Tuesday Poster Session - Catchment perspective

Climate change, characterised by longer periods of drought and urban overheating, intensifies the pressure on urban water resources and underscores the importance of alternative water sources. In-sewer captured streams could be a valuable water source, but uncertainties remain regarding their microbiological water quality and the resulting legal usability. Furthermore, the influence of analytical methods on water quality assessments is unclear. This study, therefore, examines the microbiological water quality of urban streams, which are integrated into the sewer system, using established faecal indicator-based methods (E. Coli and Enterococci) and innovative microbial source tracking. From the analysis results, the legal usability of the urban streams was derived for three use cases: “irrigation of urban greenery”, “irrigation in urban gardening”, and “utilisation for artificial streams”, and it was analysed whether the faecal contamination is due to recent human contamination. The analyses show that the legal limits for E. Coli and Enterococci in the urban streams are exceeded in all three use cases, despite microbial source tracking revealing no evidence of human contamination. The results suggest that existing assessment methods and legislation require adaptation to scientific advances in order to integrate alternative water resources more sustainably into urban water management strategies and meet the requirements of resource-efficient urban water management. 

The springs in Seine-Saint-Denis were once valued as a key resource for the population. Over the 19th and 20th centuries, radical changes in land use resulted in their almost complete disappearance from the urban landscape and from people's memories. However, in a context of resource scarcity and climate change, unconventional waters such as spring water represent an opportunity for local authorities to develop new water-efficient facilities and cultural initiatives based on a heritage-led approach. Accordingly, the research center Cerema carried out a study for the département of Seine-Saint-Denis aimed at identifying springs and ways to make better use of springs. The study focused on the springs of the Oligocene hills and plateaus, the old hydraulic networks that captured them, and the discharge of clear water into the sewerage systems. The survey methodology was based on interviews with local stakeholders, on a combination and comparison of historical, geological, topographical and sanitation data, and on field research. A map of water points for each plateau was then produced. In total, around ten former aqueducts and more than 60 springs and fountains were identified. Finally, the study lists urban facilities that use spring water within the département, which could inspire new ones. 

Dijon Metropole launched a comprehensive study in 2021 on stormwater management in order to develop an integrated territorial policy that reconciles repaving, greening of urban spaces, and the reuse of stormwater. This initiative is part of the metropolitan strategy for water conservation and food transition, transforming runoff water into a local resource for urban agriculture. As part of this study, hydrological modelling was carried out at the scale of 275 stormwater outlets from separate sewer systems to estimate the volumes of runoff that could potentially be harvested for agricultural use. Based on cadastral, hydraulic, and meteorological data (the wet year 2018 and the dry year 2022), the method combines Geographic Information Systems (GIS), soil impermeability rates, and seasonal climate adjustment to assess the actual runoff at the outlet. This presentation highlights the innovative approach of Dijon Metropole, as well as the cross-disciplinary nature of stormwater management, positioned at the intersection of sanitation challenges, climate change adaptation, and the territory’s food policy. 

Green infrastructure (GI) is increasingly promoted as a flexible approach for mitigating urban flooding and improving water quality, yet its design and evaluation often rely on highly simplified or inconsistent parameter choices. This study develops an integrated framework that combines parameterization, sensitivity analysis, uncertainty assessment, and cost-effectiveness evaluation to provide a more transparent basis for GI planning in data limited cities. A database derived from published studies was used to establish representative parameter ranges for bio-retention cells, green roofs, and permeable pavements. The Sobol analysis revealed that only a few parameters dominate hydrological and water quality responses, indicating that model behaviour is governed by a concentrated set of controls rather than the full parameter space. These influential parameters were then distributed through the model to quantify performance uncertainty across a set of climate scenarios, producing output distributions that reflect the variability inherent in GI systems. The cost-effectiveness assessment further shows that some configurations can offer stable hydrological benefits relative to their life cycle cost, even when rainfall intensifies under future scenarios. The framework therefore provides a practical path for evaluating GI strategies in regions where observed data are limited, and it highlights the need to incorporate parameter uncertainty when assessing long-term stormwater resilience. The approach is generalizable and can support the design of robust and economically viable interventions in rapidly growing urban environments. 

Extreme weather events phenomena such as heat waves, cold surges, droughts, and heavy rainfall, are intensifying globally and in South Korea, creating significant stress for urban green infrastructure (UGI). This study developed a multi-method extreme weather exposure index for permeable pavements and green roofs using bias-corrected CMIP6 projections (2015--2100) and six key indicators (TXx, TNn, HWD, CWD, CDD, Rx1day/R20mm). Indicator weights were derived using Analytical Hierarchy Process (AHP), Principal Component Analysis (PCA), and entropy methods, revealing consistent dominance of heat and drought under AHP/PCA (ρ = 0.74--0.93) and higher influence of cold extremes under entropy. Despite methodological differences, all indices identified the cities Daegu, Gwangju, and Seoul as high-exposure cities. The framework provides actionable, scenario-based exposure scores that support climate-adaptive UGI design, prioritization of vulnerable cities, and long-term resilience planning. 

Use of simulation model technology for stormwater runoff projects is considered as standard approach in civil engineering practice. However, simulation models are subjected to many uncertainties associated with the complex environment to be modelled. Model results are biased and do not provide accurate information necessary for optimal long-term investment into water infrastructure. It is challenge for urban modelling specialists to reduce the level of uncertainty associated with distinct modelled processes. The paper focusses on uncertainties associated with hydrological modelling of stormwater runoff into drainage network. Frequently used in urban engineering domain “Time-Area” modelling method (based on Thiessen polygons) is argued to provide underestimated results especially for heavy rainfalls with high intensities. Authors aim on quantification of this uncertainty and suggest alternative method (TAMod) to improve level of surface runoff modelling results. 

Urban development and widespread impervious surfaces have significantly altered natural water balances, exacerbating challenges such as groundwater depletion, urban overheating, and flooding. To address this, new guidelines prioritize restoring natural water cycles through reduced runoff and increased evapotranspiration. This study presents a large-scale water balance model for the city of Innsbruck using SWMM-UrbanEVA, incorporating detailed Blue-Green Infrastructure (BGI) data. The model utilizes high-resolution aerial imagery and climate data to classify land use and simulate the long-term water balance across 173 districts. Initial results indicate that while evapotranspiration dominates the water balance (73-74%), the model currently underestimates runoff compared to validated sewer models. Cross-validation with a detailed district model attributes this discrepancy to an overestimation of disconnected areas in the underlying survey data. Future work will focus on integrating shading factors and calibrating the model against established conceptual sewer models. 

Bogotá faces frequent wildfires, urban floods, waterlogging and landslides—hazards intensified by climatic variability and rapid urban expansion. This study integrates more than 80,000 hydrometeorological incidents reported through Bogotá’s official risk and climate-information system, along with historical records from 81 meteorological stations operated by IDEAM, the national authority in hydrology and meteorology (Instituto de Hidrología, Meteorología y Estudios Ambientales), and IDIGER, the agency leading the District Risk Management System. Retrospective matrices of up to 60 antecedent days were constructed, and Extreme Gradient Boosting (XGBoost) models were trained to identify optimal windows capable of reproducing historical dynamics and generating future scenarios. Windows of 14, 21 and 16 days produced robust performance for wildfires, flooding and landslides, with metrics consistent with official records. Historical reanalysis and SSP-based projections reveal spatial variability and differential increases in future hazard probabilities. Comparison with the current distribution of SUDS highlights a structural mismatch between existing infrastructure and areas of highest projected vulnerability. These findings underscore the need to integrate predictive models, climate scenarios and nature-based solutions into urban planning and risk-management protocols to strengthen resilience and climate adaptation in Bogotá. 

Previous research has shown rainwater harvesting can be used to meet non-potable demands, remove pollutants from stormwater runoff, and mitigate peak flow rates and runoff volumes without requiring a large footprint. Studies have also shown that rainwater harvesting is the most effective at managing stormwater runoff when the tank has sufficient storage available between storm events. Storage may become available through human intervention (e.g., irrigation) and/or through a passive or active release mechanism. However, passive release systems can contribute to runoff during storms, and active release systems typically consist of proprietary components that can be expensive to obtain. We are currently monitoring the hydrologic performance (e.g., bypass) of an active release system comprised of readily available controllers and sensors retrofitting a 7,949 L cistern compared to a passive release system retrofitting a 7,949 L tank in Georgetown, South Carolina, USA. Monitoring began in September 2025 and will continue through September 2026. Preliminary data indicate the passive release system has captured 92% of the runoff generated from a 97 m2 roof and slowly drained 74,838 L of captured runoff. The active release system has captured 73% of the runoff from a 97 m2 roof and slowly drained 57,023 L of captured runoff. 

As rainfall events intensify, adaptive stormwater management systems are essential to reduce flood risks and alleviate peak flows. This project presents StormPack, a real-time control (RTC) system designed to optimize stormwater pond performance through automated outlet operations. Built on the open-source hardware and software framework developed by the University of Michigan, StormPack integrates rainfall forecasts with real-time hydrologic data to preemptively drain ponds before storms arrive, reducing the likelihood of flooding and erosive flows. Designed as an open-source system, it emphasizes accessibility and scalability through comprehensive documentation and low-cost components. This approach will lower barriers to adoption for municipalities, researchers, and community organizations while enabling customization for multiple stormwater control measure applications. This presentation will cover barriers to adoption for open-source design, early deployment insights, and open-source documentation. It will highlight how integrating forecast data with RTC provides a cost-effective, adaptive solution for stormwater management and aids decision-making for improved municipal operations. 

Urban drainage systems are transitioning from isolated sewer networks to integrated urban water systems due to climate change, urban growth, and increasing water-quality requirements. This work analyses the hydraulic interaction between the drainage network and surface-water system in Eindhoven, showing that river levels influence flooding patterns, CSO performance and inflow to the wastewater treatment plant. Based on this analysis, a methodology is proposed to identify opportunities for integrated real-time control (RTC) during this transition. Hydraulic modelling in EPA-SWMM is used to represent both subsystems and evaluate how changes in water levels alter the direction and timing of exchange. The results highlight that river inflows via CSO weir events reflect existing connectivity and define locations where coordinated operation can be applied. In this context, RTC can support integrated management by actively managing storage and discharge pathways across subsystems. The approach aims to enable adaptive use of existing infrastructure and inform future water management planning in Eindhoven.