This research explores the application of Geographic Information Systems (GIS) as a sustainable urban planning tool for flood management in the Gampaha District of Sri Lanka. It addresses the challenges posed by rapid urbanisation and increased flood vulnerability, where traditional approaches have proven inadequate in the face of complex urban development patterns and climate change impacts. While previous research has established GIS's potential in flood risk assessment and management, its application for sustainable urban planning and flood management in Gampaha District remains underexplored. This study aims to fill this gap by demonstrating GIS's effectiveness in enhancing flood management practices in the area. The research employs a mixed methods approach within a case study strategy, combining qualitative and quantitative approaches. Data collection relies on secondary sources. Analysis methods include thematic, content, and GIS-based spatial analysis using ArcGIS Pro software. Key findings reveal a strong correlation between urbanisation patterns and increased flood events in Gampaha District. The study identifies specific flood management challenges, including inadequate drainage infrastructure, encroachment on flood plains, and geographical and environmental vulnerabilities. GIS analysis provides detailed flood risk mapping with a model and identifies optimal locations for sustainable infrastructure development using the multi-criteria decision analysis (MCDA) method. The research contributes to the existing body of knowledge by offering a model that integrates GIS tools for mapping, risk assessment, and strategic planning to mitigate flood risks in rapidly urbanising areas. It provides evidence-based recommendations for enhancing flood resilience through sustainable urban planning practices such as wetland restoration, permeable pavements, rain gardens, urban forests, and floodwater pumping stations. Future work involves longitudinal studies and real-time data integration for more dynamic flood management strategies with system thinking approaches.
Key Words: Urbanisation, Flood Management, GIS, Urban Planning, and Sustainability
How to cite: Arambegedara, C. and Nwankwo, N.: Application of GIS as a Sustainable Urban Planning Tool for Flood Management: A Case Study of Gampaha District, Sri Lanka, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2, https://doi.org/10.5194/egusphere-egu25-2, 2025.
Urban flooding poses a significant challenge in high-density urban landscapes (HDULs), exacerbated by rapid urbanization, limited permeable surfaces, and climate change. Nature-based solutions (NBS) have emerged as a promising alternative to conventional grey infrastructure, offering multifunctional benefits for flood risk reduction, ecosystem restoration, and urban resilience. This study proposes a comprehensive framework integrating spatial multi-criteria evaluation (SMCE) with analytical hierarchy process (AHP) and entropy weighting (EW) methods to assess exposure, vulnerability, and adaptability factors influencing flood risks in Shenzhen, China. The study identifies key priority areas for NBS implementation and evaluates four NBS schemes based on their technical feasibility and spatial suitability. Results reveal that indices such as river network density (26.6%) and impervious surface percentage (26.5%) significantly influence exposure, while cultural heritage (31.2%) and emergency shelters (58.0%) dominate vulnerability and adaptability assessments, respectively. The prioritization map highlights critical zones requiring immediate intervention, emphasizing the need for integrated strategies addressing urban planning and socio-cultural dimensions. This research provides actionable insights for urban policymakers and planners, underscoring the transformative potential of NBS in mitigating urban flood risks and advancing sustainable urban development.
How to cite: Zhao, J. and Wang, M.: Strategic Deployment of Nature-Based Solutions for Urban Flood Management in High-Density Urban Landscapes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-323, https://doi.org/10.5194/egusphere-egu25-323, 2025.
Urban trees are essential components of urban greening efforts and in the concept of “sponge cities”, providing a multitude of ecosystem services. In recent years, there has been a renewed interest in the practical contribution of trees to stormwater management in cities. However, the representation of trees in most conventional urban stormwater models remains inadequate. Often, these models implicitly lump specific parameters of tree species as part of the general vegetation categories or pervious accounting processes. In this study, we utilized the updated SWMM tree canopy module to model and evaluate the stormwater runoff reduction potential of birch (Betula pendula Roth.) and pine (Pinus nigra Arnold) trees in three scenarios (i.e., birch, pine, mixed-species planting) on a storm event basis. The model allows for the definition of individual trees, as the added canopy module introduces several key parameters to characterize different tree species. Modelling results demonstrated that the interception routine implemented in the updated SWMM model effectively captured the temporal evolution of throughfall + stemflow (Tf + Sf) under both trees in different phenoseasons. There is also a strong correlation between the simulated and observed throughfall (r = 0.97-0.99) and interception values (r = 0.72) across all storm events. The model tends to overestimate Tf + Sf, particularly for the pine tree, resulting in an underestimation of canopy interception by 3.1% for the birch and 19.6% for the pine. Thus, the reduction in runoff volume and peak flow across all scenarios and phenoseasons in an event-based is between 20-25% and 16-25%, respectively. The mixed-species tree planting scenario performed better in reducing both runoff volume and peak flow than the single-species scenarios. However, the stormwater reduction efficiency of both trees becomes limited during intense, high-volume storm events, but they continue to provide tangible benefits. Water balance analysis further emphasizes the relative contribution of canopy interception in the stormwater runoff reduction benefits of urban trees, particularly during the leafed season, small to moderate storm events, and when trees are in directly connected impervious areas. This underscores the importance of considering rainfall interception as a critical hydrological process, especially when modeling nature-based solutions in urban environments. Moreover, infiltration and storage in the soil play a dominant mechanism in managing net rainfall under the tree canopy before it contributes to runoff, accounting for over 20% of the water balance. Importantly, the findings from our study offer valuable insights and guidance for urban planners and stormwater engineers on appropriately crediting the stormwater reduction benefits of urban trees within urban planning frameworks and policy development.
Acknowledgment: This work was supported by the P2-0180 research program through the Ph.D. grant to the first author, which is financially supported by the Slovenian Research and Innovation Agency (ARIS). Moreover, this study was also carried out within the scope of the ongoing research projects J6-4628, J2-4489, and N2-0313 supported by the ARIS and SpongeScapes project (Grant Agreement ID No. 101112738) and NATURE-DEMO (Grant Agreement ID No. 101157448), which is supported by the European Union’s Horizon Europe research and innovation programme.
How to cite: Alivio, M. B., Bezak, N., Šraj, M., and Radinja, M.: Quantifying the stormwater runoff reduction potential of two distinct urban tree species, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2754, https://doi.org/10.5194/egusphere-egu25-2754, 2025.
Urban populations face increasing heat hazards driven by urbanisation and climate change, with the impacts disproportionately affecting vulnerable groups—those with greater sensitivity and limited adaptive capacity. Urban trees can offer a practical climate adaptation strategy, mitigating heat through evaporative cooling and shade mechanisms while providing outdoor heat relief for at-risk populations. In previous research, we employed ENVI-met microclimate and WRF mesoclimate models to explore how soil moisture, built environment, and tree patch sizes affect human thermal comfort under average and extreme summer conditions in Zurich, Switzerland. Building on this work, we now present a replicable framework for global application to optimise urban tree planting locations by creating a spatial score for planting priority. The framework combines opportunities mapping, identifying areas with higher rainfall runoff or reuse water availability for irrigation, with challenges mapping, targeting zones of heightened heat vulnerability. Our work emphasises the role of water resources and the limitations of passive cooling in urban climate adaptation, while offering actionable tools for urban planners and green space managers to enhance thermal comfort for those most at risk from heat-related hazards.
How to cite: Gobatti, L., Marcus Bach, P., Maurer, M., and Leitão, J. P.: Wet soil sinks heat: spatial planning of irrigated trees to address heat vulnerabilities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2852, https://doi.org/10.5194/egusphere-egu25-2852, 2025.
Urban flooding poses a growing challenge, intensified by rapid urbanization and climate change, which strains traditional drainage systems. This study investigates the application of Low Impact Development (LID) techniques as a sustainable solution to enhance urban drainage system resilience. Using Gurugram, India, as a case study, the research evaluates the functional and structural resilience improvements achieved through LID implementation, alongside a Life Cycle Cost (LCC) analysis to assess cost-effectiveness.
LID Performance Index (LPI) was employed to quantify the functional resilience – a measure of system resilience under varying scenarios of urbanization and increased rainfall intensities. Structural resilience was analyzed by assessing reductions in vulnerable locations through one-at-a-time failure simulations. To effectively integrate the green roofs and rain gardens in the runoff management, the subcatchments with substantial impervious area and high runoff volume were designated as the potential subcatchments for LIDs’ application. The study examines four LID implementation scenarios, incorporating green roofs and rain gardens into 10% (S1), 25% (S2), 50% (S3), and 100% (S4) potential subcatchments.
The finding reveals that incorporating LIDs into 10% of potential subcatchments (Scenario S1) enhances functional resilience by 21% and reduces vulnerable nodes by 8.7%. The corresponding Benefit-Cost Ratio (BCR) for Scenario S1 is 2.05 under a 5-year return period design storm, indicating its cost-effectiveness. While increasing LID coverage improves resilience, the cost-effectiveness diminishes due to higher implementation costs.
The LCC analysis incorporates construction, maintenance, and salvage costs to evaluate the economic viability of LID practices. It highlights that LIDs are particularly effective for moderate storm events, with a noticeable decrease in effectiveness for extreme storms with higher return periods. The findings underscore the limitations of relying solely on LIDs for stormwater management, advocating for their integration with conventional drainage systems to address extreme scenarios effectively.
The insights provided in study are valuable for urban planners, engineers, and policymakers aiming to develop sustainable and resilient urban drainage systems capable of mitigating urban flooding impacts.
How to cite: Osheen, O., Gironás, J., Kansal, M. L., and Bisht, D. S.: Life Cycle Cost Analysis and Resilience Evaluation for LID Implementation in Urban Drainage Systems using SWMM, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3656, https://doi.org/10.5194/egusphere-egu25-3656, 2025.
Land use has important impacts on microclimate, especially in urban environments with complex morphology, and surface materials have different properties (e.g., colour or composition, natural/anthropogenic). Mapping microclimate regulation in urban areas is challenging since it can change over short distances. Therefore, high-resolution images are key to assessing it at a fine scale. Unmanned aerial vehicles (UAVs) are a good tool for collecting information in a detailed resolution under different meteorological conditions. In this work, we aim to map microclimate regulation in an area located in Vilnius, using a thermal UAV and land surface temperature as a proxy. The study site has an area of 104 ha. It comprises diverse land use (buildings, parking areas, equipment, roads, other paved areas, sidewalks and bike lines, construction sites, grassland and scrubland, agriculture, water and wetlands, trees and forests). Six UAV missions were conducted on July 10, 11, 14, 16, 18 and 19 of 2024, during a heat wave in Eastern Europe. The results showed statistically significant results (p<0.05) among days and land uses. The hottest days were July 11 and 16, and the coolest were July 14 and 19. Buildings and parking areas were the areas that showed the highest temperatures (>45 °C), while the lowest were identified in water and wetlands, trees and forests (<30 °C). As expected, urban green areas were the most efficient in regulating the microclimate. However, the differences between land uses were impressive for a small study area. On average, the amplitude between land uses was more than 15 °C, showing that surface type had an important impact on microclimate regulation. Even though heatwaves were not as common, frequent, and severe in this part of Europe as in the Mediterranean, this scenario has been changing in recent years, and the highest temperatures have been observed. The results obtained during this short study period showed that national and local authorities need to consider the risk of heatwaves and the implications on well-being in their plans. For this, improving urban green areas that can mitigate them is mandatory.
Acknowledgements
The work is supported by the project MApping and Forecasting Ecosystem Services in URban areas (MAFESUR), funded by the Lithuanian Research Council (Contract: Nr. P-MIP-23-426).
How to cite: Pereira, P., Pinto, L., Baltranaite, E., Gomes, E., Inacio, M., and Barcelo, D.: Land use impacts on microclimate regulation in Vilnius (Lithuania), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5050, https://doi.org/10.5194/egusphere-egu25-5050, 2025.
Pluvial floods, recognized as one of the most significant threats in urban areas lead to risks in urban water management and cause extensive damage to infrastructures and properties. Due to climate change, European countries are anticipated to experience more frequent and severe flood events. Therefore, the implementation of appropriate measures for flood mitigation is essential. Rain gardens, a type of nature-based solution (NBS), are crucial strategies to support sustainable flood risk management. However, to assess long-term impacts in light of climate change and to guide the development and implementation of additional measures in the region, the application of modeling techniques is essential. A robust modeling approach provides valuable insights for decision-making and also helps stakeholders and practitioners evaluate strategies and design future measures. This study aims to compare different modeling approaches by using FLO-2D PRO to simulate the impact of rain gardens on surface runoff mitigation. To this end, inflow and outflow data collected at the plot scale were used to compare and evaluate the outcomes of the analyzed approaches. The findings have deepened the understanding of simulation techniques for these structures, highlighting the advantages and disadvantages of different model implementations. This has enhanced the application of the model in this field, leading to more reliable results.
How to cite: Almasi, P., Bettella, F., and D'Agostino, V.: 2-D hydrological model application at Plot Scale for Evaluating Rain Garden Effectiveness in Flood Management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5606, https://doi.org/10.5194/egusphere-egu25-5606, 2025.
Green infrastructure (GI) uses different plants to deliver various ecosystem services in urban environments. Among these services, pollution control is critical due to its association with disease spread. According to The World Health Organisation (WHO), Particulate Matter (PM) is a major threat to human health from air pollution. The most effective GI mitigation application is a vertical barrier positioned between the pollution sources and receptors. Selecting suitable plants for such barriers is essential, taking into account that most of the PM occurs during winter from wood-burning heating systems.
Bryophytes, or mosses, are evergreen plants and have a high capacity for air pollution absorption due to their morphology. To identify the most effective moss species for PM absorption, a laboratory experiment was conducted at the Laboratory of the Physics and Chemistry of Environment and Space in Orleans (LPC2E-CNRS), France under the supervision of Dr. Jean-Baptsite Renard. A custom-engineered air pollution chamber was built with a vertical GI barrier inside to measure PM absorption before and after the barrier. Pollutant transport was simulated by the traction of an installed fan within the chamber. Results from the Pollutrack sensors revealed an average PM absorption efficiency of 40% for PM2.5 and 46% for PM10 based on 26 experiments using moss species Dicranum scoparium, Plagiomnium affine, and Hypnum cupressiforme. These results represent the optimal absorption capacity of mosses under controlled laboratory conditions, accounting for limitations such as humidity, air pressure, and temperature in the laboratory. This research demonstrates that mosses are a highly effective choice for the GI with a significant PM absorption potential. Further studies in real urban environments are recommended to validate these findings.
How to cite: Karklina, J. and Karklins, E.: Utilization of Mosses in Green Infrastructure for Mitigating Particulate Matter Air Pollution, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6445, https://doi.org/10.5194/egusphere-egu25-6445, 2025.
The large-scale installation of green roofs and other nature-based solutions in urban environment can provide multiple benefits for the sustainable development of cities. The implementation of these solutions, in facts, contributes to runoff mitigation during intense rainfall events, to urban heat island reduction, to biodiversity increase and to air quality improvement and it ensures an added aesthetic value. Although these solutions have been largely investigated from a technical perspective to ensure an efficient and effective installation and maintenance, it is also fundamental to evaluate citizens’ perception and willingness to pay. This aspect is crucial for policy makers and urban planners, since without societal interest and approval, these solutions are difficult to implement. In this context, we explore citizens’ interest and willingness to pay for private and public installations of green roofs and other nature-based solutions in three Italian metropolitan areas (i.e., Cagliari, Palermo and Turin), characterized by different climate and socio-economic conditions. Using an online anonymous survey, we investigated how socio-economic background and climate conditions could affect the perception of the most common environmental issues and the interest for urban nature-based solutions. Results highlighted an overall higher interest for green solutions on public spaces than on private ones. Most of the citizens are willing to financially contribute, with an average of 71 €/year, to the construction and maintenance of green roofs and nature-based solutions in public spaces, while the high costs limit the willingness to pay for green solutions on private properties. Results deriving from this study could provide essential insights for decision makers and urban planners to properly define green investments and incentivization policies, fostering the creation of sustainable and resilient cities.
How to cite: Viola, F., Pumo, D., Boano, F., Ippolito, M., and Cristiano, E.: Nature-based solutions and green roofs: are Italian citizens willing to pay? A survey investigation in three metropolitan areas, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7008, https://doi.org/10.5194/egusphere-egu25-7008, 2025.
Climate change and soil sealing are intensifying the challenges of urban stormwater management, driving the need for adaptive strategies to address evolving conditions [(Hou et al., 2020), (Hasankhan et al., 2024)]. Traditional grey infrastructures, designed exclusively to regulate rainwater flows, are monofunctional in nature. Their efficiency decreases as rainfall patterns shift leading to a greater risk of flooding. Furthermore, it does not address other urban challenges, such as the heat island effect (Menberg et al., 2013).
In response, nature-based solutions (NBS) such as rain gardens have emerged as promising alternatives. These structures help to alleviate flooding through sustainable practices. NBS also offer significant potential to create positive socio-cultural impacts by enhancing community engagement, fostering environmental stewardship, and integrating green infrastructure into urban lifestyles (De Knegt et al., 2024). However, although these systems are widely used, we still need to understand their long-term hydraulic performance under dynamic conditions (Wang et al., 2024). This research aims to address this gap by analysing the design, monitoring, and performance of a fully monitored rain garden system implemented on the campus of the Gembloux Agro-Bio Tech faculty of University of Liège in Belgium.
The system, spanning 4460 m², includes three swales and a semi-permanent retention basin. It is equipped with advanced sensors to monitor the dynamics of hydraulic flows, recording water levels (from 0.005 to 3.5 metres, ±2%) and flow rates (from 0 to 3.05 m/s, ±0.09%). These sensors, installed at key points, enable the monitoring of infiltration processes.
The system has been in operation for over two years. It manages runoff from a catchment area of approximately 1.8 hectares. This demonstrates its effectiveness in addressing local stormwater management challenges. The collected data has facilitated the development of a site-specific model, paving the way towards a better integration of nature-based solutions into urban and peri-urban projects.
The presentation will outline the concept and operation of the rain garden, its monitoring system, and the hydrological balances produced to date. These elements will highlight the key role of this type of infrastructure in the sustainable management of rainwater and its potential for meeting current urban environmental challenges.
De Knegt B., Breman B.C., Le Clec’h S., Van Hinsberg A., Lof M.E., Pouwels R., Roelofsen H.D. & Alkemade R., 2024. Exploring the contribution of nature-based solutions for environmental challenges in the Netherlands. Science of the Total Environment 929, DOI:10.1016/j.scitotenv.2024.172186.
Hasankhan A., Ghaeini-Hessaroeyeh M. & Fadaei-Kermani E., 2024. Enhancing Stormwater Management through Hydromodification Measures and Low Impact Development Strategies in Urban Areas: A Neighborhood-Scale Study. Water Resour Manage 1–19, DOI:10.1007/s11269-024-03971-0.
Hou X., Guo H., Wang F., Li M., Xue X., Liu X. & Zeng S., 2020. Is the sponge city construction sufficiently adaptable for the future stormwater management under climate change? Journal of Hydrology 588, 125055, DOI:10.1016/j.jhydrol.2020.125055.
Menberg K., Blum P., Schaffitel A. & Bayer P., 2013. Long-Term Evolution of Anthropogenic Heat Fluxes into a Subsurface Urban Heat Island. Environ. Sci. Technol. 47(17), 9747–9755, DOI:10.1021/es401546u.
How to cite: Renard, A.-C., Acrebis, J., Paulus, V., and Degré, A.: Innovative Nature-Based Solutions for Urban Stormwater Management: Insights from Advanced Monitoring and Modelling Systems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12397, https://doi.org/10.5194/egusphere-egu25-12397, 2025.
The development of urban-green infrastructures is considered an efficient nature-based solution (NBS) for C sequestration. The potential of NBS for C sequestration is often based on aboveground biomass and often overlook the contribution of urban soils. Urban soils vary from just affected by humans to fully human-made. Analysis of the spatial relationships between soil C stocks, СО2 emissions and UGI management and maintenance is necessary to support decisions in UGI planning aiming to facilitate C sequestration and contribute to achieving C neutrality. Urban Living Lab (LL) is a relatively novel but increasingly developing concept aiming to support multi-stakeholder engagement and co-production in exploring ecosystem processes and developing nature-based solutions in a real urban setting. European Commission considers LL an efficient tool contributing to soil health analysis and improvement, and Soil Deal for Europe requires establishing at least 100 LL by 2030. So far, most of the soil LL were developed in agricultural and natural landscapes, whereas urban soil and green infrastructures remained overlooked.
The research aims to develop a prototype of an urban soil living lab (USLL) to support C-smart decisions in soil construction, planning and maintenance of urban green spaces. The USLL shall be a platform for co-creation of soil constructions to support various types of NBS units (e.g., lawns, flowering herbs or rain gardens) and for monitoring their effects on C balance. Monitoring techniques include 1) measuring soil C stocks at multiple locations with further digital soil mapping; 2) analyzing soil organic matter fraction (mineral-associated and particulate organic matter fractions); 3) continuous measurement of soil respiration during the season (e.g., by gas analyzer); 4) continuous monitoring of soil temperature and moisture at multiple points by manual and autonomous sensors with extrapolation based on remote-sensing data on surface temperature; 5) assessing C sequestration in aboveground biomass based on regular mowing or Li-Dar scanning; 6) setting up long-term experiments to study the effects of management and maintenance regimes on C balance. The prototype was tested at three university campus areas located in different climate zones: Wageningen (the Netherlands), Moscow and Apatity (Russia).
Considering topsoil C stocks, ratios between mineral associated (MaOM) and particulate organic matter (POM) C-fractions and C-CO2 emissions/ soil C stocks ratio, soils under trees were shown as the most efficient in C accumulation, whereas lawns were potential C sources. Moreover, lawn maintenance caused high soil CO2 emissions which were intensified by favorable microclimatic conditions. As a result, C stocks under old lawns were lower compared to the recent ones, which was an opposite trend compared to what can be expected under natural conditions. Further development of the USLL approach will aim to support C-smart management of urban soils as a nature-based solution for climate mitigation and sustainable urban development.
How to cite: Vasenev, V., Korneykova, M., Dvornikov, Y., Romzaykina, O., Hoosbeek, M., and Mulder, T.: Towards an urban soil living lab to support C-smart management of green infrastructure, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13077, https://doi.org/10.5194/egusphere-egu25-13077, 2025.
Permeable Pavements (PPs) are a type of Sustainable Drainage Systems that reduce runoff in urban areas and the related discharge to the drainage network, thereby decreasing the risk of flooding without the need of changing the end of use of the retrofitted areas. However, uncertainty affecting their performance and the lack of a comprehensive understanding of the physical processes governing their functionality are still current issues that limit their installation.
Several numerical models have been employed to describe hydraulic processes in PPs. Typically, these models focus solely on simulating flows through variably saturated porous media using 1D and 2D approaches. However, this approach neglects or oversimplifies surface processes and their interaction with subsurface flows. The water exchange at the surface-subsurface interface is intrinsically linked to the infiltration process in the underlying soil layer. Surface runoff, when present, is influenced by the geometric and hydraulic properties of the surface as well as the local infiltration capacity.
These features can be adequately represented by Integrated Surface-Subsurface Hydrological models (ISSHMs) such as CATHY (Catchment Hydrology, Camporese et al., 2010), a spatially distributed and physically based model that jointly describes runoff and infiltration processes.
Here, the CATHY model has been used together with experiments developed in a lab facility to achieve a detailed understanding of the physical processes occurring in PPs.
The lab model was developed reproducing a 1:1 scale permeable parking lot section, 6 m long, 2 m wide and with thickness varying between 0.9 and 1 m (surface longitudinal slope of about 1.2%), enclosed within a 6×2 m2 concrete box.
The CATHY model is used to simulate the hydraulic response of the PP subjected to artificial rainfall events generated through a rainfall simulator (Lora et al., 2016). No-flow boundary conditions are imposed at the bottom and lateral sides to reproduce the impermeable concrete walls surrounding the PP. A seepage face boundary condition is assumed downstream to simulate the subsurface flow through the porous wall on the downstream side of the facility.
Data regarding the water table evolution is continuously gathered through spatially distributed sensors (tensiometers and piezometers), along with surface runoff and subsurface discharge measurements collected at the downstream end via tipping bucket flow gauges. The dataset is used to calibrate the CATHY parameters, i.e., the hydraulic characteristics of the pavement tiles and of the aggregate materials forming the filter layer package. A first set of parameters are defined according to literature review and laboratory tests on the aggregate materials.
Despite difficulties encountered in the evaluation of the parameters, the calibrated ISSHM represents a useful tool to achieve a better understanding of the physical processes characterizing PPs.
How to cite: Mazzarotto, G., Camporese, M., and Salandin, P.: Laboratory Experiments and Integrated Surface-Subsurface Hydrological Modeling to Evaluate a Permeable Pavement Performance, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18540, https://doi.org/10.5194/egusphere-egu25-18540, 2025.
As the world becomes increasingly urbanized, cities play a crucial role in addressing global challenges, including environmental sustainability and human well-being. The presence of natural green spaces in urban areas is essential for mediating the interaction between the built environment and humans, providing ecosystem services, and promoting population health and wellbeing. However, the demand for urban green spaces is often at odds with urbanization, densification, and sprawl, leading to the loss and fragmentation of urban natural areas.
In response to these challenges, the European Union has introduced a range of policies and legislations, such as the New Urban Agenda, the EU Biodiversity Strategy for 2030 and the Nature Restoration Law. Along with such initiatives Konijnendijk (2022) launched a new rule of thumb for urban forestry and urban greening: the 3-30-300 rule. The 3-30-300 rule aims to ensure that everyone should be able to see at least 3 well-established trees from their home, workplace, or place of learning; have at least 30 % tree canopy cover in their neighborhood; and live within 300-m of a high-quality public green space (at least 0.5 ha in size).
This study presents the first comprehensive evaluation of the 3-30-300 rule across 894 European cities, using recent data on urban green space distribution, tree cover density, and human settlement. The analysis reveals significant disparities in the distribution and access to urban green areas, with only 1.7% of the total population in European cities living in accordance with the 3-30-300 rule. There are no EU cities where more than 15% of the population satisfy the rule, and just 10 cities where this percentage is larger than 5%.
Our results show that there is a clear gap in the distribution and access to urban green areas across European cities. Thus, the projected urban population growth in European regions underscores the need for a paradigm shift in urban planning. The recent decade (2010-2020) has witnessed a significant increase in urban population (+16% on average) and urban area expansion (+2.3% on average) within city boundaries. However, this urban growth has not been accompanied by a commensurate increase in green urban areas and tree cover density with both indicators exhibiting stable or declining trends.
Such results highlight the need for a paradigm shift in urban planning, integrating green spaces and trees within city planning to provide ecological and social benefits, including climate change mitigation and adaptation. To address this gap, targeted financial support and coordinated strategies are necessary to ensure that vulnerable cities can secure adequate quantities of green spaces and provide equitable access to these areas, ultimately promoting more resilient and sustainable urban environments.
How to cite: Bertassello, L. E., van der Velde, M., and Feyen, L.: Bridging the Green Gap: An Evaluation of the 3-30-300 Rule in European Cities , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19320, https://doi.org/10.5194/egusphere-egu25-19320, 2025.
Sustainable Drainage Systems (SuDS) improve storm water management by leveraging surface runoff in urban areas while limiting the negative impacts. Integrating SuDS into the urban environments requires a systematic planning and design framework across various spatial scales. Existing studies have utilized GIS-based multi-criteria methods and Spatial Decision Support Systems (SDSS) to identify suitable locations for SuDS. However, these approaches are often subjective and do not account for the hydrologic characteristics of the catchment. Integrating SDSS tools with the Simulation – Optimization (S – O) frameworks has shown potential for addressing multiple storm water management objectives. Current S – O frameworks typically focus on providing solutions based on “which element” and “where to locate” or “which element” and “how much to allocate”. However, an ideal SuDS – SDSS should answer all the three questions: “which element”, “where to locate” and “how much to allocate”.
To holistically address this problem, a novel framework integrating SDSS with a hydrologic model using an evolutionary algorithm is proposed. The framework begins with the selection of appropriate thematic layers and water balance layers obtained from a hydrologic model – Soil and Water Assessment Tool (SWAT). The weights for the selected thematic layers are calculated using Normalized Mutual Information, an objective method that quantifies how well the chosen thematic layers explain the hydrologic response of the catchment. The second part determines suitable sites for SuDS elements, viz., bio-retention cell, infiltration trench, permeable pavement, rain garden, swales through spatial overlay analysis. The S – O part of the framework involves synthetic modelling of Hydrologic Response Units (HRUs) using the Storm Water Management Model (SWMM). This model is then coupled with the Multi-Layer Green-Ampt (MLGA) based SuDS modules to simulate the runoff response for selected design storms of various return periods. Finally, the optimal combination of SuDS (“which element”) and area to be allocated are determined using the Non-dominated Sorting Genetic Algorithm (NSGA – II). The framework produces pareto-optimal solutions, enabling decision-makers to evaluate trade-offs and develop policies for planning and development.
The framework is applied to the Adyar basin, covering an area of 830 km2. The optimal solutions obtained are implemented and simulated in the SWAT model to evaluate the peak flow and runoff volume reductions at the sub-basin scale. This research provides insights into how various combinations of SuDS implemented at the HRU level reduce peak flow and runoff volume at the sub-basin scale and how SuDS influence the water balance components, offering critical insights for urban planners and water resource managers.
How to cite: Sankarbalaji, A., Subrahmanian, S., Modi, K., Duraisekaran, E., and Narasimhan, B.: Development of a Multi-Criteria based Multi-Objective Simulation – Optimization Framework Integrated with Hydrologic Model and Evolutionary Algorithm for Planning, Design, and Analysis of SuDS at a river-basin scale, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19515, https://doi.org/10.5194/egusphere-egu25-19515, 2025.
This study explores the role of Other Effective Area-based Conservation Measures (OECM) in global climate governance and biodiversity conservation and proposes a systematic evaluation framework. As the global environmental crisis intensifies, traditional protected areas face challenges such as difficulties in designation, conflicts with human settlements, and exclusive management models. OECM has emerged as a complementary conservation strategy, particularly when combined with Green Infrastructure (GI). This approach not only broadens the scope of conservation but also introduces new actors, such as corporations and communities, into environmental governance. However, there remains a lack of quantitative evaluation methods to assess the effectiveness of OECM.
Using the Taipei Basin as a case study, a densely populated urban area with severe green space fragmentation facing challenges from climate change and biodiversity loss, this research develops an evaluation framework. It integrates the Gravity Index (GGG), Connectivity Index (dMtot), and Ecosystem Service Value Index (ESV_B) to quantify the ecological and social benefits of corporate investment in green infrastructure. Additionally, the urban cooling model is employed to analyze temperature changes under different OECM scenarios.
The results indicate that OECM-driven measures, especially corporate investments in green infrastructure such as urban parks and riverside green spaces, significantly enhance urban habitat connectivity, strengthen ecosystem resilience, and effectively mitigate the urban heat island effect. Among these, riverside corridors were identified as key areas for improving connectivity and cooling effects. Corporate participation in promoting OECM not only enhances the stability of ecosystem services but also fosters collaboration between corporations and communities, achieving synergetic governance among diverse stakeholders.
This study demonstrates that OECM provides an innovative solution to address urban biodiversity and climate challenges, complementing traditional protected areas and offering a new strategy for achieving global climate governance and conservation objectives.
Keywords: Green Infrastructure (GI), Other Effective Area-Based Conservation Measures (OECM), Habitat Connectivity, Ecological Resilience, Corporate Participation, Brand Value, Economic Benefits.
How to cite: Huang, Y.-C. and Chung, M.-K.: Integrating Green Infrastructure and OECM Strategies: Enhancing Habitat Connectivity and Urban Ecosystem Resilience through Corporate Participation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20139, https://doi.org/10.5194/egusphere-egu25-20139, 2025.
Drywells are extremely useful for coping with excess surface water in areas where drainage and diversion of storm flows are limited, thereby facilitating stormwater infiltration and groundwater recharge. Drywells have been used for stormwater management in locations that receive high volumes of precipitation, naturally or due to climate change; however, to date, they have not been developed in urban areas overlying karst landscapes. To test the performance of karst drywells, we constructed a pilot system for collecting, filtering, and recharging urban stormwater through drywells in karst rock. The study site is in the Judaean Mountains, within an urban residential area in Jerusalem, Israel. The infiltration capacity and the effective hydraulic conductivity (K) of the drywells were evaluated using graduated water injection tests. Additionally, we used electrical resistivity tomography (ERT) to monitor the subsurface water flow patterns from the injection wells to the surrounding karst matrix. The infiltration capacity of the drywells was up to 30 m3/hour (the maximum discharge delivered by a nearby fire hydrant) while monitored water levels in the drywells were relatively stable per grade, ranging from 7 to 39 m. Calculated hydraulic conductivities were in the range of K = 0.1-100 m/day, and K generally shows a weak inverse correlation with the rock quality designation (RQD) index, obtained from rock cores collected during the drilling of the dry wells. The ERT survey revealed the heterogeneous nature of the karst matrix, as changes in resistivity were detected only in specific flow paths. The performance of the pilot system was tested over the last three winters, during which all the diverted stormwater was successfully captured by the karst drywell. For example, during 9 days with a total rainfall of 295 mm, a cumulative volume of 45 m3 was recharged through the drywell, with a maximum discharge of 13 m3/hour. We believe that high-conductivity karst drywells together with adequate pre-treatment filtration can serve as a valuable technique for urban flood mitigation and stormwater recharge.
How to cite: Ganot, Y., Valdman, E., Moreno, Z., and Kamai, T.: Evaluating Karst Drywells for Urban Stormwater Management and Aquifer Recharge, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20457, https://doi.org/10.5194/egusphere-egu25-20457, 2025.
Water scarcity and the growing need for sustainable urban water management demand innovative solutions to recycle and reuse greywater. This study explores a hybrid green roof system that integrates constructed wetlands and green roofs, enabling onsite water treatment and irrigation. This nature-based solution proposed, and recently experimentally tested by Petreje et al. (2023) additionally incorporates sustainable materials, such as recycled crushed bricks and pyrolyzed sewage sludge for increased circularity. An extensive numerical study was done to enhance understanding of the system’s water flow and solute transport dynamics with aim to enhance and optimize the system potential in different configurations, irrigation schemes, and different climates.
The constructed wetland component was modeled using numerical modeling. First-order kinetics was assumed for BOD5 degradation, while the green roof component was modelled using HYDRUS-2D utilizing Richards' equation for water flow and the advection-dispersion equation (ADE) for solute transport. Input data included daily irrigation schedules, meteorological conditions, and measured outflow data from an existing experimental testbed. Validation of the model against measured outflow data demonstrated its reliability in replicating the behavior of the hybrid green roof system. Simulations further revealed that water predominantly flows through the green roof's bottom layer, which consists of mineral wool, highlighting the importance of this layer in directing water flow.
The numerical study was conducted for a number of scenarios defined by system size, irrigation schedule, and two types of climate (temperate and semi-arid). For selected scenarios, the sensitivity analysis of the model to parameters of the system (substrate and drainage depth, irrigation dose, and frequency) as well as characteristics of the porous media was conducted.
The outcome of the numerical study provides critical insights for optimizing hybrid green roof systems, including recommendations for ideal irrigation scenarios and appropriate size ratios between constructed wetlands and green roofs. By advancing the understanding of water flow and solute transport in integrated systems, this research supports the development of sustainable, scalable solutions for urban water recycling and improved green infrastructure.
How to cite: Wahab, R., Snehota, M., and Petreje, M.: Hybrid Green Roof System Combining Constructed Wetland and Semi-intensive Green Roof: Experimental and Numerical Study, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1074, https://doi.org/10.5194/egusphere-egu25-1074, 2025.
Changes in rainfall patterns, precipitation volumes, and the occurrence of droughts, while seemingly straightforward manifestations of climate change, have profound implications for water resource management and environmental sustainability. These changes contribute to increased pollutant loads entering river systems, heightened flood risks, and exacerbated water shortages, all of which are intricately linked to urban water circulation systems. Addressing these challenges necessitates significant investments in human resources and financial capital, with Nature-based Solutions (NbS) emerging as a key strategy to establish resilient and sustainable urban water environments. In Seoul, efforts to enhance water circulation incorporate NbS principles, exemplified by the implementation of a Low Impact Development (LID) pre-consultation system that integrates water circulation considerations into urban planning. Additional initiatives, such as the establishment of rainwater villages and the expansion of rainwater management infrastructure, further contribute to the creation of a sustainable and adaptive urban water environment. Globally, similar efforts are being advanced through NbS frameworks. A recent study in Bogotá, Colombia, sought to establish a water circulation model that integrates NbS to address the city’s unique challenges, including steep topography, high population density, and the climatic shifts driven by global climate change. The study developed a dual-perspective management model that incorporates NbS to manage routine rainwater effectively while mitigating flood risks in urban river systems. Building upon these diverse case studies, this research underscores the potential of NbS in fostering sustainable and resilient water circulation systems in urban areas. By leveraging NbS, actionable insights can be provided to improve the quality and sustainability of urban water environments in the context of climate change.
Acknowledgement
This study was supported by Korea Environment Industry & Technology Institute(KEITI) through Technology development project to optimize planning, operation, and maintenance of urban flood control facilities, funded by Korea Ministry of Environment(MOE) (RS-2024-00332378)
How to cite: Park, Y., Kim, R., Park, J., Yun, S.-L., Han, S.-J., and Kim, W.-J.: Application Directions of Nature-based Solutions (NbS) for Improving Urban Water Circulation Issues: A Case Study of Seoul and Bogotá, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2687, https://doi.org/10.5194/egusphere-egu25-2687, 2025.
Combined sewer overflows (CSOs) are relief valves built into urban combined sewer systems to prevent sewer flooding during extreme rainfall events. In recent years, it has been recognised that they are spilling far too frequently, causing significant pollution events on a regular basis. In England and Wales, the Storm Overflows Discharge Reduction Plan has set strict targets and requires huge changes in the water industry to reduce the environmental impacts of CSOs and the frequency of spills.
Green infrastructure and Nature-based Solutions (NbS) are increasingly recognized as valuable tools for mitigating CSO spills while offering additional environmental benefits compared to traditional grey infrastructure or conventional (typically capital intensive) engineering solutions. Whilst much of the focus has been on reducing impermeable inputs to sewers through urban SuDS (Sustainable Drainage Systems) or using wetlands to treat CSO spills, much less attention has been given to the potential for catchment-based solutions or NbS to reduce rural or green space runoff entering the combined sewers on the urban fringe. There is therefore a major knowledge gap in understanding where surface water from permeable surfaces could be entering the combined sewers and consequently where NbS could be applied to mitigate the problem of CSOs.
This study presents a workflow for identifying opportunity areas for catchment-based interventions or NbS to reduce rural or green space runoff contributions to combined sewers. The methodology involves GIS-based (Geographical Information System) topographic analysis to delineate sub-catchments draining towards sections of impermeable surfaces (e.g. roads) that connect to combined sewers. As a proof of concept, this approach was applied to wastewater catchments in South West England. A key data source for our analysis is Impermeable Area Survey (IAS) or Contributing Area Survey (CAS) data that define where impermeable surfaces drain to (e.g. watercourses, soakaways or combined sewers). The level of opportunity within a wastewater catchment is highly dependent on the presence of road drains that connect to combined sewers being adjacent to and downslope of rural/green spaces.
The geospatial analysis results identify areas with topographic connectivity to the combined sewers. Next, desk and field-based surveys of potential opportunity areas can indicate runoff potential and whether there is true connectivity or whether there are barriers not represented in the digital elevation model (DEM). Following the workflow, hydraulic modelling quantifies runoff contributions to CSO spill counts and volumes and the potential for field runoff mitigation through NbS. The level of potential opportunity varies greatly between wastewater catchments. In some cases, field runoff could be making a notable contribution to the volume and/or number of CSO spills. In one case study, modelling indicates that NbS could achieve approximately 45% to 80% reduction in spill volume and 30% to 60% reduction in spill duration depending on the field infiltration rate.
This approach has the potential to be used by water and sewerage companies to strategically identify opportunities to reduce rural and green space surface runoff inputs to combined sewers, through catchment-based solutions or NbS, ultimately helping to meet spill reduction targets and enhance environmental outcomes.
How to cite: Robinson, M., Kitch, J., Jackson, B., Waly, M., Peng, Z., Panici, D., and Brazier, R.: Identifying opportunity areas for catchment-based interventions to reduce runoff contributions from permeable surfaces to combined sewer overflows (CSOs), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6641, https://doi.org/10.5194/egusphere-egu25-6641, 2025.
The increasing impacts of climate change pose significant challenges for urban watersheds, necessitating effective strategies for stormwater management. This study evaluates the impacts of climate change on stormwater runoff and nutrient loads in the Sweetwater Creek Watershed, employing an integrated approach combining climate modeling, hydrological simulations, and green infrastructure (GI) optimization. Utilizing downscaled and bias-corrected data from eight General Circulation Models (GCMs) under two emission scenarios (SSP245 and SSP585), we project future changes in precipitation, temperature, and potential evapotranspiration (PET) for three timeframes: historical (1985–2014), near-future (2020–2049), and far-future (2070–2099). Projections indicate a 15%–25% increase in annual precipitation and a 2°C–4°C rise in average temperature under SSP245, with more extreme changes under SSP585, including up to a 40% increase in precipitation and a 5°C–7°C rise in temperature by the far-future period. These changes are expected to drive a 30%–45% increase in annual runoff volume and a 20%–35% rise in nutrient loads (e.g., nitrogen and phosphorus) under SSP585. The Storm Water Management Model (SWMM) was calibrated (NSE = 0.82) and validated (NSE = 0.79) using historical data to simulate hydrological processes and nutrient transport within the watershed. Using iPlantGreenS², a web-based GI planning tool, optimal GI locations and configurations were identified based on cost-effectiveness and nutrient removal efficiency. GI solutions, such as bioretention cells and vegetative swales, reduced runoff volume by 20%–35% and nutrient loads by 25%–40% in the near-future scenarios, with cost-effectiveness ratios ranging from $50–$150 per kilogram of nutrient removed. However, GI effectiveness declined by 10%–20% under extreme far-future climate conditions, emphasizing the need for adaptive designs to accommodate higher variability in precipitation and temperature. These findings highlight the critical role of GI in enhancing urban water management resilience and provide actionable insights for policymakers and urban planners.
How to cite: Alamdari, N. and Hoque, M.: Adaptive Green Infrastructure Strategies for Stormwater Management in Urban Watersheds Under Changing Climate Scenarios, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6999, https://doi.org/10.5194/egusphere-egu25-6999, 2025.
Cities face risks and pressures to meet infrastructure needs, often at the cost of natural resources. Blue-Green Infrastructure (BGI), like lakes and green spaces, serves as cities' "innate" immunity, mitigating risks like urban flooding. BGI’s flood-mitigating functions transcend administrative boundaries, requiring a catchment-based approach. Furthermore, due to India’s varied geography, the endogenous (local) and exogenous (regional or external) factors have different influences on the intensity of urban flooding in different city regions. However, current plans and policies, limited by administrative divisions, fragment BGI and weaken its flood mitigation capacity. Therefore, informed decision-making by urban policymakers is crucial for building future-proof cities.
Approach and Study Area: This study views cities as interactive layers, examining built-up intensity, city-level BGI transformations, and urban flooding hotspots. It highlights the interplay between urban densification, urban flooding hotspots, and BGI functioning in the catchment i.e. city-region. The study areas for this research are two urban agglomerations of India, namely, Pune and Bangalore. They’re among India’s 10 largest urban agglomerations. The findings from the case studies will highlight region-specific challenges and opportunities for integrating BGI into localized urban flood management strategies.
Methods and Data: The study will use a quantifiable approach by measuring the annual changes in values of three spatial indices – Normalized Built-up Index (NDBI), Enhanced Vegetation Index (EVI), and Modified Normalized Difference Water Index (MNDWI). The choice of these spatial indices is based on their ability to capture and differentiate the transformations in the complex urban fabric which are often overlooked in traditional spatial analysis. Open-access satellite data at a medium-spatial resolution i.e. 10- 30 m for the period 2000-2025 will be used for calculating the above indices. Simultaneously, the in-situ data on urban flooding will be overlayed to identify areas under high risk. Thereafter resulting in the mapping of patterns of built-up intensification, BGI configurations, and urban flooding.
Key Findings: The findings provide evidence to comment on the nature of the relationship between urban densification and BGI at the city-region scale; and its association with localized urban flooding. Using GIS-based methods and annual datasets for EVI, MNDWI, and NDBI will uncover spatial and temporal BGI trends, addressing how densification impacts BGI’s effectiveness in mitigating urban flooding. This research's findings will contribute to scientifically informed and tailored urban hazard management strategies.
Novelty and Future Relevance: Geo-information Science has emerged as a vital tool for studying spatial transformations and detailed analysis of India's rapidly evolving urban environments. This research extends the limited temporal analyses of changes in BGI and urban densification in Indian cities. Traditional spatial analyses, like land cover change detection, often miss urban complexities. By integrating annual datasets of the chosen spatial indices for the past two decades and in-situ knowledge of urban flooding, the study reveals unexplored trends in India’s urban growth dynamics.
How to cite: Gangwar, D. and Biswas, A.: Navigating Urban Floods: Spatio-temporal Analysis of Blue-Green Infrastructure and Urban Densification in Indian Cities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8002, https://doi.org/10.5194/egusphere-egu25-8002, 2025.
Rapid urbanisation and climate change have intensified the expansion of impervious surfaces and extreme rainfall events, heightening the risk of Urban Pluvial Floods (UPF). Therefore, this study aims to analyse Green Roofs (GR) as a Nature-Based Solution for UPF in Milan, Italy. The study utilises a GR dataset, which contains 53,519 data points, to identify potential places for GR installation within the municipal area of Milan [1]. Each item contains geographic coordinates and roof area. Moreover, the dataset also classifies the roofs into the type of structure, i.e., residential, industrial, and commercial buildings, etc. The Curve Number (CN) methodology in the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Urban Flood Risk Mitigation model is employed to compute the flood maps [2]. First, a baseline scenario is simulated without the intervention of GR to serve as a reference. Three intervention approaches are then devised to evaluate the efficacy of the GR in reducing the UPF hazard with varying percentages of the GR dataset implemented. Starting from 5% implementation and incrementally increasing up to 100%. Random iteration (ITE) approach is conducted initially. Second, iterations employ roofs with the highset area (AR). Finally, areas with the highest water depth (WD) are targeted first for the GR implementation. The model uses Copernicus Land Use/Land Cover data (LULC) [3] and NASA Soil Hydrological Group (SHG) data [4] as inputs. Moreover, the model also requires a CN table derived from a literature review. The baseline scenario without GR integration was compared to the scenarios to assess reductions in floodwater depth and affected area. The Probability Density Function (PDF) plot of the results indicated a randomised decrease in water depth across the ITE scenario. In contrast, the AR scenario demonstrated a more significant decrease in water depth during the initial stages. According to the PDF results, the WD scenario had better results. Therefore, to complete the risk assessment, the results from the WD scenario were integrated with exposure and vulnerability information. The JRC vulnerability function for residential buildings was used to complete the risk assessment. Although the analysis provided some useful insights, a comprehensive Cost-Benefit analysis is necessary to account for implementation and maintenance costs, with reduced risk and Average Annual Losses serving as the primary benefit for optimising the resource allocation. Finally, the study has some limitations, including the assumption of uniform rainfall across the municipal area and the model’s exclusion of water propagation effects.
Keywords: Urban Flood Risk, Green Roofs, Nature-Based Solutions, Risk-based design, Curve Number method
[1] Unità Open Data, ‘Potential green roofs in Milan’, Comune di Milano, 2016 (updated 2021-11-10), accessed 2025-01-13, http://data.europa.eu/88u/dataset/ds1446
[2] Stanford University et al., “Natural Capital Project InVEST 3.14.2.” Accessed: Sep. 02, 2024. [Online]. Available: https://naturalcapitalproject.stanford.edu/software/invest
[3] Copernicus, “CORINE Land Cover 2018 ,” 2024. Accessed: Sep. 02, 2024. [Online]. Available: https://doi.org/10.2909/71c95a07-e296-44fc-b22b-415f42acfdf0
[4] NASA, “Global Hydrologic Soil Groups (HYSOGs250m) for Curve Number-Based Runoff Modeling,” 2020. Accessed: Sep. 02, 2024. [Online]. Available: https://cmr.earthdata.nasa.gov/search/concepts/C2216864285-ORNL_CLOUD.html
How to cite: Durrani, A. O., Arosio, M., and Pregnolato, M.: Risk-Based Design for flood risk mitigation: a case study of green roof in Milan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8725, https://doi.org/10.5194/egusphere-egu25-8725, 2025.
Planting of trees in cities can have several benefits: they can store carbon, increase biodiversity, reduce urban heat and pollution, and mitigate flooding. To inform investment into tree planting as a climate change adaptation solution, it is vitally important that all these potential benefits can be outlined and understood by relevant stakeholders. Here we present a fully integrated, scalable, cloud-based modelling framework to provide such insights, built using open-source models and datasets.
Within this framework, the Green Urban Scenarios (GUS) model simulates tree growth and attempts to quantify several of these impacts including carbon storage, annual water storage, and air pollution. In order to measure the impacts of tree planting and growth scenarios on surface water (pluvial) flooding we combine the GUS model with a design storm model which allows us to quantify the impact of different tree planting scenarios on individual rainfall events, including future climate change scenarios. We then input the adjusted rainfall into a pluvial simulation flood model, the IBM Integrated Flood Model (IFM) to produce maps of estimated flood depth. Finally, we combine flood depth with OpenStreetMap data to estimate the impact to assets such as buildings, transport networks and energy infrastructure.
The models are integrated into a complete end-to-end workflow using a cloud-native, scalable modelling framework based on Kubernetes and OpenShift. Open datasets for England are used to obtain tree locations, historical rainfall data, climate projections, soil data, elevation models and land cover data and the workflow can be run for where the input data are available. We provide examples for several cities and towns in England, demonstrating how the framework enables users to quickly and easily summarise the potential benefits of tree planting scenarios for different regions, and for current and future climate change scenarios.
How to cite: Dawson, G., Dearden, C., Reusch, K., Doran, J., Butt, J., Rawat, A., Birmingham, M., Ozel, B., Treger, C., and Jones, A.: A cloud-native modelling framework to quantify the multiple benefits of urban tree planting , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8905, https://doi.org/10.5194/egusphere-egu25-8905, 2025.
As climate change continues, heatwaves and droughts are becoming more frequent and prolonged, challenging urban systems. Urban systems are built by and home to people, but they are also home to many other forms of life such as plants and animals. They include buildings and roads, but also green spaces and water management. To make urban areas resilient and livable for all in the future, we need new approaches and ideas to tackle the consequences of climate extremes such as flooding and overheating. Green spaces in particular have the potential to partially mitigate climate extremes in cities; trees cool sealed infrastructure in the summer. As part of the Urban Transformation - Towards Blue-Green Infrastructure as well as the Cool Tree project, we are generating real field data from established urban green spaces. Focusing on urban trees, we assess their health, sap flow, radial growth, fine root growth, microhabitats, tree microclimate and cooling effect on their surroundings. The tree monitoring, we present was started in early 2025 and will cover at least one growing season. It involves 45 trees of three different tree species located on research and university campuses of two different German cities Leipzig (UFZ) and Karlsruhe (KIT). We are covering two different experimental approaches with one observing the tree cooling and growth of Platanus x hispanica in parklike conditions and the second covering the physiology and cooling capacity of building and street trees of the species Robinia pseudoacacia and Tilia cordata under different irrigation regimes. The application of these irrigation schemes will show the value of investing water for already established urban trees. Finally, and overall, we aim to determine whether irrigated urban trees are healthier and cool their surroundings more effectively than their non-irrigated neighbors.
How to cite: Fröhlich, K., Friesen, J., Dev Roy, S., Benz, S., Chakraborty, T., Totzki, J., and Saha, S.: Tree monitoring as tool in urban transformation towards Blue-Green infrastructure, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10826, https://doi.org/10.5194/egusphere-egu25-10826, 2025.
Living in cities brings both social and economic benefits to people, but also exposes them to additional risks to life and health compared to living in the countryside. In the context of global climate change, adverse anthropogenic factors such as noise and light pollution, poor air quality, soil degradation and low biodiversity are compounded by the increased frequency of extreme weather events, ranging from heavy rainfall to prolonged dry spells. The effects of such events are particularly pronounced in large cities in moderate climate where such hazards were uncharacteristic only a few decades ago. The megalopolis of Moscow is a prime example. The approach of systematic implementation of the principles of green infrastructure (GI) and nature-based solutions (NbS) has already proven its effectiveness in regions with southern and soft climates. However, in regions with pronounced and long winters, the implementation of NbS is limited by a number of factors: the risk of reduced soil substrate capacity due to freezing, reduced pollutant treatment efficiency at low temperatures, and the presence of de-icing chemicals in meltwater runoff. Therefore, the main objective of this work is to adapt international standards for the creation of NbS on a local scale to the natural and anthropogenic conditions of cities in moderate climate, using the Moscow megalopolis as a case study.
The study included an experiment on de-icing salt contamination of soil for rain gardens based on a mixture of sand and loam and sand and peat under laboratory conditions. The results were focused on monitoring of agrochemical, physical and microbiological properties of soils, qualitative characteristics of leachate and the physiological state of plants. Monitoring of the experimental field rain garden was complemented by measurements of carbon dioxide emissions, field humidity, soil temperature and precipitation records, as well as analysis of the qualitative composition of snow cover and meltwater runoff. Experimental and field results related to surface runoff filtration processes were compared with modeling data obtained in Hydrus 2D. Experimentally obtained parameters of the soil-water characteristic curve (SWCC) and the results of particle size distribution analysis were used as input data for the model.
Model and laboratory values of filtration coefficients showed high convergence (R2=0.86) and did not exceed 300 mm/h for the proposed mixtures, but field measurements of filtration rate for identical soil mixtures were heterogeneous, with some replicates showing values almost 1.5 times higher. Soil substrates based on sand and loam were characterized by good water retention capacity and nutrient availability, which created favorable conditions for microbial communities. After salinization, the biomass and respiratory activity of microorganisms were reduced, and a low rate of recovery of viability after six months was also observed. Soils based on different types of sand and peat showed lower short-term salinity tolerance, but better long-term recovery, which can be explained by their lower water-holding capacity and better aeration.
The research was supported by the Russian Science Foundation project 23-77-01069.
How to cite: Romzaykina, O., Shchukin, I., Losev, A., Kozlova, E., Sergeeva, E., and Vasenev, V.: Adaptation of Soil Constructions of Nature-based Solutions (NbS) for Anthropogenic and Climatic Risks in the Conditions of the Moscow Megalopolis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11555, https://doi.org/10.5194/egusphere-egu25-11555, 2025.
Climate change is intensifying the frequency and severity of extreme hydroclimatic events such as heat waves, droughts, and heavy rainfall. These effects are particularly pronounced in urbanized areas with extensive paved surfaces and limited vegetation. Rising temperatures exacerbate urban heat islands (UHI), while heavy rainfall can overwhelm drainage systems, increasing the risk of flooding and combined system overflow. As one of the most widely applied blue-green infrastructure in urban regions, green roofs offer a promising solution to these challenges. By mitigating UHI effects and enhancing stormwater management, they can significantly contribute to urban climate resilience. Green roofs can reduce summer heat gain in buildings by up to 31% and retain an average of 87% of rainfall, with a substantial portion returned to the atmosphere. Despite their potential, comprehensive assessments of green roof adoption and effectiveness remain limited, partly due to a lack of accessible, comprehensive data on their prevalence and performance. Additionally, data tracking the development of green infrastructure over time is scarce, hindering the evaluation of policies and incentives aimed at promoting their implementation.
To address this gap, previous work by Wu and Biljecki developed “Roofpedia”, an open-source deep learning algorithm for green roof mapping and urban sustainability evaluation using satellite imagery. This model employs a convolutional neural network (U-Net) for image segmentation and has been successfully applied to satellite imagery and aerial orthoimagery data from different cities worldwide. Satellite imagery and aerial imagery collected with ad hoc campaigns can, however, be characterized by very different spatial resolution.
Acknowledging that different types of images and image resolutions can affect the feasibility and accuracy of automated green roof recognition, this research retrains and evaluates Roofpedia using imagery data of Berlin (Germany), investigating quantitatively how image platform type and spatial resolution affect the accuracy of automated green roof detection accuracy. Preliminary results show that green roof classification accuracy degrades substantially when the algorithm trained on orthoimagery with a 0.2 m/pixel resolution is transferred for application onto satellite imagery with a spatial resolution of 3 m/pixel, hampering the prediction of green roofs at this resolution. Further research will investigate how green roof classification capabilities degrade for intermediate resolutions, possibly identifying a feasibility range, along with different algorithm training and testing strategies considering combinations of image sources. This research ultimately aims to enhance the effectiveness of automated tools for green roof mapping, providing actionable insights to support urban planning, policymaking, and the broader adoption and monitoring of green infrastructure as a climate adaptation strategy.
How to cite: Cominola, A., Legrum, P. S., and Dasgupta, A.: Influence of image source type and spatial resolution on deep learning-based automated green roof recognition, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13562, https://doi.org/10.5194/egusphere-egu25-13562, 2025.
How to cite: Koopmans, M., Schwaab, J., Vicedo-Cabrera, A. M., and Davin, E. L.: Mapping heat-related risks in Swiss cities under different urban tree scenarios, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15933, https://doi.org/10.5194/egusphere-egu25-15933, 2025.
Urban surface sealing is limiting infiltration and thus increasing the formation of runoff during heavy rain events. Green infrastructure measures can be used to reduce urban flood risk by promoting decentralized infiltration, water storage and evaporation. In this study, we investigate the impact of green infrastructure on urban runoff formation, flood heights and flow velocities, and the resulting damage to buildings. Our model-based scenario analysis is located in Berlin, in a heavily sealed 3.3 km² catchment. Rain events with a duration of one hour and totals of 15 to 100 mm are considered. The green infrastructure scenarios include different spatial extents and combinations of bioretention cells, green roofs and pervious pavement. The Stormwater Management Model (SWMM) is used for the urban runoff generation and the 2D-hydrodynamic module of TELEMAC for surface runoff concentration. Building damage is modelled with the Flood Damage Estimation Tool (FlooDEsT), a recursive partitioning tool developed with survey data representative of building damage caused by pluvial floods.
How to cite: Dobkowitz, S., De Vos, L. F., Jarajapu, D. C., Lindenlaub, S., Samprogna Mohor, G., and Bronstert, A.: Scenario analysis on the impact of green infrastructure on urban pluvial flood mitigation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16859, https://doi.org/10.5194/egusphere-egu25-16859, 2025.
Green roofs provide a wide range of co-benefits, including reducing stormwater runoff, improving air and water quality, supporting biodiversity and decreasing energy consumption for heating and cooling. These features make green roofs essential for the sustainable development of smart, resilient cities. Despite extensive research on their benefits, adoption remains limited, largely due to unclear public perceptions and limited understanding of citizens' willingness to pay (WTP) for green roof installation and maintenance. Gaining insights into public interest and WTP is crucial for urban planners and policymakers to incorporate green roofs into future urban development plans.
This study examines public perceptions of green roofs and other nature-based solutions (NbS) in Edinburgh, Scotland, and assesses residents' WTP for their adoption. A survey disseminated through social media platforms and in-person flyers yielded over 300 responses. The data were analysed to identify trends in awareness, interest and WTP, associated with different socio-economic and demographic indicators.
Key findings reveal a high level of awareness about NBS and recognition of green roofs as effective solutions to major environmental challenges, such as high energy consumption, air quality issues, water retention and biodiversity loss. Many respondents expressed WTP for green roofs, particularly through council tax contributions for public infrastructure, though only 25% showed interest in installing a green roof on their own property. Barriers to adoption include unsuitable building conditions, high installation and maintenance costs, and limited knowledge about green roof implementation. More than half of respondents indicated that they felt as though their buildings were unsuitable for green roof installation or they were not in a place to make this decision (i.e. not the property owner or living in a shared block of flats where external features are managed by an external company). However, if these barriers were not present, there would be a preference for supporting green roofs on public and private spaces in cities.
Additionally, a comparative analysis with findings from an affiliated study conducted within Mediterranean regions was conducted to identify potential cultural and economic factors influencing regional variations in WTP for green infrastructure in cities. Preliminary analysis demonstrates that the perceptions on the benefits of green roofs differ, driven by differing priorities and challenges associated with regional climatic conditions (i.e. passive cooling in Mediterranean regions versus heat retention and rainfall management in Edinburgh’s temperate oceanic climate).
This study has implications for the adoption of green roofs within the UK and Europe, highlighting several barriers which need to be overcome before widespread adoption can be achieved.
How to cite: Green, D., Cristiano, E., Smith, O., and Li, L.: Awareness, adoption and willingness to pay for green roofs in the City of Edinburgh, Scotland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17332, https://doi.org/10.5194/egusphere-egu25-17332, 2025.
Due to climate change, heavy rainfall events have become more frequent and more severe. Cities like Vienna are particularly affected by the consequences due to a high degree of sealing. City planning is not in line with “water-sensitive” principles. As a result, the sewage systems are repeatedly pushed to their limits. At the same time, summer heatwaves and dry periods are becoming more intense and longer, putting massive pressure on urban vegetation.
A key aspect of creating climate-resilient cities is therefore integrative rainwater management (RWM) and implementing green-blue approaches. The planning, implementation and operation of more sustainable RWM systems often cause problems for stakeholders due to their complexity. Planning and decision support systems and BIM-compatibility for green-blue solutions are currently missing. A simple and transparent web application for planning sustainable, green rainwater management systems can fill this gap as a stand-alone-solutions as well for BIM-integration.
Solutions for decentralised and integrative green rainwater management are collected and analysed and made available via a web interface which are based on a component database from the software BIM as well as predefined and scientifically elaborated parameter-based calculations for discharge. Complex, interlinked systems of building-related retention solutions (roof and façade greening), rainwater utilisation and infiltration systems are linked together.
The aim is to create a prototype web application for planning integrative, decentralised stormwater management systems. The planning recommendations should respond to the individual project parameters. These include, for example, size and type of the area to be drained, runoff coefficients, the soil conditions and potential infiltration capacity, the available infiltration area, the rainfall measurement and other microclimatic parameters. In addition, the web application is designed to meet the specific requirements of users by taking into account preferences in terms of aesthetics, improvements of ecological and biodiversity status, of microclimate and costs.
Through this comprehensive approach, the planning tool will cover the needs of various stakeholder groups. Compared to hitherto solutions, the intended application represents a massive simplification for all users. This enhances the rethinking of urban design and more resilient urban planning. The spectrum of decentralised rainwater management will be made accessible to a broader public, thereby raising awareness and optimising and maximising the potential of green-blue RWM solutions. The interested public can get basic information and overview, planners have access to a wide range of parameter-based components and complex systems can be planned quickly and easily. This contribution presents a new approach supporting future BIM standards for rainwater retention and green-blue RWM implementation.
How to cite: Henöckl, C., Pucher, B., and Stangl, R.: Integration of green-blue rainwater management approaches into a planning and implementation tool for BIM-compatability, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19420, https://doi.org/10.5194/egusphere-egu25-19420, 2025.
Posters virtual: Mon, 28 Apr, 14:00–15:45 | vPoster spot A
EGU25-18797 | ECS | Posters virtual | VPS8
Enhancing Urban Stormwater Management: Traditional Measures versus Future PerspectivesMon, 28 Apr, 14:00–15:45 (CEST) | vPA.6
This abstract investigates the evolution of urban stormwater management, contrasting traditional methods with emerging approaches, emphasizing the integration of Low Impact Development (LID) strategies and Building Information Modeling (BIM). A comprehensive review of Scopus and Web of Science articles synthesizes existing research to identify trends, challenges, and opportunities in this interdisciplinary domain. Key insights include the effectiveness of LID practices such as permeable pavements, rain barrels, and the application of simulation tools like SWMM and HEC-RAS in reducing runoff and enhancing urban hydraulic modeling. The findings highlight the critical role of green infrastructure in mitigating rainfall impacts and the importance of cost-benefit analyses for evaluating LID implementation. Despite proven benefits, gaps persist in integrating LID into land-use planning, particularly in addressing future climate risks and accommodating urban growth. The study underscores the potential of 3D digital technologies to enhance stormwater management strategies, especially under extreme rainfall conditions. Additionally, the review identifies the lack of high-resolution data as a barrier to informed decision-making. It advocates for stronger collaboration between researchers and policymakers to foster sustainable urban development, improve water conservation, and minimize flooding risks. LID practices, integrated with Building Information Modeling offer a cost-effective solution to urban stormwater challenges, paving the way for resilient and sustainable cities.
How to cite: Fahimi, F. and Ostad Mirza Tehrani, M. J.: Enhancing Urban Stormwater Management: Traditional Measures versus Future Perspectives, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18797, https://doi.org/10.5194/egusphere-egu25-18797, 2025.
Additional speaker
- Daniel Green, Heriot-Watt University, United Kingdom