This session aims to provide researchers with a platform to present and discuss the application, knowledge gaps and future research directions of urban GI and how sustainable green solutions can contribute towards an integrated and sustainable urban hazard management approach. We welcome original research contributions across a series of disciplines with a hydrological, climatic, soil sciences, ecological and geomorphological focus, and encourage the submission of abstracts which demonstrate the use of GI at a wide range of scales and geographical distributions.
We invite contributions focusing on (but not restricted to):
· Monitored case studies which provide an evidence base for integration within a wider hazard management system;
· GIS and hazard mapping analyses to determine benefits, shortcomings and best management practices of urban implementation;
· Laboratory-, field- or GIS-based studies which examine the effectiveness or cost/benefit ratio of solutions in relation to their wider ecosystem potential;
· Methods for enhancing, optimising and maximising system potential;
· Innovative and integrated approaches or systems for issues including bioretention/stormwater management, pollution control, carbon capture and storage, slope stability, urban heat exchange and urban food supply;
· Catchment-based approaches or city-scale studies demonstrating opportunities at multiple spatial scales;
· Rethinking urban design and sustainable, resilient recovery following crisis onset;
· Engagement and science communication to enhance community resilience.
Orals: Wed, 6 May, 16:15–18:00 | Room 2.44
Green infrastructure (GI) is increasingly deployed in ultra-urban environments to mitigate runoff and enhance ecological resilience, yet field evidence remains limited on how GI plants physiologically integrates short-term microclimatic stress exposure and subsequent recovery. In contrast to conventional urban greening plantings, GI plant operates within engineered soil–hydrologic systems (e.g., media properties, drainage/storage, and event-driven wetting–drying), which can decouple rainfall from plant-available water and reshape plant sensitivity to episodic heat–dryness stress. Here we investigate how temporally structured environmental exposures regulate plant performance in a functioning rain garden in Foshan, China, by pairing weekly physiological surveys with continuous high-frequency micrometeorological monitoring.
Eight plant indicators capturing chlorophyll fluorescence energy partitioning, pigment-related status, canopy structure, and leaf–air thermal coupling were measured over a multi-season observation period and analyzed against stress-relevant descriptors of the local atmospheric and radiative regime. Rather than relying on weekly averages alone, we characterize exposure in biologically meaningful time contexts that distinguish same-week forcing from preceding conditions, and we emphasize extreme- and duration-based signatures that better represent urban stress episodes. Across indicators, we observe a clear functional differentiation in time-scale sensitivity that fluorescence partitioning aligns most closely with short-term radiative forcing, whereas canopy and pigment traits exhibit stronger coupling to thermal conditions and atmospheric moisture demand and show a clear carry-over effect from earlier conditions. Extreme- and threshold-oriented descriptors consistently outperform central-tendency metrics in explanatory value, highlighting that short, intense stress periods contain information not captured by mean states.
Overall, the dominant constraints reflect a familiar radiation–heat–demand regime reported for urban vegetation, yet the engineered GI ecohydrological context elevates the importance of antecedent root-zone status and recovery potential relative to precipitation totals. These findings motivate climate-adaptive GI strategies that buffer radiative and heat–dryness extremes and enhance short-term recovery conditions through both general microclimate interventions (e.g., shading and exposure control) and GI-specific levers (e.g., media configuration, drainage/storage tuning, and recovery-aligned irrigation), while maintaining hydrological function.
How to cite: Xie, M., Jia, H., and Chui, T. F. M.: Identifying key environmental stressors shaping plant health in ultra-urban green infrastructure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7406, https://doi.org/10.5194/egusphere-egu26-7406, 2026.
Urban flooding continues to intensify globally due to the combined effects of climate change–driven extremes, unplanned settlement, and rapid urbanisation. Conventional approaches for the design of urban stormwater management structures rely on fixed design storms and fail to integrate flood consequences. In densely settled areas, there is little scope to augment existing designs to cope with climate change, demanding innovative decentralised solutions.
In this study, we extend a safe-fail, consequence-based design framework by explicitly integrating decentralised urban water management strategies within a sponge city paradigm. The proposed framework shifts the design objective from flood prevention to controlled failure with minimised flood severity, accounting for both centralised drainage networks and distributed blue infrastructure. An event-based simulation framework is developed to evaluate a wide range of extreme rainfall scenarios under present and future climate conditions, along with potential decentralised house-level water management strategies.
The method was applied to 100 cities in India that are part of the Government of India’s Smart Cities programme. Three decentralised water storage scenarios—(1) full-store, (2) constant release, and (3) smart (capacity-aware) release—were tested across all cities. The results indicate that, on average, a storage capacity sufficient to capture 10–15 mm of rainfall per unit area of the urban environment can reduce nearly 75% of the flood volume under the capacity-aware scenario. Corresponding values were 25–30 mm and 30–40 mm for the constant release and full-store scenarios, respectively.
The results highlight the potential of decentralised solutions for flood mitigation in urban areas and suggest the need for careful policy and governance interventions.
How to cite: Rohith, A.: A consequence-based safe-fail approach for decentralised urban stormwater management for flood mitigation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18745, https://doi.org/10.5194/egusphere-egu26-18745, 2026.
UK homes are increasingly exposed to summertime overheating and traffic-related air pollution, alongside growing risks from intense rainfall, biodiversity decline, and unequal access to health-supportive green space. However, evidence on the effectiveness of greening at the household boundary, where residents can implement rapid and affordable interventions in front gardens, back gardens and balconies, remains fragmented and difficult to translate into actionable guidance. This study addresses that gap by producing integrated, decision-ready evidence on the environmental and socio-ecological performance of household-scale green-blue-grey infrastructure across five outcome domains: air quality, overheating, flooding, biodiversity, and health and well-being. This study combines real-world monitoring, process-based microclimate modelling, and decision support development. A living lab network is established, comprising two front gardens, three back gardens, and one balcony, selected to represent common UK residential configurations and contrasting degrees of enclosure, surface cover, and greening potential. Multi-season monitoring captures exposure-relevant conditions, including air temperature and relative humidity, for overheating-related metrics, as well as particulate indicators such as PM2.5 and PM10, for near-boundary air quality. Complementary site surveys document features that mediate performance and enable transferability, including garden and balcony geometry, boundary permeability, surface materials and permeability, vegetation structure, and practical constraints on installation and upkeep. These datasets are used to parameterise and evaluate site-specific ENVI met models capable of reproducing observed microclimate and near-boundary air quality patterns. The validated models then support the systematic testing of alternative intervention configurations, placements, and intensities under current conditions and future climate stress test scenarios. Simulation ensembles quantify how intervention design and meteorological variability influence multi-benefit performance, while explicitly considering trade-offs, such as cooling gains from shading and evapotranspiration versus potential reductions in ventilation, or boundary sheltering effects that may alter pollutant dispersion patterns. The study provides a decision support tool that integrates environmental outcomes and DIY feasibility to guide household action. The tool links simple user inputs, including space type, exposure, and constraints, to ranked intervention options with indicative co-benefit ranges across the five environmental domains, alongside DIY factors such as cost, required expertise, space availability, maintenance burden, and an indicative cost-benefit perspective. A suite of DIY cards complements the tool by translating monitoring and modelling insights into step-by-step guidance on what to install, where to place it, and expected outcomes across air quality, overheating, flooding, biodiversity, and health and wellbeing, as well as typical installation and maintenance considerations. Together, these outputs support informed resident decision-making and provide local authorities and community partners with a scalable and consistent evidence base for promoting household-level climate adaptation.
How to cite: Sun, H., Biswal, A., and kumar, P.: Household-scale decision support for climate-resilient urban greening informed by monitoring and modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10185, https://doi.org/10.5194/egusphere-egu26-10185, 2026.
Urban flooding has increased in rapidly growing cities, indicating the necessity for sustainable stormwater management strategies. Low Impact Development (LID) strategies present potential solutions; however, assessing the collective effectiveness of various LID practices at the Indian watershed scale is complicated due to the complexity of spatial, hydraulic, and cost-related data. This study presents an integrated modeling and optimization strategy for implementing Green Roofs (GR), Rain Barrels (RB), and Permeable Pavements (PP) as Low Impact Development (LID) interventions to address urban flooding on the IIT Delhi Campus, a developing urban watershed in Delhi, India. A multi-objective optimization decision-support tool was developed by integrating the PCSWMM hydrological-hydrodynamic model with the NSGA-II evolutionary algorithm. This system aims to identify potential individual and combined LID allocation areas, taking into account both flood-reduction benefits and implementation costs. Simulations were conducted for return periods of 5, 10, 25, and 50 years to assess runoff volume, flood volume, and flood depth under ideal Low Impact Development scenarios. The findings indicate that the optimized LID strategies significantly decrease peak runoff and ponding depth. Among all LID solutions, GR demonstrated the lowest capacity for flood reduction, while RB and PP appeared to be more effective. Nevertheless, the combination of GR, RB, and PP outperformed each individual option. It was also observed that LID strategies demonstrate superior performance for lower return periods (5 and 10 years). However, performance decreases as rainfall intensity increases. The proposed framework offers significant insights into urban stormwater planning, illustrating how optimized LID allocation improves hydrological performance while reducing costs. This tool effectively aids hydrologists and urban planners in maximizing environmental and flood prevention benefits through the strategic selection and location of LIDs in rapidly urbanizing areas.
Keywords: LID, Optimization, Urban flooding
How to cite: Mallik, A. and Dhanya, C. T.: Evaluating Performance of Individual and Combined LID Strategies for Urban Flood Reduction: An Integrated Modelling and Multi-Objective Optimization Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4199, https://doi.org/10.5194/egusphere-egu26-4199, 2026.
We present evidence from long-term field-scale test environments in the United Kingdom, drawing on work from SuDSlab at the University of Hull and the Defra-funded Doncaster, Immingham and Grimsby Surface Water Resilience Project (DIG). Together, these initiatives employ a ‘Rain to Drain’ approach that tracks water from rainfall, through soils and sustainable drainage systems (SuDS), into drainage networks at catchment scale. Rain gardens, swales, ponds, permeable surfacing, retrofit downpipe interventions, and combined sewers have been monitored for up to four years. More than 2,000 internet-connected discrete sensors record meteorological, hydrological, and hydraulic variables continuously at five-minute intervals with live, real-time data acquisition.
High-resolution monitoring reveals several behaviours that are not apparent from design calculations or short deployment studies. Soil moisture profiles measured to depths of 0.6 m show that infiltration and storage capacity vary substantially with depth and season, with near-surface horizons responding within minutes of rainfall, while deeper layers may respond only during prolonged or intense events. Some systems operate primarily as infiltration features during drier periods, but transition to storage and attenuation dominated behaviour during wetter months. Event-based monitoring of retrofit planters and rain gardens shows delays in peak outflow of 10 to 60 minutes, with reductions in peak discharge commonly between 30 and 60% at asset scale. Downstream sewer measurements indicate that, under certain conditions, these effects can translate into longer response times and reduced short duration peaks at network scale. Monitoring also highlights important mismatches between assumed and actual system behaviour, including differences of tens of percent in contributing areas and inflow volumes between nominally similar assets.
Our work shows that long-term, high-frequency monitoring fundamentally improves understanding of how SuDS function in practice. By capturing seasonal variability, event-scale responses, and links between assets and receiving networks, monitoring provides evidence that can be used to refine design assumptions, support model validation, and diagnose underperformance. Sustained monitoring is essential not only to demonstrate that SuDS work, but to understand when they work, why performance varies, and how future schemes can be designed and managed more effectively.
How to cite: Osborne, Wm. A., McLelland, S., and Thomas, R.: From Rain to Drain: Field-scale monitoring of sustainable drainage systems (SuDS), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2557, https://doi.org/10.5194/egusphere-egu26-2557, 2026.
Mountainous regions that were safe zones are becoming increasingly vulnerable to climate-induced stressors, like flooding, landslides, and ecosystem degradation. In this debate, Swat; the northern mountainous district in Pakistan is also not an exception, which is hit hard by the climatic shocks, leaving behind devastation. To cope with the problems, Nature-Based Green Infrastructure (NBGI) as a people-centred approach, has emerged as an ecosystem-based adaptation and mitigation strategy to enhance cities' resilience against ever-rising climatic hazards. NBGI planning proves to be a vital element, not only in strengthening social-ecological connections between urban rural and mountainous areas, but also promoting the establishment of a balanced equilibrium between human-centred and eco-centred activities, thereby fostering sustainable livelihoods. Although, NBGI solutions are widely applied generally in the city settings, however, its potential to address the climatic hazards in mountainous regions still remains underdeveloped. It is particularly true for the developing countries, including mountainous regions of Pakistan. This study addresses the dire need for context-specific, proactive, pragmatic and (most importantly) the participatory Urban Landscape and Urban Greening (UL-UG) policies and strategies (tailored to the local built environment) for resilient land-use planning, as well as frameworks, to protect the inhabitants and ecosystems in the Swat district — a high-altitude, climate-sensitive region in Khyber Pakhtunkhwa, Pakistan. This research aims to determine and assemble sustainable green infrastructure (GI) planning indicators and their spatial functional linkages with the multifunctional green spaces (GS), based on the perspectives of local mountainous communities. It is to develop a sustainable GI indicator framework model under a community-led participatory (CLP) approach, best meshed with the mountainous region's built environment — makes it a unique and novel study.
The in-depth community-led survey was executed in Swat district, particularly targeting the climate effected regions across the Swat River. This empirical investigation was conducted through a self-administered questionnaire, themed around GI, resilience, and climate change adaptation, with 325 participants. The data is analysed using the Relative Importance Index (RII) and Interquartile Range (IQR) techniques, demonstrating strong internal reliability (Cronbach's α > or ≥ 0.7). The finding established potential twenty-two (primary and secondary) sustainable UGI indicators, classified into five levels: extremely important, important, moderately important, slightly important, and Low. Subsequently, a set of vital taxonomies of GS elements that achieved (RII value ≥ 0.68) were identified that strengthen the functional linkage and resilience of the respective UGI indicators when confronting environmental hazards in a mountainous region. The study concludes by advocating for a context-sensitive, community-driven UGI framework as a pathway toward an eco-friendly, climate-resilient mountainous community. This study also simulates results demonstrate the need for an inclusive perspective when building the nature-based adaptation and mitigation strategy (and standards) that will be most suitable for ensuring climate-resilient mountainous regions.
Key word: Sustainable green infrastructure (GI) indicators; green space (GS); mountain eco-system; resilience: community-led participatory (CLP) approach; climate change; Swat Pakistan
How to cite: Rayan, M., Gruehn, D., and Khayyam, U.: Climate Resilience through Community-led GI Framework in neglected Mountainous Ecosystems of Swat, Pakistan., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2764, https://doi.org/10.5194/egusphere-egu26-2764, 2026.
Rapid urban expansion in peri-urban regions presents critical challenges for sustainable water management, thermal regulation, and air quality. Urban wetlands, which are integral to Blue–Green Infrastructure (BGI), deliver essential ecosystem services such as stormwater retention, microclimate moderation, and pollution mitigation to the local area. However, these systems are increasingly threatened by unplanned land-use change and anthropogenic pressures.
This study examines wetland degradation and its implications for urban micro-climate regulation in the rapidly urbanizing peri-urban landscape of Barasat, West Bengal, India. A multi-temporal land-use/land-cover (LULC) analysis was conducted with data between the year 1995 and 2025; using Landsat 5 TM and Landsat 8 OLI imagery processed with FLAASH atmospheric correction. Changes in vegetation, surface water, and built-up areas were quantified, and their relationship with land surface temperature (LST) and air quality indicators was assessed.
Initial results suggest a significant transformation in: vegetation cover, which declined by 1,512 ha, surface water bodies reduced by 22 ha, while built-up areas expanded by 813 ha. These changes correspond to rising LST, with built-up zones exhibiting mean winter daytime temperatures of ~33 °C compared to 30 °C in agricultural areas, 25 °C in vegetated zones, and 24 °C over water bodies—highlighting the thermal regulation role of wetlands. Air quality monitoring indicates PM2.5 and PM10 concentrations driving AQI values up to 190 (moderate–poor) in dense urban areas, whereas wetland-dominated zones maintain AQI ~50 (good).
In the long term, wetland degradation compromises urban water storage and drainage, exacerbates heat stress, and increases exposure to pollution. This study advocates for Nature-Based Solutions (NbS) to restore and protect urban wetlands as functional BGI. A Living Lab framework is proposed which serves as a platform for the real-world experimental platform to codesign evidence-based restoration, ensuring NbS interventions are specific to the context, location, and socially acceptable. Within this context, the approach enables continuous multi-parameter monitoring, adaptive management, stakeholder engagement, and evidence-based restoration—supporting integrated urban water management and microclimate amelioration in rapidly urbanizing regions of the Global South.
Keywords: Urban wetlands, Blue–Green Infrastructure, Nature-Based Solutions, Living Lab, Remote Sensing, urban microclimate, wetland degradation.
How to cite: Mis, N. B., Dhali, B., Bhadra, T., Bandyopadhyay, N., Samanta, K., Hifajat, K., Kundu, R., Dutta, S., Bhattacharya, S., and Nagabhatla, N.: Nature-Based Solutions for Urban Resilience: Remote Sensing assessment of wetland degradation and microclimate regulation using a Living Lab Framework in peri-urban India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14084, https://doi.org/10.5194/egusphere-egu26-14084, 2026.
Urban areas increasingly face compound hazards linked to climate change, including intensified pluvial flooding, heat stress and water scarcity. As a result, cities are turning towards green infrastructure (GI) and nature-based solutions (NbS) that can simultaneously reduce risk, enhance urban livability and enable circular resource management. In this contribution, we present alchemia-nova’s experiences from implementing and monitoring two building-integrated vertical NbS for decentralized water treatment and reuse: the vertECO® vertical constructed wetland system at the eco-community Cambium (Fehring, southeastern Austria) and the GRETA™ modular green wall at the St. Quirze social housing pilot (Barcelona metropolitan area, Spain).
At Cambium, vertECO® was installed in a wintergarden and represents, to our knowledge, the first full-scale vertical green wall receiving all fractions of mechanically pre-treated domestic wastewater (including blackwater, and not only greywater), with the aim of water and nutrient reuse in local agriculture . The system consists of four parallel (each 2-m long) modules with four stepwise aligned, aerated subsurface horizontal-flow basins, followed by treated water storage and ozonation recirculation . Monitoring results demonstrate that vertECO® alone already achieved average effluent quality compliant with the EU water reuse regulation thresholds for reclaimed water quality Class C (drip irrigation), while vertECO® combined with ozonation achieved Class B (broader irrigation methods), also meeting local Austrian permit requirements . The wintergarden setting maintained operational temperatures above freezing conditions during the monitoring period, supporting year-round performance in a temperate climate with cold winters.
In parallel, the GRETA™ pilot at St. Quirze demonstrates a vertical green wall for residential water management, combining bathroom greywater (three showers and two sinks) with rainwater harvested from a 120 m² roof area. The system was integrated into a renovated social housing building with dedicated greywater separation, highlighting the value of implementing source separation during new construction or refurbishment. GRETA™ treats ~125 L/day (peaks up to 180 L/day) using four parallel treatment lines across four stages of horizontal subsurface flow through modular planted units. Treated water is collected, disinfected via ozonation, and reused for toilet flushing in four apartments, with emergency tap water feeding options to improve reliability.
Monitoring from May 2023 to October 2024 (15-day intervals) indicates consistent performance, including strong reductions of turbidity, suspended solids, organic load, and ammonium. Hygiene indicators were already low in the influent and reached non-detectable levels after treatment and ozonation, supporting compliance with Spanish reuse requirements for urban non-potable applications. The pilot also yielded operational lessons: elevated installation reduced vandalism risk, and a heat period combined with automation failure caused major plant die-off. However, the system recovered quickly and maintained stable treatment efficiency, highlighting vertical GI resilience under disturbances.
Across sites, we show how vertical GI can contribute to integrated urban hazard management by reducing freshwater demand, strengthening resilience to drought and shortages, supporting rainwater buffering strategies, and acting as visible, community-facing infrastructure. We conclude with key research needs on scaling, cost–benefit assessment including co-benefits (e.g., greening and cooling), long-term robustness, and governance models for operation and maintenance.
How to cite: Hartl, M., Vobruba, T., Riva, M., Bertino, G., Gattringer, H., Pueyo, J., Buttiglieri, G., Comas, J., and Wirth, M.: Vertical Green Walls for Urban Water Resilience: Lessons from vertECO® and GRETA™ Pilots in Austria and Spain, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22107, https://doi.org/10.5194/egusphere-egu26-22107, 2026.
Slope stabilization is essential for hazard management and plays a crucial role in preventing landslide events while also contributing to environmental protection. Effective protection of slopes is vital, as it not only ensures the safety of structures but also helps maintain the ecological balance in the surrounding areas. To address the challenges posed by steep slopes, soil bioengineering techniques are employed to mitigate surface water erosion and control the movement of soil masses. These techniques are particularly important in areas where the risk of erosion and landslides is heightened.
The present study aimed to evaluate the effectiveness of emerald grass rugs (Zoysia japonica) as Green Infraestructure (GI) in providing protection and stabilization for slopes based on investigation in experimental plots. The research was conducted on a steep 60% slope located at the Federal Rural University of Pernambuco State in Recife, Brazil. The experimental plots were designed with an area of 10.35 m², featuring dimensions of 3.0 × 3.45 m, and were bordered by masonry walls to control the experimental conditions. At the lowest point of each experimental unit, a 100 mm drainage pipe was installed to collect runoff and sediments, ensuring proper storage in 500-liter PVC tanks. An automatic rainfall gauge was set up on-site, providing critical data for the study.
Several treatments were implemented during the experiment: the first involved the installation of grass rugs with four replicates; the second treatment consisted of grass rugs with an underlying application of coconut powder as a bioretention layer, which had two replicates; and the final treatment served as a control, consisting of bare soil. The parameters evaluated throughout the study included rainfall, runoff, sediment loss, and erosion rates. The results indicated that for all rainfall events, the control plot exhibited a Runoff Coefficient of approximately 60%. In contrast, the grass rugs demonstrated a significantly lower coefficient of around 28%, while the grass rugs with coconut powder showed an impressive reduction to about 16%.
When examining erosion specifically, the grass rugs proved to be highly effective, exhibiting approximately 500 times less soil loss compared to the bare soil control plot. Moreover, the addition of coconut powder beneath the grass rugs further enhanced their protective capabilities, resulting in nearly 1000 times less soil loss when compared to conditions of bare soil. These findings clearly highlight that vegetation cover associated to a bioretention layer plays a vital role in maintaining the integrity of soil structure. Among the treatments tested, the arrangement of grass rugs combined with the underlying application of coconut powder was identified as the most efficient Nature-based Solution NbS method for slope stabilization and erosion control, demonstrating the potential benefits of integrating bioengineering practices into construction and environmental management strategies.
How to cite: Montenegro, A., Figueiroa, A., Lopes, I., and de Lima, J.: Bioengineering in slope stabilization: experimental evaluation of grass rugs as a Nature-based Solution for Sustainable Management, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6841, https://doi.org/10.5194/egusphere-egu26-6841, 2026.
Posters on site: Wed, 6 May, 14:00–15:45 | Hall A
Nature-based solutions (NbS) that combine vertical greening with stormwater management are increasingly deployed in dense urban environments; however, key hydrological processes, including storage, overflow pathways, and evapotranspiration, remain poorly quantified. Compared to conventional horizontal NbS, vertical systems are subject to distinct hydrological constraints related to boundary conditions, flow patterns, and geometry, yet appropriate process-based modelling approaches remain underdeveloped.
This study presents a physically based numerical framework for the conceptual representation and analysis of the hydrological behaviour of a freestanding green-screen nature-based solution using the HYDRUS-2D/3D software. The investigated NbS consists of a vertically oriented mineral wool wall that receives roof runoff at its top and is positioned above a stepped, open-bottom planter box with vegetation, hydraulically connected to the underlying native soil. The system is designed to temporarily store incoming roof runoff within the vertical wall and vegetated planter, with stored water gradually depleted through evapotranspiration and infiltration to the underlying soil.
A representative two-dimensional cross-section is used to simulate variably saturated flow, water storage, evapotranspiration, and infiltration processes within the system. Roof runoff is represented as a time-variable inflow applied at the upper boundary of the vertical wall. Atmospheric boundary conditions are imposed on exposed vertical and horizontal surfaces to represent evaporation from the wall and evapotranspiration from the vegetated planter. To address the challenge of vertical evaporation, atmospheric forcing is spatially varied along the wall to account for differences in solar exposure. Hydraulic continuity is assumed between the open-bottom planter and the underlying soil, allowing infiltration into the subsurface.
Event-based simulations are used to investigate system responses under different rainfall conditions, including wet and dry extremes, evaluate the restoration of retention capacity between successive storm events, and assess and optimise key design parameters such as wall height, planter geometry, and hydraulic properties of system materials with respect to stormwater retention and system recovery. Particular attention is given to the role of spatially variable vertical evaporation from the wall, and evapotranspiration from the planter, in controlling system recovery and overall stormwater retention performance.
The proposed HYDRUS-2D conceptualisation provides a quantitative tool for evaluating and optimising vertical green-screen NbS and supports their integration into quantitative urban stormwater management and climate adaptation strategies.
This work is carried out within the framework of the GreenStorm project, funded under the Driving Urban Transitions to a Sustainable Future (DUT) Call 2022.
How to cite: Morianou, G., Soulis, K. X., Palli-Gravani, S., Ntoulas, N., Danuta Lausen, E., Bergen Jensen, M., Berthier, E., Palla, A., and Gnecco, I.: Hydrological modelling of vertical green-screen nature-based solutions using HYDRUS-2D, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5315, https://doi.org/10.5194/egusphere-egu26-5315, 2026.
Urbanisation reduces permeable surfaces and increases susceptibility to surface water (pluvial) flooding. Nature-based Solutions (NbS) and Green Infrastructure (GI) have emerged as key components of sustainable flood risk management, complementing conventional grey systems through hybrid designs that enhance resilience and deliver multifunctional benefits. Sustainable Urban Drainage Systems (SuDS) are a prominent example, integrating the four design pillars of water quality, water quantity, public amenity and biodiversity by capturing and attenuating stormwater before it reaches combined sewer outflows (CSOs).
This study evaluates the hydrological performance of urban bioretention rain gardens across multiple sites in Edinburgh and Glasgow, Scotland. A combination of desk-based site characterisation, in-situ hydrological and hydraulic testing and distributed environmental sensor networks are used to establish baseline behaviour and storm response. These networks include volumetric water content sensors to quantify soil water storage, attenuation and drainage capacity, alongside local meteorological measurements to characterise inflow and evapotranspiration dynamics.
To assess system performance under high-intensity rainfall, controlled storm events are simulated using a portable rainfall simulator developed for site-based SuDS stress-testing. Sixty-minute design storm profiles of varying magnitudes (10-, 30-, and 100-year return periods) are applied to standardised 1 m² test plots isolated by custom-built separator trays. This setup enables consistent cross-site comparisons and links hydrological mass balance responses to site-specific conditions such as soil texture, infiltration rate, vegetation structure and planting density.
Preliminary findings demonstrate that vertical soil moisture dynamics during simulated storm events, reflecting the combined influence of soil hydraulic conductivity, antecedent moisture and vegetation cover on infiltration and retention. Measurements from sensors installed at 0–40 cm depths show rapid wetting of surface layers followed by delayed responses at depth, consistent with progressive infiltration through the soil profile. Under moderate (10–30-year) storms, soil columns exhibited sustained storage increases and slow drainage recovery, indicating effective attenuation of runoff generation. Under more extreme (100-year) events, near-surface layers reached saturation thresholds rapidly, producing short-term ponding and reduced percolation efficiency. Despite this, the monitored profiles retained measurable storage potential compared with non-vegetated controls, demonstrating capacity to buffer surface flow during extreme rainfall.
These findings provide empirical evidence on the hydraulic resilience of current NbS implementations to extreme pluvial conditions. These insights will inform design optimisation and future-proofing of rain gardens and related SuDS elements, supporting the development of more resilient and multifunctional urban drainage networks that safeguard both communities and infrastructure.
How to cite: Cheng, E., Green, D., Demyanov, V., Peskett, L., and Archer, N.: Quantifying the Hydrological Performance of Urban Rain Gardens under Simulated Extreme Storm Events , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14105, https://doi.org/10.5194/egusphere-egu26-14105, 2026.
The Gradaščica River catchment is a small torrential catchment (≈160 km²) in central Slovenia, with mainly forested and agricultural land, entering the urban area of Ljubljana in its lower reach. It is one of the case studies of the European SpongeScapes project, which aims to enhance the ‘sponge’ function of soils, groundwater, and surface waters. The project combines field measurements, upscaling, and hydrological modelling to improve catchment resilience to floods and droughts. Since 2014, a research plot has been established in the catchment to monitor precipitation interception, throughfall, and stemflow of deciduous and coniferous trees, as well as their effect on local water balance. These data were upscaled and used to model the influence of forest cover on the water balance of the catchment. A Wflow SBM model with 200 m resolution and an hourly time step, driven by precipitation, air temperature, and potential evapotranspiration, was developed to simulate hydrometeorological extremes (e.g., floods and droughts) of varying magnitude and to assess the impact of forest share, type, and location on catchment hydrology.
Acknowledgements: The authors would like to acknowledge the financial support provided by the European Union’s Horizon Europe Research and Innovation Programme, within the scope of the project “SpongeScapes” (Grant agreement No. 101112738). The study was also partially financed by the Slovenian Research and Innovation Agency (ARIS) within the research program P2–0180 and project J2-4489. The research is also supported by the UNESCO Chair on Water-related Disaster Risk Reduction and the Slovenian national committee of the IHP UNESCO research programme.
How to cite: Kuzmanić, T., Zabret, K., Lebar, K., Šraj, M., Koprivšek, M., Petan, S., and Kopač, A.: From plot measurements to catchment modelling: Forest role in coping with floods and droughts in the Gradaščica River catchment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10701, https://doi.org/10.5194/egusphere-egu26-10701, 2026.
Climate change is leading to rainfall events increasing in intensity and frequency. However, traditional drainage infrastructure, such as drains and pipes, struggle to cope with this change resulting in urban areas experiencing increased surface water flooding intensity and occurrences. As a result of this, Newcastle City Council launched Blue Green Newcastle (BGN), a scheme designed to help prevent flooding while also providing wider benefits to support communities by using nature.
Trees are commonly introduced to urban areas as one form of blue-green infrastructure. To explore the interaction between trees and water, a rain garden containing a Alnus glutinosa Imperialis (Cut Leaf Alder) has been instrumented. Sensors include a sap-flow-meter, which allows water uptake to be established. The tree currently being monitored is located in a rain garden which has soil-water content sensors and water potential sensors (to understand plant water availability). These additional sensors help map the flow of water while also allowing the impact of the rain garden to be factored into the evaluation of the tree contribution to managing water through-flow. All sensors on site and the monitored weather conditions, including rainfall and temperature, help reveal the relationship between the tree, soil and atmosphere. Monitoring was setup on 19/08/25 and will run for 3 years to provide empirical evidence of how the tree-rain garden system responds to a range of seasonal (natural) and augmented rainfall conditions. Furthermore, the impact the tree has on surface water flooding during different conditions can be understood more through further modelling.
To best capture the characteristics of trees within an urban space and to support the further introduction of trees through projects like BGN, more sites will be monitored. These sites will explore trees of various ages, species and at different site types aiming to explore the impact these changes have on performance. The performance of the different monitored sites including within open spaces and tree pits can be compared against each other. Since projects that will most benefit from this evidence, including BGN, have many stakeholders, including water companies, local government and those who live, work and visit the area, exploring a wider range of site types is beneficial. Therefore, extrapolating this knowledge and evidence by using models and using the collected data to verify them is beneficial. Evidence-based guidance will ensure findings based on the data collected is accessible and supports stakeholders to deliver effective city-scale green infrastructure schemes, helping to reduce surface water flooding and the impact of rainfall events while improving the built environments for communities. Overall, this research provides a pathway for projects like BGN to lead in climate-resilient urban design where every tree planted becomes an active part of the city’s drainage network.
How to cite: Tate, M., Stirling, R., Walsh, C., Varley, D., and Hodgson, C.: Urban Trees and Flood Resilience: Monitor, Evaluate and Optimise., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-717, https://doi.org/10.5194/egusphere-egu26-717, 2026.
As extreme cold surges become more frequent in mid-latitude cities due to climate variability, the role of nature-based solutions (NBS), primarily designed for summer heat mitigation, requires re-evaluation for winter conditions. This study investigates the impact of urban street trees on pedestrian thermal comfort during a cold wave event in a high-density district of Daegu, South Korea. Using a Computational Fluid Dynamics (CFD) model coupled with a solar radiation model, we quantified the opposing physical mechanisms of trees: the beneficial reduction of convective heat loss via aerodynamic drag versus the detrimental reduction of solar gain via shading. Our results reveal that wind speed, rather than air temperature or mean radiant temperature, is the dominant driver of wintertime outdoor thermal comfort (UTCI). Tall evergreen trees significantly mitigated cold stress in wind-exposed corridors by acting as effective windbreaks. However, in already sheltered areas where solar access is critical, the shading effect of evergreens blocked valuable winter sunlight, paradoxically exacerbating cold stress by lowering the mean radiant temperature. Deciduous trees showed negligible impacts due to their low leaf area index in winter. These findings highlight that "beneficial summer shade" can become a "winter penalty." Consequently, we propose a context-specific planting framework for climate-resilient urban design: prioritizing wind mitigation in exposed zones while preserving solar access in sheltered environments.
How to cite: Kang, G. and Kim, J.-J.: Urban Tree Planting Strategies for Winter Cold Surges: A CFD-based Assessment of Deciduous vs. Evergreen Effects, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3389, https://doi.org/10.5194/egusphere-egu26-3389, 2026.
With increasing pressures from climate change and urban expansion, the development of resilient “sponge cities” is essential to mitigate flooding and reduce pollution. Rain gardens represent a key green infrastructure intervention and have the potential to be implemented far more widely in new developments or retrofitted into existing ones. Rain gardens are particularly appealing to urban planners because they can deliver multiple co-benefits by enhancing biodiversity and amenity while achieving water management objectives. However, gaps in the understanding of rain garden hydrology remain a barrier to widespread adoption. In contrast to grey infrastructure, which is supported by extensive empirical research, confidence in the hydraulic performance of vegetated systems remains limited. To embed rain gardens more effectively in urban design, their hydrological functioning must be quantified more accurately and design parameters refined.
A major source of uncertainty lies in the behaviour of rooted soils. Recent studies highlight that root-oriented preferential flow can substantially increase soil hydraulic conductivity, reduce surface runoff and prevent sediment from clogging drainage structures. Plant roots may also improve soil water retention, enhance rainfall interception, attenuate peak flow and support pollutant removal. Yet despite this growing awareness, these mechanisms remain poorly quantified and are rarely represented in models of green infrastructure. As a result, current engineering design typically relies only on physical soil parameters, without accounting for dynamic plant–soil interactions.
This study investigates the influence of root-oriented preferential flow on rain garden hydrology through a mixed-methods approach combining laboratory experimentation, field observation and mathematical modelling. The first phase involves single-plant mesocosms in a three-year longitudinal laboratory study of rooted soil hydrology, complemented by regular MRI imaging to capture root architecture development. This study presents initial findings from this longitudinal experiment, demonstrating how high-resolution MRI scanning can be integrated with continuous hydrological monitoring to reveal emerging flow pathways in rooted soils. These data will inform a mechanistic model that quantifies the effects of preferential flow across different root types and depths, providing new parameterisations for use in rain garden performance models.
How to cite: Geddes-Barton, M., Green, D., Charalampidou, E., Ptashnyk, M., Johnstone, C., and Bush, E.: How does root oriented preferential flow impact rain garden hydrology? , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21335, https://doi.org/10.5194/egusphere-egu26-21335, 2026.
In urban areas, green roofs are increasingly adopted due to their multiple environmental benefits and their ability to mitigate hydro-meteorological risks. Among them, Multilayer Blue–Green Roofs include an additional storage layer that enhances pluvial flood mitigation by retaining excess water that percolates from the soil layer. This storage layer can also be regulated through a valve that allows controlled release of stored water into the urban drainage system. Existing hydrological models for blue–green roofs typically represent processes such as evapotranspiration, leakage and discharge, but the contribution of condensation from the underlying blue layer to soil-moisture dynamics is largely overlooked, despite monitoring evidence showing measurable moisture gains in the substrate associated with concurrent water loss from the storage layer. This study investigates the influence of condensation generated by upward water-vapor fluxes from the storage layer to the soil, assessing the impacts on the soil-moisture dynamics. The conceptual eco-hydrological model proposed by Viola et al. 2017 to simulate the soil-moisture dynamics of traditional green roofs, has been adapted to represents a Multilayer Blue-Green Roof, accounting for the additional storage layers and condensation dynamics. The Multilayer Blue–Green Roof prototype installed in the Engineering Faculty of the University of Cagliari has been selected as case study to calibrate the proposed model. The prototype has been equipped with sensors to continuously measure temperature, soil moisture, water level and discharge. Three years of collected data are available at high resolution for this Multilayer Blue–Green Roof. Rainfall and relative humidity data have been provided by the weather station network of the Regional Environmental Agency (ARPAS – Agenzia Regionale per la Protezione dell’Ambiente Sardegna). Crop coefficient and mass transfer coefficient have been calibrated for each season with the aim to account for the different vegetation cover. Incorporating condensation processes significantly improved model performance, yielding soil-moisture and water-balance simulations closely aligned with observations. Results highlight condensation as a non-negligible process in Multilayer Blue–Green Roofs hydrology and support its inclusion in future roof modelling frameworks.
How to cite: Viola, F., Vakily, S., Cristiano, E., Grosse-Heilmann, M., Corongiu, P., Jakomin, C., and Deidda, R.: The role of condensation from below in soil moisture dynamics within multilayer blue–green roofs, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7069, https://doi.org/10.5194/egusphere-egu26-7069, 2026.
Water scarcity and soil degradation are major constraints for sustainable land management in semiarid regions. This is of particular importance on hillslopes of alluvial environments that are highly susceptible to erosion and carbon losses, both in rural and urban areas. The reuse of treated domestic wastewater for irrigation has emerged as an alternative water source in these regions, and as a sanitation solution; however, its long-term sustainability is often limited by salt accumulation and changes in soil physical and hydraulic functioning under high evaporative demand. This study evaluates the integrated effects of biochar application combined with treated wastewater irrigation on soil carbon stocks, salinity dynamics and hydro-physical properties in a hot semiarid environment.
Field experiments were conducted on shallow, steep sandy loam soils developed on hillslopes of alluvial deposits, characterized by low water storage capacity and strong hydrological connectivity along slopes. Soil surface management strategies included bare soil, organic mulching, and the combined application of mulch and biochar produced from agricultural wood residues, representing contrasting conditions of surface protection and organic input. The system was irrigated using treated domestic effluent with moderate to high electrical conductivity through a localized drip irrigation scheme, reflecting realistic water reuse practices in water-scarce regions. The assessment focused on soil electrical conductivity, total organic carbon and key physical and hydraulic attributes controlling infiltration, water retention and solute transport, monitored over successive field campaigns and soil depths. This integrated approach allowed the evaluation of responses of soil–water–carbon interactions under combined water reuse and soil amendment practices. Results indicate that the integration of biochar with organic surface cover promotes higher soil carbon accumulation and greater temporal stability compared to bare soil conditions. Organic amendments also attenuated salinity buildup under wastewater irrigation, reducing variability in soil electrical conductivity and buffering salt accumulation in the surface layer. These effects are associated with improvements in soil structure and porosity, which enhance water retention and infiltration capacity, reduce surface runoff and limit salt concentration in the root zone, particularly following rainfall events. These processes are especially relevant in sloping alluvial semiarid landscapes, where soil physical degradation and hydrological processes strongly influence carbon redistribution and salinity risks.
Overall, the findings highlight the potential of integrating biochar with treated wastewater irrigation as an innovative and scalable Nature-based Solution strategy for improving soil–water–carbon interactions in semiarid environments. This approach explicitly supports the United Nations Sustainable Development Goals by contributing to SDG 2 (Zero Hunger) through improved soil productivity, SDG 6 (Clean Water and Sanitation) by promoting safe wastewater reuse, SDG 13 (Climate Action) via soil carbon sequestration, and SDG 15 (Life on Land) by mitigating land degradation, while offering practical insights for climate-resilient land use planning and the implementation of Nature-based Solutions in vulnerable dryland regions.
How to cite: Almeida, T., Montenegro, A., Isidoro, J., and Pedroso de Lima, J.: Integrated effects of biochar and treated wastewater applications on soil carbon, salinity and hydro-physical properties in a Semiarid hillslope, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14597, https://doi.org/10.5194/egusphere-egu26-14597, 2026.
Urban runoff frequently carries elevated concentrations of heavy metals such as nickel (Ni), posing significant environmental and public-health risks. Sustainable Urban Drainage Systems (SUDS) offer a promising pathway to mitigate these impacts, particularly through the use of filter media that enhance water decontamination. This study evaluates Filtralite, a lightweight expanded clay aggregate, as a filtration medium for Ni removal, with special emphasis on the evolution of pH under prolonged operational conditions and on the influence of particle size on the material’s treatment capacity.
The research was based on an 80-day experiment designed to simulate an accelerated weathering process similar to what occurs under real operating conditions when SUDS interact with rainfall. Four granulometric fractions (2 mm, 1 mm, 0.5 mm, and 0.25 mm) were tested under controlled, repeated washing cycles carried out statically: the Filtralite was kept submerged in beakers, and its water was replaced on an approximately daily basis throughout the 80-day period. The pH values of the effluent were systematically recorded and interpreted as a proxy for the material’s alkalinity-generating capacity—an essential driver of Ni removal from the contaminated solution.
Results demonstrate a consistent granulometry-dependent pattern in pH evolution. Coarser fractions (2 and 1 mm) experienced a more rapid decline in alkalinity than finer ones: although initial effluent pH values exceeded 10, they dropped below the threshold required for efficient Ni precipitation (≈8.5–9) after only a few litres of cumulative washing. The 2 mm fraction dropped to pH 8–8.5 after approximately 8–10 L of equivalent runoff, suggesting a short effective lifespan in real SUDS applications. The 1 mm fraction exhibited a slower decline, maintaining pH > 9 for a longer period, but ultimately converging toward circumneutral values at extended washing volumes. In contrast, finer fractions (0.5 and 0.25 mm) preserved alkaline conditions throughout most of the experiment. The 0.5 mm material sustained pH values in the range 9–10 for the majority of the test, indicating a more stable and gradual release of alkaline species. The finest fraction (0.25 mm) provided the most robust performance: effluent pH consistently remained between 9.5 and 10 even under high cumulative washing volumes, reflecting the strong buffering capacity associated with its larger specific surface area.
Overall, the findings confirm that Filtralite is an effective and sustainable medium for Ni removal in SUDS, although its long-term performance is highly sensitive to granulometry. Fine fractions provide a prolonged alkaline environment that enhances precipitation-driven removal. These results suggest that finer Filtralite may offer favourable characteristics for potential field applications, supporting more stable and efficient metal removal over extended periods. However, the reduced particle size also implies lower hydraulic conductivity compared to coarser fractions, which could limit infiltration performance in practical implementations. Validation under real operating conditions is therefore still required.
How to cite: Pla, C., Mederos, M., Valdes-Abellán, J., and Benavente, D.: Performance of Filtralite as a filter medium for nickel removal in urban runoff: effects of granulometry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8866, https://doi.org/10.5194/egusphere-egu26-8866, 2026.
Recent climate change has led to increasingly severe short-duration heavy rainfall events, resulting in stormwater volumes that exceed the capacity of existing drainage systems in Seoul. In response, the Seoul Metropolitan Government is planning to construct additional deep stormwater storage and drainage tunnels to mitigate flooding in densely populated urban areas. This study examines effective inflow-control strategies for a planned deep drainage tunnel in the Sadangcheon basin, aiming to reduce urban flooding during extreme rainfall.
The XP-SWMM hydrological and hydraulic modeling software was used to simulate flood scenarios and assess the impact of inflow control on inundation. A flood-analysis model was constructed to reflect current watershed conditions and to simulate one-dimensional sewer flow and two-dimensional surface inundation simultaneously. Using this model, the design inflow to the stormwater storage tunnel and the rainfall duration corresponding to maximum storage utilization were estimated. Optimal inflow-control conditions were derived by adjusting the operating water level of the vertical shaft gate to regulate the inflow initiation time.
Under the fixed water-level control scenario, applying inflow control delayed the time required to reach maximum storage by approximately 20 minutes compared with the uncontrolled inflow condition. The effectiveness of inflow regulation was evaluated through changes in surface inundation area and inundation volume. The results showed a reduction of approximately 34.2% in inundation area and 33.9% in inundation volume. These findings indicate that regulating inflow at the tunnel entrance allows more efficient use of limited storage capacity and helps adjust the time gap between peak flood discharge and the moment when the tunnel reaches full storage. This contributes to the stable operation of deep underground stormwater storage and drainage tunnels during extreme rainfall events.
In addition, variable water-level control conditions were applied to evaluate the tunnel’s operational flexibility under smaller-scale rainfall events. The analysis suggests that adopting adaptive inflow-control strategies can enhance the tunnel’s ability to manage a wider range of hydrologic conditions and improve overall flood-mitigation performance. Based on these results, an efficient operational approach for the planned stormwater storage and drainage tunnel is proposed.
These outcomes collectively demonstrate that inflow-control strategies can significantly improve the performance of deep stormwater storage tunnels by delaying maximum storage time, reducing inundation, and enhancing operational stability during consecutive or extreme rainfall events. The results provide practical guidance for the planning and operation of large-scale urban flood-control infrastructure under changing climate conditions.
Acknowledgements
This work 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 Climate, Energy, Environment(MCEE)(RS-2024-00398012)
How to cite: Lee, D. and Park, J.: A study on inflow control methods for deep stormwater tunnel, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-403, https://doi.org/10.5194/egusphere-egu26-403, 2026.
The complexity of the risks associated with urban stormwater management is increasing world-wide, with climate change and rapid urbanization being among the main drivers. Climate change is intensifying extreme precipitation events to magnitudes that severely challenge the capacity of existing urban drainage infrastructures. Concurrently, rapidly increasing urban density, particularly in developing areas, results in expanded impervious surfaces, thereby raising the surface runoff volumes and peaks. This leads to hazards such as urban flooding, which has become more frequent in recent decades across the globe. Literature shows that integrating Nature-Based Solutions (NBS) with traditional Urban Drainage System (UDS) can improve system performance by providing increased water storage capacity, flood and flow reduction, and other associated benefits. This study employs the Python-integrated Storm Water Management Model (PySWMM) to model and simulate an existing UDS in a rapidly urbanizing catchment in Gurugram City, India. The 42 km² catchment is divided into 21 sub-catchments. A non-stationary/stationary rainfall frequency analysis is applied to account for potential precipitation trends across the analyzed urban area. Similarly, a simplified methodology is adopted for evaluating changes in urbanization using openly available datasets. The functionality of the UDS is assessed for the effects of changes in precipitation and urbanization for the near future, both individually and in combination. The modelled urban water system is intervened with different NBS interventions and their combinations to quantify the effectiveness of NBS in minimizing the impacts of climate change and urbanization. The results demonstrate a significant reduction in flooding and peak surface runoff outflows.
How to cite: Guptha, G. C., Marzadri, A., Swain, S., and Formetta, G.: Stormwater Management for Developing Urban Areas under Precipitation and Urbanization changes: a parsimonious approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17892, https://doi.org/10.5194/egusphere-egu26-17892, 2026.
Traditional riverbank engineering typically involves vegetation removal and channelization measures (e.g., bank hardening and riverbed grading), which simplify the natural flow regime and significantly reduce biodiversity. This study focuses on a mountain stream in Shangshi Village, located in the upper reaches of the Baxi River within the Yong'an City water source protection zone, Fujian Province, China. The area is characterized by excellent water quality and rich aquatic biodiversity, notably the annual summer migration of native fish species. However, flood control interventions involving bank hardening and riverbed grading have homogenized the flow regime, leading to the loss of this migratory behavior. Successful fish migration depends on a combination of hydraulic and geomorphic conditions, including suitable water depth, flow velocity, substrate composition, diverse flow paths, and the presence of specific hydraulic cues. To restore the riverine habitat, this study employs UAV-based aerial photography, hydrological surveys (including discharge, velocity, and depth measurements), and field investigations of streambed composition and riparian vegetation. Integrated with hydrological and hydraulic analyses, a rehabilitation scheme combining riprap structures and vegetative engineering is proposed. The approach aims to reconstruct bank morphology and diversify flow patterns and habitat niches, thereby promoting systematic river ecosystem restoration through nature-based solutions.
How to cite: Chen, J.-C., Fan, J.-Q., Lai, X.-Z., Huang, W.-S., Li, F.-B., and Li, G.-L.: Nature-based Restoration of a Mountain Stream Habitat: A Case Study from Shangshi Village, Fujian, China, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17260, https://doi.org/10.5194/egusphere-egu26-17260, 2026.
The Water-Energy-Food (WEF) Nexus represents a critical framework for sustainable resource management, particularly in water-scarce Mediterranean islands like Naxos, Greece. This research examines the interdependence of water, energy, and food systems on Naxos, a Cycladic island facing challenges from climate variability, tourism pressures, and agricultural demands. We assess the island's natural resources and evaluate current needs for residents and primary production sectors, highlighting inefficiencies in existing infrastructure such as desalination units and energy mixes reliant on fossil fuels. Using geospatial analysis via QGIS, the island was divided into 28 grid cells to quantify rainwater harvesting potential from rooftops, courtyards, and road networks. Annual precipitation data were integrated with land use patterns to estimate harvestable volumes, ranging from 5,800 m³/yr in coastal cells to over 200,000 m³/yr in mountainous areas. Prioritization of water needs focuses on domestic supply for permanent residents and irrigation for crops like potatoes, olives, and vineyards, while incorporating animal manure as a nutrient source to reduce fertilizer dependency and embedded energy costs. Traditional techniques, such as cisterns for rooftop collection and roadside swales/bioretention systems for runoff management, are proposed as low-energy, resilient solutions. Results indicate that optimized harvesting could cover a significant part of irrigation needs and alleviate desalination reliance, enhancing self-sufficiency.
How to cite: Maravelakis, M., Iliopoulou, T., and Sargentis, G.-F.: The Water-Energy-Food Nexus in Naxos Island: Enhancing Self-Sufficiency Through Traditional Techniques, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12878, https://doi.org/10.5194/egusphere-egu26-12878, 2026.
Phytoremediation is an environmentally friendly, cost-effective, and sustainable technology that uses plants to clean up contaminated soil, water, and air. Compared to traditional wastewater treatment methods – which are often energy-intensive and expensive – phytoremediation techniques use low-cost, readily available local materials, have minimal upfront capital investment, are simple to maintain and operate, have little to no energy input, and provide multiple co-benefits (e.g., habitat for wildlife, improvement of local aesthetics, and biomass harvest for composting and biofuel). This study evaluated the effectiveness of a field-scale floating wetland system in reducing concentrations of nutrients and algal toxins (microcystin), using native aquatic plants installed in the equalization basin of a wastewater treatment plant. The floating wetland system was deployed in late spring and, through summer and fall, we monitored nutrient levels, microcystin concentrations, physico-chemical parameters, and plant biomass. A 78% reduction in microcystin was achieved during peak plant growth, and the relative abundance of cyanobacteria decreased from 27.7% to 4.5% during this period. Nutrient assimilation (and plant biomass production) was higher in systems with mixed plants (polyculture), with nutrient reduction reaching peak values of 2968 mg/m2 for NH4+, 1767 mg/m2 for PO43−, and 12 mg/m2 for NOx during the study. Environmental factors such as pH and water temperature also affected nutrient assimilation, with varying effects on both polyculture and monoculture systems. Precipitation was also a key factor influencing microcystin reduction rates, while microcystin toxicity had no significant effect. In order to evaluate the role of microbes in the phytoremediation process, we also performed microbial analysis of wastewater samples and root biofilms, including 16S rRNA gene sequencing. This characterization of the bacterial community revealed significantly higher microbial diversity in the rhizosphere compared to the water. Proteobacteria dominated the rhizosphere (47%–52%) while cyanobacteria dominated the water (30%). The polyculture system had greater abundance of beneficial microbial taxa and metabolic pathways, which was associated with higher plant growth and enhanced nutrient assimilation.
How to cite: Costa Jr, O. and Chen, Z.: Phytoremediation of wastewater using a field-scale floating wetland system, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15239, https://doi.org/10.5194/egusphere-egu26-15239, 2026.
Flood-related damage has increased due to extreme rainfall events driven by climate change. Nature-based solutions are an effective strategy for mitigating flood damage while restoring riverine ecosystems. The objective of this study is to evaluate the effectiveness of nature-based solutions in the Seosi-cheon Stream, South Korea. The study area is a 10.5 km reach downstream from the Guman Reservoir in Gurye-gun. Scenarios for the creation of retention basins were developed, and their effectiveness of flood mitigation and habitat restoration was evaluated. The flood mitigation effectiveness was evaluated using a hydrodynamic model. The InVEST model was used to assess impacts on habitat quality. The site selection of nature-based solutions was discussed in terms of flood mitigation and habitat restoration.
How to cite: Kim, S. K. and Koo, H.: Assessing nature-based solutions for flood mitigation and habitat restoration in the Seosi-cheon Stream, South Korea, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21239, https://doi.org/10.5194/egusphere-egu26-21239, 2026.
Posters virtual: Fri, 8 May, 14:00–18:00 | vPoster spot A
EGU26-8693 | ECS | Posters virtual | VPS11
Is blue-green infrastructure effective in reducing urban flood depth and area?Fri, 08 May, 14:36–14:39 (CEST) vPoster spot A
How to cite: Cheung, P. K.: Is blue-green infrastructure effective in reducing urban flood depth and area?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8693, https://doi.org/10.5194/egusphere-egu26-8693, 2026.
EGU26-18311 | ECS | Posters virtual | VPS11
Laboratory testing and in-situ monitoring of the hydrological response of a resin gravel permeable pavement and a bioswaleFri, 08 May, 14:39–14:42 (CEST) vPoster spot A
The present study investigates the hydrological performance of two Nature Based Solutions (NBS) realised within the urban requalification project of the former military area “Caserma Gavoglio” (now public park), in one of the most heavily urbanized districts of the city of Genoa (Italy). The rapid expansion of urbanization has led to an increase in impervious surfaces and a consequent increase in runoff generation, flood volume and flood peak. Since the required expansion of the stormwater drainage capacity is neither economically nor environmentally sustainable, innovative stormwater management strategies are required. In this context, NBSs represent effective solutions to mitigate runoff generation and peak flows and restore natural infiltration processes.
A resin gravel permeable pavement (PP) was used for the paving of about 40% of the park surfaces while a bioswale was realised alongside the sport field to manage stormwater excess.
The PP was preliminarily tested in the laboratory by monitoring the outflow from a standardized test bed under various rainfall input and slope conditions. The results of the tests were interpreted mathematically using the analogy of the step response function of first- and second-order dynamic systems. This allows to transfer the laboratory results for comparison with field conditions, even if these were not precisely reproduced in the laboratory tests.
Both NBSs were monitored in the field with the objective to measure the outflow rate, representing the inflow to the urban drainage system, and to compare it with the corresponding rainfall input.
Two hydrometric measurement stations and one rain gauge station were installed. Since the stormwater drainage system was already in place, water stage probes were housed inside existing manholes equipped with suitable “V-shaped” weirs. Due to non-standard operational conditions, the measurement stations were preliminarily tested in the laboratory to verify their accuracy prior to field installation.
From the monitored rainfall events, direct comparisons between the measured precipitation and the outflow hydrographs were performed. These analyses enabled the quantification of the retention and detention effects due to the NBSs and their improvement relative to typical impervious paving solutions. The following performance indicators were derived for each significant precipitation event that exceeded the retention capacity of the NBS: (i) the outflow coefficient, defined as the ratio between total outflow and rainfall volumes, (ii) the peak reduction coefficient, i.e. the ratio between peak discharge and peak rainfall intensity and (iii) the system response delay, i.e. the time lag between the centre of mass of the flow hydrograph and that of the rainfall.
Acknowledgements
This work was conducted in the framework of the Urban Nature LABs (UNALAB) project, under the “HORIZON 2020” programme, Smart and sustainable Cities-SCC-02-2016-2017, as a collaboration between the University of Genova (DICCA) and the Municipality of Genova (project partner).
How to cite: Ferro, M., Chinchella, E., Cauteruccio, A., and Lanza, L. G.: Laboratory testing and in-situ monitoring of the hydrological response of a resin gravel permeable pavement and a bioswale, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18311, https://doi.org/10.5194/egusphere-egu26-18311, 2026.
