HS5.14 | Green infrastructure for sustainable urban hazard management
EDI
Green infrastructure for sustainable urban hazard management
Co-organized by NH1
Convener: Daniel GreenECSECS | Co-conveners: Jorge Isidoro, Lei Li
Orals
| Fri, 28 Apr, 08:30–10:15 (CEST)
 
Room 2.15
Posters on site
| Attendance Fri, 28 Apr, 10:45–12:30 (CEST)
 
Hall A
Posters virtual
| Attendance Fri, 28 Apr, 10:45–12:30 (CEST)
 
vHall HS
Orals |
Fri, 08:30
Fri, 10:45
Fri, 10:45
Urban areas are at risk from multiple hazards, including urban flooding, droughts and water shortages, sea level rise, disease spread and issues with food security. Consequently, many urban areas are adapting their approach to hazard management and are applying Green Infrastructure (GI) solutions as part of wider integrated schemes.

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 of GI, Sustainable Drainage Systems (SuDS) or Nature Based Solutions (NBS), 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 GI implementation;

· Laboratory-, field- or GIS-based studies which examine the effectiveness or cost/benefit ratio of GI solutions in relation to their wider ecosystem potential;

· Methods for enhancing, optimising and maximising GI system potential;

· Innovative and integrated approaches or systems for issues including (but not limited to): 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 the opportunities of GI at multiple spatial scales;

· Rethinking urban design and sustainable and resilient recovery following crisis onset;

· Engagement and science communication of GI systems to enhance community resilience.

Orals: Fri, 28 Apr | Room 2.15

Chairpersons: Daniel Green, Elena Cristiano, Jorge Isidoro
08:30–08:35
08:35–08:45
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EGU23-746
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ECS
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On-site presentation
Angana Borah, Raviraj Dave, and Udit Bhatia

Intensified climate extremes in changing climate scenarios with rapid urbanization make urban floods a global concern since the population in the cities is increasing. One way to manage urban floods is the adoption of various adaptation measures. The existing infrastructures for flood adaptation are classified as 'hard,' 'soft,' and 'hybrid' adaptation strategies, which constitute the conventional Stormwater Drainage Network (SWD),  Green Infrastructures (GI) practices, and a combination of soft and hard strategies, respectively. As infrastructures are vulnerable to damage because of exceedance in design life, capacity, or any adverse situation, all adaptation methods are likely to become non-functional in the event of a disaster. Under such circumstances, the flood response of an urban region on account of the non-functionality of both soft and hard adaptation strategies is not well understood. We develop a coupled 1D-2D hydrodynamic model using MIKE+ and generate scenarios to compare the damages in the functional capacity of all three adaptation strategies. We implement this model for Ahmedabad city, India, and our Initial results show the hotspots which are highly prone to urban flooding. Here, we evaluate the hydrodynamic interaction between flood propagation on the surface with components of SWD structures and GI facilities and determine the consequence of their functional damages. Our analysis unfolds all the aspects of utilizing certain adaptation pathways, including the merits and demerits of the success and failure of a project. Our framework could aid in determining the trade-offs between different adaptation pathways from the perspective of building flood-resilient cities. 

How to cite: Borah, A., Dave, R., and Bhatia, U.: Functional response evaluation of hard and soft adaptation strategies in urban flooding, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-746, https://doi.org/10.5194/egusphere-egu23-746, 2023.

08:45–08:55
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EGU23-1711
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On-site presentation
Quantifying the impact of high density deployments of rain gardens on the drainage network
(withdrawn)
Sarah Cotterill
08:55–09:05
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EGU23-2223
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ECS
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On-site presentation
Elena Cristiano, Roberto Deidda, and Francesco Viola

Among the different nature-based solutions proposed for the sustainable development of urban areas, green roofs are becoming more and more popular, thanks to their multiple benefits. Indeed, these nature-based solutions reduce the pluvial flood risk during rainfall events, contribute to the thermal insulation of buildings, mitigate the urban heat island effect, and improve the air quality. The knowledge that citizens have about green roofs, the interest and willingness to pay for their installation are still poorly investigated and quantified, although this meta-information could be a valid support and guidance for policy makers and urban planners. In this work, we investigated, through an anonymous online survey, the perception of people living in Sardinia on the most common urban environmental issues (i.e., urban flood, increase of temperature, energy consumption, air pollution and lack of green spaces), and the willingness to pay for green roof installation on both public and private roofs. We estimated the empirical relation among environmental issues awareness and the willingness to pay for a specific green solution while trying to relate the latter to socio demographic characteristics. Results show that citizens are very interested in having green roofs on public building, and on average they are willing to pay around 35 euro per year for their installation and maintenance. The interest for green roofs on private building is, on the other hand, lower than on public ones, due to the high installation and maintenance costs. Moreover, when possible, citizens would rather have solar panels instead of green roofs, since they fully perceive the economic advantages deriving from the installation and are not fully aware of the green roof benefits.

How to cite: Cristiano, E., Deidda, R., and Viola, F.: Societal interest and willingness to pay for green roofs in Sardinia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2223, https://doi.org/10.5194/egusphere-egu23-2223, 2023.

09:05–09:15
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EGU23-4666
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ECS
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On-site presentation
Snigdha Sarita Mohapatra, Meenakshi Arora, Wenyan Wu, and Manoj Kumar Tiwari

Climate change and population growth have a significant impact on urban water supplies. This is due to the fact that meeting urban water demand with the available water resources is quite challenging due to ever-growing water demand, variable supply as a result of climate uncertainties, and water pollution. In many urban areas around the world, the concept of integrated urban water management (IUWM) has become quite prominent in recent decades to tackle the challenges of urban water supply and management. The main principle of IUWM is to incorporate non-conventional water supply sources, such as stormwater, rooftop rainwater, and recycled wastewater, to augment the water supply and provide fit-for-purpose water. IUWM, if implemented successfully, has the potential to mitigate multiple challenges outlined above including enhanced water security during droughts, reduced waste streams, reduced floods, and enhanced groundwater recharge as well as reduced water pollution.

In this research, an IUWM principles incorporated water balance model (i.e., developed using eWater Source Version 5.4.0.11797) was used to identify the most suitable supply options from multiple water sources to satisfy the water demands under future demand and climate scenarios for the city of Bangalore, India. Five different water supply configurations were generated based on available water sources and within the policy framework to meet water demand. The effect of climate change has been incorporated into the IUWM model configurations through the runoff responses from future precipitation and temperature changes. Future climate change scenarios for four IPCC emission scenarios i.e., ssp126, ssp246, ssp323, and ssp586 have been incorporated from thirteen Coupled Model Intercomparison Project-6 (CMIP6) models (i.e., 0.25° spatial resolution available at the study location). Three water demand scenarios i.e., low (150 liters per capita per day), average (175 liters per capita per day), and high (200 liters per capita per day) for the projected population were considered as per the Indian Standards. The selected configurations were evaluated for water supply reliability (i.e., time and volumetric reliability) in the study area. Further, as multiple future scenarios resulted in multiple water supply reliability solutions under five IUWM model configurations, the robust solution was identified using robustness metrics.

How to cite: Mohapatra, S. S., Arora, M., Wu, W., and Tiwari, M. K.: Integrated urban water management modeling under future water demand and climate scenarios for the city of Bangalore, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4666, https://doi.org/10.5194/egusphere-egu23-4666, 2023.

09:15–09:25
09:25–09:35
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EGU23-4830
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ECS
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Virtual presentation
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MD Rakesur Rahman, Hojun Kim, Doyean Kwon, and Junga Lee

Floods have devastated many urban socio-ecological systems, adding to urban planners' concerns. Floods caused by typhoons and heavy rain are common in South Korea during the summer, and especially Seoul has experienced urban flooding due to unusually localized heavy rains since 2010. According to the Intergovernmental Panel on Climate Change scenarios (IPCC, 2014), flood damage in Korea is expected to increase due to summer-concentrated precipitation. As an example of what happened, record-breaking rainfall in the summer of 2022 caused severe damage in the Gangnam, a prime district in Seoul, Korea, that has been most vulnerable to flood damage due to drainage problems.

Green infrastructure's socio-ecological system aspect has been recognized for its ability to improve the provision of urban ecosystem services and is increasingly being used for stormwater management. Flood resilience necessitates the ability of urban socio-ecological systems to maintain their structures and functions during and after flooding events. In terms of achieving sustainable outcomes for municipalities, green infrastructure has practical limitations, such as a limited capacity for storing and infiltrating stormwater. As an interdisciplinary approach, green infrastructure necessitates the involvement of multiple stakeholders with conflicting interests, and it is critical to identify the best measures to apply in each context for effective flood mitigation strategies. There is, however, a knowledge gap in investigating an urban water system as a social-ecological system that coevolves because of interactions between actors, institutions, and water systems.

Gangnam district has quickly become the focal point for discourses on socio-economic inequality in Korea, consolidating both socio-economic segregation and political conservatism, making social-economic-ecological context critical for any urban planning to be sustainable. The aim of this research is to develop a system for selecting appropriate green infrastructure for resilient urban stormwater management in Seoul's Gangnam district using simulation-based modeling.

The first step will be to identify suitable green infrastructure practices for Gangnam district’s socio-economic context based on a co-benefits analysis, which will include incorporating co-benefits and human well-being into flood management decision-making while taking stakeholders' perceptions into account using a multi-criteria decision support system. The second step involves using the "Green Values Stormwater Management" model (Jaffe et al., 2010) to assess the green infrastructure's ability to adhere to the "4R" principles of resilience: robustness, rapidity, redundancy, and resourcefulness based on simulation results.

The volume of rain captured or retained by the area's green infrastructure, providing feedback on construction and maintenance costs, as well as an estimate of the percentage of the desired volume retention goal being met will be estimated by the simulation model. Additionally, co-benefits such as cost savings and increased real estate value will be calculated and presented. This research framework will assist city planners decide which green infrastructure practices to use for resilient urban flood management.

References

IPCC (2014). Climate Change 2014: Synthesis Report. IPCC, Geneva, Switzerland.

Jaffe, M., Zellner, M., Gonzalez-Meler, M., Cotner, L. A., Massey, D., Ahmed, H., & Elberts, M. (2010). USING GREEN INFRASTRUCTURE TO MANAGE URBAN STORMWATER QUALITY: A Review of Selected Practices and State Programs.

How to cite: Rahman, M. R., Kim, H., Kwon, D., and Lee, J.: A Simulation-based Modeling Approach to Adapt Social-Ecological Green Infrastructure System for Resilient Urban Flood Management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4830, https://doi.org/10.5194/egusphere-egu23-4830, 2023.

09:35–09:45
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EGU23-8630
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ECS
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On-site presentation
Arianna Cauteruccio and Luca G. Lanza

Green roofs are beneficial in urban drainage systems due to their role in mitigating the hydrological response of the largely impervious surfaces to intense rainfall events. Such benefit is often assumed to hold also in case RainWater Harvesting (RWH) is implemented to exploit the collected rainwater for non-potable usages and to save valuable potable water resources. However, the role of green roofs on the RWH efficiency is not obvious and requires detailed investigation by accounting for the local rainfall climatology.   

On the one hand, retention of rainwater operated by the vegetation would reduce the total volume of collected water made available for exploitation. On the other hand, rainwater detention in the green roof substrates would add to the storage capability of the RWH system, therefore improving the delayed supply of water during inter-event dry periods. The resulting efficiency at the annual scale depends on the distribution of precipitation within the year (duration of dry periods, intensity of rain events, frequency of extremes, etc.).

In this work, a behavioural model is developed to investigate the impact of the inflow modulation due to an interposed green roof on the efficiency of a generic RWH system located in the Mediterranean environment (Cauteruccio and Lanza, 2022). Various configurations of both the green roof characteristics (retention and detention performance) and the RWH system (rainwater collection area and storage volume) are compared with the collection from impervious surfaces in terms of non-dimensional reliability indices.

Furthermore, the annual usage volume per unit tank capacity is used as an indicator of the economic benefit associated with the exploitation of the resource, and its variation in case of the various green roof/RWH system design configurations is assessed. In particular, the reduction of the significant overflow ratio that is typical of RWH systems in the Mediterranean climate is calculated, which is interpreted as a positive feature since overflow represents the unused portion of the collected water.

Cauteruccio, A. and L.G. Lanza (2022). Rainwater harvesting for urban landscape irrigation using a soil water depletion algorithm conditional on daily precipitation. Water, 14(21), 3468. https://doi.org/10.3390/w14213468.

How to cite: Cauteruccio, A. and Lanza, L. G.: Competing roles of green roof in rain water harvesting systems: accounting for retention and detention in a behavioural model simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8630, https://doi.org/10.5194/egusphere-egu23-8630, 2023.

09:45–09:55
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EGU23-15672
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ECS
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On-site presentation
Arunima Sarkar Basu and Laurence Gill

Extreme hydro-meteorological events have caused massive devastations in European territories. The rising frequency and severity of hydro-meteorological events such as floods appear to be associated with climate change and land cover change. Flooding can be broadly classified into three types, fluvial flooding, pluvial flooding and coastal flooding. Fluvial flooding occurs when rivers and streams break their banks and water flows out onto the adjacent low-lying areas (the natural floodplains). Many factors are responsible in understanding the impact of rainfall events to fluvial flooding. The factors are size and slope of catchment, permeability of the soil, urbanization and soil compaction, presence of dams upstream to the floodplain and degree to which water can be stored in the dam and the rate of water release.

Pluvial flooding occurs when the amount of precipitation received exceeds the capacity of storm water drainage systems or the capacity of ground to absorb it.

Due to urbanization process, the surface cover of the land alters leading to increasing impervious areas and decreasing infiltration of the soil

The main focus of the research is to understand the effect of willow plantation at a catchment scale for improving pervious areas for flood control. Willow plants have shown high rate of evapotranspiration and improved infiltration. Willow based systems are used to understand the improvement in the rate of evapotranspiration and infiltration in the presence of appropriate climate and representative soil conditions in Ireland.

The willow systems are being monitored in the western, eastern and northern catchments in Ireland which are regulating the evapotranspiration and also the rate of infiltration at a catchment scale. A statistical rainfall runoff model has been deployed to understand the rainfall-runoff relationship. The evapotranspiration has been estimated based on the Penman–Monteith equation, which requires values of mean temperature, wind speed, relative humidity and solar radiation at daily scale. An inter-comparison for rainfall-runoff relationship is made for estimating the percentage change for improvement in runoff in the presence and absence of the willow plantations.

How to cite: Sarkar Basu, A. and Gill, L.: The effect of Nature Based Willow system deployment at a catchment scale for flood control, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15672, https://doi.org/10.5194/egusphere-egu23-15672, 2023.

09:55–10:05
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EGU23-13446
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ECS
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On-site presentation
Karin A. Hoffmann, Rabea Saad, Björn Kluge, and Thomas Nehls

Vertical green is promoted as climate change mitigation and adaptation measure, and it provides green space for the urban population. However, it could be used in urban water management as well if its evapotranspiration, thus its water demand would be predictable.

For optimal performance, plants need to be provided with water, nutrients, and rooting space. But irregular precipitation, drought periods, and lack of natural water storage necessitate additional irrigation preferably by local water sources (such as rainwater runoff and greywater).

The amount of water needed for irrigation can be calculated using the Penman-Monteith approach which quantifies evapotranspiration of vegetated horizontal surfaces. For Vertical Green, the Penman-Monteith equation has already been tested. In that way, water demand of VGS can be calculated for hourly time steps based on radiation, wind speed, and vapor pressure deficit expressed by air temperature and relative humidity data.

The needed meteorological data can be measured on-site or derived, thus adapted – verticalized - from remote climate stations, depending on data availability, and needed accuracy of the results. This study models water demand using (1) on-site measured meteorological data, (2) ‘verticalized’ remote station data, and (3) remote station data. We then compare simulated evapotranspiration with measured lysimetry data for a ground-based Vertical Greenery system of Fallopia baldschuanica monitored in Berlin, Germany.

This study finds radiation and vapor pressure deficit to have the highest impacts on the variance of the results while wind speed has the lowest impact. In this contribution, we present the developed model, verticalization methods for the input parameters and validate the performance of the model based on measured water demands.

How to cite: Hoffmann, K. A., Saad, R., Kluge, B., and Nehls, T.: Modelling reference evapotranspiration for vertical green (in urban areas), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13446, https://doi.org/10.5194/egusphere-egu23-13446, 2023.

10:05–10:15

Posters on site: Fri, 28 Apr, 10:45–12:30 | Hall A

Chairperson: Elena Cristiano
A.78
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EGU23-3381
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ECS
Eleanor Starkey and Edward Rollason

Nature-based Sustainable Drainage Systems (SuDS) have been promoted for enhancing urban drainage, as well as offering additional benefits to urban greening and amenity, and engaging communities in the design and adoption of schemes. However, a lack of data on the efficacy of nature-based options means that schemes often use traditional engineering approaches instead of nature-based designs. Where nature-based options are used, most schemes lack long-term monitoring to understand their effectiveness; interventions are rarely designed to maximise their potential and often underperform once constructed. Existing practices also mean that most schemes are led by technical expertise and hence proceed with token public engagement, and lack support for community acceptance and adoption. This is unsustainable and undermines SuDS as a crucial tool for climate adaptation and sustainable urban development.

The SuDS+ approach argues for a radical rethink of the benefits of SuDS, de-prioritising drainage as their primary driver, and instead conceptualising ‘SuDS+’ as a multi-benefit urban development tool with a range of co-, not additional, benefits. In this approach SuDS become a vehicle for enhancing urban design, amenity, and health and wellbeing which can be adapted to meet community needs and aspirations.

The SuDS+ project, a 5-year Defra funded study in the Northeast of England, aims to develop and deliver community-centred SuDS, embedding innovation in collaborative design, as well as pushing forward new technologies and approaches for nature-based urban water management, and co-developing our understanding of what and how to monitor interventions to develop a robust evidence-base for the future.

This paper outlines the key challenges and how the project will aim to tackle these as a call to reimagine SuDS as a vehicle for delivering greener, healthier, more sustainable, and more resilience urban communities.

How to cite: Starkey, E. and Rollason, E.: SuDS+: establishing a new vision for sustainable drainage in delivering  sustainable and resilient urban communities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3381, https://doi.org/10.5194/egusphere-egu23-3381, 2023.

A.79
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EGU23-4190
Julian Klaus, Paulina Busch, and Michael McHale

Population growth and climate change alter the urban water cycle resulting in increasing frequency and magnitude of urban floods. In this study, we compared stormwater response in an urban drainage system between two adjacent urban sewersheds in Buffalo, NY, USA. At the first site (DEL), comprehensive installations of green infrastructure (GI) (i.e. bioretention cells) were carried out, while the second site (SQ) was minimally influenced by GI practices. Stormflow was monitored as pipeflow at both sites for an observation period of five years, three pre-construction and two post-construction years. We identified storm events and calculated event runoff, as excess flow above baseflow. Additionally, we evaluated annual total flow and peakflow (annual and seasonal) between the sites and between pre- and post-construction. Our analyses were confined to snow-free seasons because storage of precipitation in the snowpack confounds the evaluation of the precipitation-runoff relation. The analysis showed that the GI implementation was highly effective in reducing stormflow. Total annual flow was reduced at DEL between pre- and post-construction, while no trend was observable at the minimally influenced by GI SQ. Also, event-based stormflow was reduced through GI implementation across all snow-free seasons. Last, median event peakflow was clearly reduced through GI, especially in spring and summer, whereas results during fall were less clear. Through this hydrometric analysis, this study is among the first that provided evidence for the efficiency of GI in reducing stormflow beyond the plot-scale and thus provides future guidance on flood mitigation in urban environments.       

How to cite: Klaus, J., Busch, P., and McHale, M.: On the effectiveness of green infrastructure to reduce stormflow at catchment scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4190, https://doi.org/10.5194/egusphere-egu23-4190, 2023.

A.80
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EGU23-8836
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ECS
Livia Serrao, Susanna Ottaviani, Corrado Diamantini, Alessandra Marzadri, Marco Ragazzi, Wilson Alberto Munguita Paulino, Félix Cândido Cláudio Eduardo Macueia, Harold Juvenal Chate, Americo Da Stela Valdimir Msopela, Alfredo Manhota Antonio, and Guido Zolezzi

Urban population has been increasing worldwide in recent decades and it is expected to continue growing in the coming years. Cities are facing the effects of the climate crisis, which primarily impact the most vulnerable contexts, first and foremost informal settlements. In this context, the growth of informal neighborhoods, home to one billion people1, poses complex challenges for the cities of today and tomorrow. In these urban areas traditional, informal and formal social dynamics coexist, strengthened by strong community identities and bonds. Major problems are due to the lack of basic services and infrastructure, making these areas more vulnerable to the increasingly frequent and intense extreme rainfall events. 

In this work, we present the recently launched Europeaid-funded project MUDAR (Mozambique integrated Urban Development by Actions and Relationships), and specifically focus on its component that addresses the dynamics and effects of flooding  in an informal urban area: the Macuti neighborhood in the city of Beira, Mozambique. Macuti is situated on the coast, making it particularly vulnerable to frequent cyclones, one of all Idai, which damaged 49% of its buildings in March 20192. Moreover, it is located on a marshy, purely flat area at the end of an inadequate open drainage network serving the entire city, which is unable to drain the flow at high tide. Macuti, with its almost 17 thousand people (2017), since the early 2000s has been experiencing a rapid growth in spontaneous settlements, which has resulted in a higher population density, with the unbuilt area decreasing by 40% from 2004 to 2022, and soil permeability further reducing in a context where the clayey soil composition already strongly limits rainfall infiltration. These changes, in addition to the inadequate water infrastructure, have exacerbated flooding problems associated with heavy rainfall events (the maximum daily precipitation of the 1990-2020 period was 288.5 mm/day). Investigating the socio-hydrology of flooding in these informal settlements is particularly complex because its requirements for high-resolution topographic, soil, land use and meteorological data, which are very limited in these informal settlements. 

More specifically, we present preliminary outcomes and the proposed project strategy to cope with the intrinsic data scarcity of such context, which is based on carefully designed participatory surveys with local actors. To fill this data gap, a multi-disciplinary approach has been adopted by combining elaborations from satellite image processing (SAR) with in-situ measurements and interviews to inhabitants and professionals. In addition to being involved in providing information about the area, the inhabitants are a crucial actor in the decision-making process for choosing the technical solutions to be implemented. Preliminary results on  flooding dynamics in Macuti neighborhood, as well as on three Nature-Based-Solutions scenarios emerging from the participatory process highlight promising factors that can allow adapting the participatory procedure in similar contexts.

 

1French, M., Trundle, A., Korte, I., Koto, C. (2020). Climate Resilience in Urban Informal Settlements: Towards a Transformative Upgrading Agenda. Climate Resilient Urban Areas, 129-153

2UNOSAT-REACH (2019). Mozambique- Beira City -Macuti - Neighbourhood Damage Assessment- As of 26 March 2019. URL: https://m.reliefweb.int/report/3056948

How to cite: Serrao, L., Ottaviani, S., Diamantini, C., Marzadri, A., Ragazzi, M., Paulino, W. A. M., Macueia, F. C. C. E., Chate, H. J., Msopela, A. D. S. V., Antonio, A. M., and Zolezzi, G.: Engaging local communities in planning Nature-Based-Solutions for urban drainage systems - the MUDAR project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8836, https://doi.org/10.5194/egusphere-egu23-8836, 2023.

A.81
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EGU23-10670
Barbara Minsker and Bardia Heidari Haratmeh

Green infrastructure (GI) has become a common solution to mitigate stormwater-related problems such as water quality and flooding hazards. Despite  widespread acknowledgement of GI benefits, there is a lack of decision support methods that allow practitioners to identify optimal locations and evaluate the costs and benefits of numerous spatially distributed small GI practices at larger scales (subwatershed to entire watershed) under uncertainty. To address these needs, an online Cloud-based interactive tool coupling SWMM (Storm Water Management Model) and the Water Research Foundation LID life cycle model, , called Interactive DEsign and Assessment System for Green Infrastructure (IDEAS_GI), is optimized using a noisy genetic algorithm (GA) with life cycle costs and stormwater volume reduction as the primary objectives. To overcome the computational challenge of probabilistic sampling with the noisy GA and to identify significant features for preferable locations, the GA  is merged with an artificial neural network, which acts as a meta-model (surrogate) for the numerical simulation model (SWMM). Post-optimization, machine learning decision trees are also generated that classify the numerous potential solutions generated by the noisy GA into GI coverage classes based on sub-watershed parameters. This framework is applied to a watershed in Baltimore, Maryland, U.S., under multiple budgetary scenarios. The results suggest that the greatest GI investments under the highest and lowest budgetary scenarios should be allocated to subwatersheds closest to the watershed outlet. For the lowest scenario, GI practices should be installed only in subwatersheds closest to the watershed outlet. When the budgetary scenario is highest, GI is sited across the watershed but highest priority is still given to subwatersheds closest to the watershed outlet. On the other hand, the importance of total distance to the watershed outlet is lower for the medium budgetary scenario. In fact, the impacts of different features for preferable GI coverage for these solutions are more complex, don’t follow a consistent pattern, and require more depth to capture the patterns in their corresponding classifier decision trees. In addition to these GI findings, the results showed that the addition of meta-models decreases average computational time required to reach Pareto frontiers similar to the ones generated by the noisy GA by more than 95%.

How to cite: Minsker, B. and Heidari Haratmeh, B.: Optimization of Green Infrastructure Networks to Maximize Stormwater-Related Benefits and Minimize Life Cycle Costs Using a Noisy Genetic Algorithm and Machine Learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10670, https://doi.org/10.5194/egusphere-egu23-10670, 2023.

A.82
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EGU23-11430
Daniele Masseroni, Majid Niazkar, and Alessio Cislaghi

Infiltration-based green infrastructures (GIs) are commonly constructed to effectively storage the excessive stormwater runoff. These GIs exploit infiltration process, as the key natural phenomenon in the hydrological water balance, to detain excessive stormwater volume, especially at the outlet of the peri-urban watershed. Beside many factors playing significant roles in the performance of the infiltration-based GIs, implementing them in shallow groundwater area still represents a challenge that can restrict their widespread adoption. In fact, the groundwater level, if close to the bottom of infiltration-based GIs, can strongly influence the infiltration process. Basically, the shallow groundwater may theoretically play as a boundary conduction and subsequently reduces the infiltration rate.

The present study investigated the activation of an infiltration-based GI located at the outlet of the combined sewer system in the municipality of Sedriano (12,000 inhabitants in province of Milan, North Italy), monitoring the inflow and the water depth over a period of almost two years. Meantime, groundwater level and meteorological measurements were observed (including precipitation, air temperature, solar radiation, wind velocity, and relative humidity). Using these observations, a Water-Balance Model (WBM) was calibrated on the hydrological response of the infiltration-based GI and then, used to simulate how much time is required to empty under a specific precipitation event, and to understand the spatial distributed performances of these measures under different groundwater levels.

The implementation of an accurate WBM can be a useful tool for designing and assessing the performance of the infiltration-based GIs in shallow groundwater environments in peri-urban areas. This study is an integral part of the project Smart-Green (www.smartgreen.unimi.it) that developed online tools for supporting the water utilities to accelerate the transition towards the sponge cities utilizing GIs techniques.

How to cite: Masseroni, D., Niazkar, M., and Cislaghi, A.: Implementing Water Balance Model for Stormwater Management: the case of an Infiltration-Based Green Infrastructure Under Shallow Groundwater Levels, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11430, https://doi.org/10.5194/egusphere-egu23-11430, 2023.

A.83
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EGU23-13499
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ECS
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Siling Chen, Margaux Antonia Huth, and Andrea Cominola

Green roofs are one of the most widely applied blue-green infrastructure in urban regions to serve several purposes moving towards climate change mitigation and urban adaptation. Their large-scale adoption is critical in enhancing resilience against urban hazards, such as urban flooding, urban heat island effects, and biodiversity loss. Currently, the most popular policy format to encourage their roll-out is subsidy programs. However, the success of such programs is oftentimes evaluated based on siloed governmental data, local evaluation reports, and non-recurrent monitoring campaigns, which may become inconsistent and incomparable across temporal scales and different geographical regions. Due to the lack of open data, complementary metadata, and standard quantitative evaluation tools, monitoring and consistently comparing the effectiveness of different green roof incentivization policies is a challenge in practice. This lack of data and high cost of frequent large-scale monitoring campaigns also hinders city-wide spatial distribution analysis of green roofs and identification of green roof development potential, which could support policymakers in devising effective and sustainable urban management strategies.

Moving towards an automated frequent monitoring of green roof development, 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. In this work, we validate Roofpedia and evaluate its accuracy in automatically identifying and classifying green roofs from satellite images with public ground truth data in Berlin, Germany. Furthermore, we develop a Berlin-based case study where Roofpedia is applied using geospatial data across temporal scales to assess the efficacy of Berlin’s green roofing subsidy program "GründachPLUS", which has provided 2.7 Million Euros of funding for green roof construction since 2019. We first retrieve open-access orthoimagery data, then extract green roof coverages in Berlin across two temporal steps (i.e., before and after subsidy program instigation), and finally evaluate how effectively and promptly the subsidy program fostered the development of green roofs. This study contributes a Machine Learning-based add-on to the current evaluation protocol of the Berlin municipality, which is implemented via threshold-based spectral analysis. We analyze the spatial distribution of green roofs and provide insights into further green roof potentials in the city of Berlin, by identifying interesting hotspots for future green roof development. Upon imagery availability, this automated assessment may be extended to multiple cities to enable comparative studies of various green roofing incentivization policies and offer a transferrable and scalable policy evaluation framework.

How to cite: Chen, S., Huth, M. A., and Cominola, A.: Have roofs in Berlin become greener? Evaluation of Berlin's green roof subsidy program performance using geodata and deep learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13499, https://doi.org/10.5194/egusphere-egu23-13499, 2023.

A.84
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EGU23-13613
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ECS
Giacomo Marrazzo and Anita Raimondi

Urban development leads to an increment of impervious cover that drastically reduces infiltration rates and increases the risk of stormwater floods, also reinforced by the rise of extreme events due to climate change.

In this context, urban trees represent a valid system for sustainable stormwater management. They decrease the runoff discharged in the sewer network and/or in the receiving water bodies.

Trees impact the hydrological cycle through the processes of interception, evapotranspiration and infiltration strictly depending on several factors such as tree features, soils properties, climate, and storm event characteristics.

The objective of the study is to propose an analytical-probabilistic approach to model the contribution of urban trees to the restoration of the water cycle, with particular focus on the evapotranspiration component.

How to cite: Marrazzo, G. and Raimondi, A.: The role of urban trees in water cycle restoration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13613, https://doi.org/10.5194/egusphere-egu23-13613, 2023.

A.85
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EGU23-14713
Adrian Butler, Thomas Rowan, and Athanasios Paschalis

The built environment is being forced to adapt to rising global temperatures and severe weather events such as more intense storms, longer heatwaves etc. The proliferation of impermeable surfaces has over time led to many urban design problems, such as storm surges overwhelming sewers. Increasing urban temperatures are also caused by the built environment, the Urban Heat Island (UHI) effect. These impacts can be tackled through better infrastructure. Permeable paving offers an alternative to many impermeable surfaces, providing a robust surface with the advantage of drainage. Its ability to mitigate heat, however, remains poorly understood.

To address this, a detailed performance evaluation of two permeable paving pads, one a control and the other actively (mains supply) and passively (rainwater retention) watered, was undertaken. The 16 m2 permeable paving pads were installed at Imperial College London’s White City campus (London, UK) and monitored over 4 months (July to October 2021). The pads were bounded by a raised impermeable barrier and consisted of a block layer with foundations of grit underneath. Both pads were placed on a slope enabling them to be drained, a weir prevented flooding and a tap allowed for complete drainage. The pads were instrumented with internal heat and water content sensors, as well as surface thermal sensing, and a dedicated weather station. Several artificial wetting events were conducted during the summer of 2021 alongside controlled laboratory work. A significant cooling effect was found (average of 1, and up to 5 of cooling), which was around half that computed for well-watered green space. It was found that the evaporation rate of the wetted pad was dependent on the degree of saturation, with the greatest heat loss efficiency occurring when the grit layer was partially saturated. A variety of secondary observations were also made, including issues around water fouling, and porous bricks. Whilst permeable paving can assist with flood alleviation, is it hoped, through minor design modifications, that it can also help tackle extreme urban heat impacts.

How to cite: Butler, A., Rowan, T., and Paschalis, A.: Investigation of thermal cooling potential of Permeable Paving at an urban trial site in London, UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14713, https://doi.org/10.5194/egusphere-egu23-14713, 2023.

A.86
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EGU23-16391
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ECS
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Seyed Taha Loghmani Khouzani

Unprecedented famine and rocketing food prices are expected to grow as the emerging shocks continue to reshape our world. Lying at the interface of the resource nexus, the agri-food systems are identified as a primary consumer of global freshwater resources and the main contributor to food security. As a result of external shocks, limitations on human activities have resulted in unexpected disturbances in the global agri-food chain, decreasing the functionality and efficiency of agri-food systems and raising the alarm for a need to transform our food systems. Candidating Peri-urban Green Belts as agents of transformation, this research investigates the potential of adding decentralized and coupled Citizen Science and Nature-Based Sanitation Solutions (CS-NBSS) to cause a transformation in urban and peri-urban contexts. Utilizing existing knowledge from researchers and practitioners in the field, alternative NBSs have been identified which interconnect the WASH sector to the food sector, e.g., evapotranspiration tanks (TEvap). We hypothesize that adding such systems to the existing grey infrastructure can increase food and urban resilience and promote marginalized communities' participation in urban governance. CS and NBS have been prominently highlighted in literature due to their merits in constructing and promoting sustainable attitudes and contexts, causing the underlying systems to behave sustainably. Considering the vital role of governance in steering the technical, economic, social, and environmental dimensions of transformation, a critical question remains on how to go beyond existing public policy research on the participation variable. Current research primarily emphasizes ‘what is (status quo) and what needs to be’ rather than proposing methodological approaches towards the latter. With this objective in mind and focused on the food and WASH sector as primary concerns of peri-urban communities, their local governments, and academia, this project will apply mixed-method research to collaboratively design, implement, monitor, and evaluate CS-NBSS living lab experiences in three case studies, incorporating and assessing the effect of such systems on the participation variable, food, and urban resilience, as well as their potential to cause a transformation.

How to cite: Loghmani Khouzani, S. T.: Peri-Urban Green Belts: Introduction of Decentralized and Coupled Citizen Science and Nature-Based Sanitation Solutions in the Context of Urban Transformation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16391, https://doi.org/10.5194/egusphere-egu23-16391, 2023.

Posters virtual: Fri, 28 Apr, 10:45–12:30 | vHall HS

Chairpersons: Daniel Green, Jorge Isidoro, Lei Li
vHS.9
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EGU23-10523
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ECS
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Husnain Tansar, Huan-Feng Duan, and Ole Mark

Improved understanding of dynamic hydrological performance of green roof (GR) design parameters towards different model responses is important for maximizing its target design goals at the unit-scale. Replication of an optimally designed GR unit at the catchment-scale significantly contributes to achieving its target design goals (i.e., surface runoff reduction, urban flood reduction, peak flow control, etc.). Moreover, adequate efforts are required to explore and provide appropriate knowledge about the categorization of influential and non-influential design parameters with their suitable design spaces to guide researchers, drainage engineers, and stormwater management practitioners for effective and efficient planning, designing and optimization of GR at catchment-scales.

This study employs a robust and comprehensive global sensitivity analysis (GSA) method known as the variogram analysis of response surfaces (VARS) for sensitivity analysis of GR design parameters. Firstly, a total of 13,999 sample points for 14 GR parameters of three layers (i.e., surface, soil and drainage mat) are generated by using the latin hypercube sampling technique and their factor spaces are decided based on design guidelines in current SWMM manuals. Following that, the PySWMM is used to simulate these design samples in a Monte-Carlo-type setting on a conceptual catchment of 0.01km2 (100m2 × 100m2) with 50% treatment area of GR, and the model responses (e.g., surface infiltration, surface outflow, storage volume, and peak flow) are estimated and applied for sensitivity analysis. Finally, VARS evaluates different sensitivity analysis metrics by using different model responses corresponding to their designed samples.

Overall, the senstivity analysis results demonstrate that 8 out of 14 design parameters are highly influential on different model responses, however, the parameters’ sensitivity varies towards different model responses under different perturbation scales and rainfall conditions. Moreover, the selection of an effective range of design space of design parameters is necessary as it has a higher influence on model responses, while the parameters’ rankings and contributions to total sensitivity indices change with the range of design spaces. Furthermore, this research also provides an opportunity through VARS directional variogram index (an integrated sensitivity index) to study and understand the underlying mechanisms of design parameters under different perturbation scales with no extra computational burden. Senstivity analysis results will be presented with insights and recommendations for other regions, which will be helpful for decision-makers for effective planning, designing and implementation of GR. The findings of this parametric study would be helpful for the calibration and optimization of design parameters of GR for different case studies.

 

How to cite: Tansar, H., Duan, H.-F., and Mark, O.: Sensitivity analysis of green roof design parameters in SWMM for its improved understanding of hydrological performance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10523, https://doi.org/10.5194/egusphere-egu23-10523, 2023.

vHS.10
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EGU23-15822
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ECS
Nuria Oliver, Miguel Año, Pura Almenar, Angela Baeza, Carmen Hernández-Crespo, and Miguel Martín

In the face of insufficient water resources and the intensification of extreme events caused by climate change, the generation of non-conventional water sources is an option that should become a priority. Wastewater treated is a water resource that with proper post-treatment can be suitable for maintaining the environmental quality of rivers and wetlands or be used for productive activities such as agricultural uses.

Returning water to the environment in similar conditions to its original state is vital to promote its reuse and to help maintain biodiversity. In this sense, the project Integrating circular economy and biodiversity in sustainable water treatments based on constructed wetlands LIFE RENATURWAT aims to demonstrate that it is possible to obtain high quality water from Waste Water Treatment Plants (WWTP) effluents by combining Nature-Based Solutions (NBS) and industrial wastes.

One of the disruptive issues of this project is exactly the use of a waste generated in the integral water cycle itself, concretely during the production of drinking water, to produce quality water from WWTP. This sludge (DWTS) has inert and non-toxic properties, so usually is disposed in landfills, not taking profit of the economic and environmental benefits derived from its valorisation. Nevertheless, the DWTS has adsorbent capacities due to the coagulant used in the drinking water treatment process.

LIFE RENATURWAT plans to use the DWTS as an active substrate in constructed wetlands (CWs) aimed at upgrading treated urban wastewater. This sludge is dewatered and milled to obtain a grain size similar to sand. The DWTS reinforces the wetland technology so that it can be more efficient and can efficiently remove phosphorus and other pollutants at the same time as generating a habitat in itself.

The solution includes two kinds of CWs operating in series. The first is a vertical subsurface flow constructed wetland with DWTS as a filter medium and the second one is a free water surface constructed wetland. The described system is able to remove phosphorus from wastewater even at very low concentrations, achieving an average total phosphorus concentration in the effluent below than 0.1 mgP/l. This is considerably lower than the legal limit set by Directive 91/271/EEC, UWWTD (1 or 2 mg P/l), as well as the so-called sensitive area 0.6 mg P/l. In this way, a wastewater effluent with a very low phosphorus concentration is obtained, without additional consumption of reagents, addressing one of the main problems faced by WWTP managers, which is the eutrophication of the natural environment and compliance with phosphorus discharge limits. Within the framework of this project, two pilot projects have been implemented, one in the Valencian town of Carrícola, and the other in the Los Monasterios urbanisation (Puçol).

How to cite: Oliver, N., Año, M., Almenar, P., Baeza, A., Hernández-Crespo, C., and Martín, M.: Sludge valorisation to obtain high quality water from WWTP, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15822, https://doi.org/10.5194/egusphere-egu23-15822, 2023.