris (UT&C) microclimate model, over 20 BGI scenarios designed for stormwater management were simulated, including combinations of bioretention cells, green roofs, porous pavements, and ponds. Preliminary results show that bioretention cells and porous pavements replacing impervious surfaces at ground level provide the greatest temperature reduction during peak heat. In contrast, greening roofs and installing bioretention cells on existing vegetation leads to negligible cooling or even slightly warmer conditions. The urban district exhibited the highest potential for cooling from BGI, likely due to its larger proportion of impervious surfaces. These findings demonstrate that BGI used for stormwater management can provide heat mitigation in the urban canyon, albeit they are installed at the ground level in place of impervious surfaces.

Implementing blue-green infrastructure (BGI) is a key strategy for cities to adapt to climate change. We use an integrated modelling approach, whereby each model type is designed to predict particular performance indicators. Using the models, we analyse the potential of decoupling measures and BGI implementation to reduce urban flood risk, improve the water balance, and enhance the urban climate for the city of Innsbruck. Our results show that BGI measures, designed in accordance with Austrian regulations, help to reduce flood volumes and flooded area, while improving the water balance, particularly through increased groundwater recharge. However, evapotranspiration only increases slightly, meaning no reduction in the UTCI (Universal Thermal Climate Index) is achieved at city scale. Although greening can reduce the UTCI by up to 2.5 °C, this effect is very localised. Even with citywide decoupling of 30% of all sealed surfaces using BGI, no effect is achieved, because the change in area from sealed to greened surfaces is too small. Our results also demonstrate the significant impact of shading on reducing heat stress, confirming that the combination of water-managing BGI and shading vegetation is the most effective strategy for enhancing the resilience of urban areas to climate change challenges.

Urbanization and climate change have exacerbated many urban challenges such as flooding, urban heat islands and others. Nature-based solutions (NBS) have been proposed as nature-inspired and cost-effective solutions that provide environmental, social, and economic benefits while tackling urban challenges. This study aims to identify all possible benefits associated with NBS for stormwater management. A methodology for optimizing NBS design has been created, emphasizing local conditions and desired benefits. Multi-objective optimization using NSGA-II is employed to derive the Pareto front solution set of NBS strategies. The methodology was applied to a case study in Tivoli Park, Ljubljana, Slovenia, with different land-use types and frequent flooding problems. The hydrology-hydraulic model was built in SWMM, which was calibrated using the monitored flow. The NSGA-II algorithm takes new values for the areas of the NBS units and compares the hydrological response of the catchment with the baseline model simulation. The optimized results demonstrate that NBS strategies are effective for flood reduction, peak flow control, pollutant reduction, water reuse, infiltration increase, evaporation increase, and green space increase. This research provides a deeper understanding and explanation of the relationship between trade-offs and NBS strategies.

The integration of green infrastructure in urban environments requires reliable computational tools to analyse water retention, drainage, and hydrological interactions in green roofs and urban landscapes. This paper presents a Software-as-a-Service (SaaS) platform designed for the simulation and calculation of green infrastructure. The platform includes a calculation engine for modelling hydrological processes, a 3D visualization tool for project configuration, and an AI-powered chatbot for user support.

An hydrological simulation engine enables the modelling of water retention, runoff, and infiltration based on real-world climate data from Meteonorm (long-term) or block rains (DWD KOSTRA). The platform incorporates Building Information Modelling (BIM) through IFC import, facilitating seamless integration with architectural workflows. The 3D modelling interface allows users to configure vegetation layers, terrain modifications, and hydraulic components while receiving immediate feedback on changes.

The platform was tested for accuracy and usability using empirical validation and user studies. Results indicate that the calculation engine aligns with expected hydrological performance, and the IFC import functionality supports interoperability with existing architectural data.

As pluvial flooding intensifies under climate change, Nature-Based Solutions (NBS) offer a promising solution to mitigate flooding by capturing and reducing runoff. However, planning effective NBS for pluvial flood mitigation is challenging due to the wide range of potential implementations across a catchment and complex interactions with stormwater drainage networks. Existing target-oriented approach, while effective for rapid planning of NBS for stormwater quality and quantity control, struggles with pluvial flooding reduction objectives. We propose a framework that generates NBS strategies to meet annual average damage reduction (AAD) targets in a fast and exploratory manner. The framework employs efficient scenario exploration by screening flood volume reduction scenarios under individual design storms. It then takes a data-driven approach to identify the minimum required flood volume reduction for the desired decrease in AAD as NBS planning targets. After implementing NBS in the screened scenarios, the most probable and effective NBS strategies are selected for long-term performance assessment. A semi-continuous simulation approach is applied to reduce simulation time whilst accounting for the antecedent conditions in NBS before each flood-inducing rainfall event. This framework empowers stakeholders with clear communication on the long-term benefits of NBS implementation and offers a valuable tool for rapid NBS planning.

Climate change is expected to increase the intensity and frequency of extreme weather events in Austria. To evaluate its impact on the performance of various Nature-Based Solutions in urban areas, this study examines the water balance and cooling effects of these practices in three case studies using SWMM-UrbanEVA model. Preliminary findings reveal that the average long-term water balance and cooling effects are significantly different among the three case studies. The higher the proportion of green areas, the greater the cooling capacity – through evapotranspiration rates. A slight decrease in evapotranspiration rates on hot days is observed in all study areas, indicating reduced water availability under both near future and far future climate scenarios, compared to the historical period. Irrigation demands for green areas increase significantly under future climates, by 25 to 69% in the near future period and by 42 to 120% in the far future scenario. Analyzing water balance, cooling effects and irrigation demands of different NBS types in urban areas under the context of climate change can help to identify the most effective solutions for enhancing climate resilience. Ongoing research will focus on assessing how variants in crop factors affect the long-term water balance, cooling performance and water requirements.