Sustainable Drainage Systems Research Articles

Influence of sediment characteristics on long-term hydrology and water quality behaviour during the clogging process of a permeable asphalt

Sustainable urban drainage systems (SUDS) are common solution to address flow discharges, runoff volumes and pollutant concentrations caused by urban expansion and climate change trend. Among them, permeable pavements (PP) effectively manage and treat stormwater. The clogging process of PP has been addressed in previous studies but there is still room for improvement the knowledge about how it affects to their performance in terms of hydrological behaviour and pollutant removal and how it depends on sediment properties. The present study simulates and analyses the behaviour of a permeable asphalt through 47 sediment loading steps tested for six different sediment classes under laboratory conditions. The experiments were performed using permeable asphalt slabs in two laboratory rainfall simulators, measuring reductions in permeability, filtered and runoff flows, and water quality variations in effluents according to sediment loads and rainfall events. The results showed significant reductions of permeability (22–99 %) for sediment surface loads from 1 kg/m2 onwards, except for very fine sediments (<125 μm) (1 %). Permeability recovery after vacuum cleaning varied between 8 % and 100 % of original permeability. Sediment particle size distribution, organic matter content and rain events sequence were key variables influencing the permeability loss and its recovery, and quality of filtrated water. The hydraulic efficiency was high, filtrating almost 100 % of the applied rainfall, whenever the sediment surface load was below 4 kg/m2, above which surface runoff was produced. The efficiency of the slab for pollutant retention was 96 % for COD, 76 % for TN, 79 % for TP, and 98 % for TSS.

Evaluation of bioswale efficiency in consideration of climate and design features: A case study in Hong Kong

Sustainable drainage systems (SuDSs) have been increasingly implemented to mitigate the stress of urbanisation, climate change, and water scarcity. However, SuDS construction in densely populated metropolitan cities with a subtropical monsoon climate such as that of Hong Kong may encounter challenging field conditions and site constraints. This fieldscale study aimed to verify the performance of bioswale for flood resilience and water quality improvement under various simulated rainfall scenarios with different intermittency and intensity. In the six simulated rainfall events, the results showed that metal removal and flow attenuation were excellent under minor and moderate rainfall events, while the system performance was compromised during intensive rainfall events. The removal of turbidity and nutrients from the runoff was moderate owing to the low contaminant levels in the synthetic stormwater. The dry state of soil media led to more fluctuating results for water quality control. To further enhance the treatment capability under practical site constraints, the addition of appropriate soil amendments and the integrated use of different SuDS measures are recommended in order to achieve sustainable development goals and resilient water management.

Evaluation of bioswale efficiency in consideration of climate and design features: A case study in Hong Kong

Sustainable drainage systems (SuDSs) have been increasingly implemented to mitigate the stress of urbanisation, climate change, and water scarcity. However, SuDS construction in densely populated metropolitan cities with a subtropical monsoon climate such as that of Hong Kong may encounter challenging field conditions and site constraints. This fieldscale study aimed to verify the performance of bioswale for flood resilience and water quality improvement under various simulated rainfall scenarios with different intermittency and intensity. In the six simulated rainfall events, the results showed that metal removal and flow attenuation were excellent under minor and moderate rainfall events, while the system performance was compromised during intensive rainfall events. The removal of turbidity and nutrients from the runoff was moderate owing to the low contaminant levels in the synthetic stormwater. The dry state of soil media led to more fluctuating results for water quality control. To further enhance the treatment capability under practical site constraints, the addition of appropriate soil amendments and the integrated use of different SuDS measures are recommended in order to achieve sustainable development goals and resilient water management.

Unmanaged vegetated roofs hydrological performance in subtropical areas: An investigation in São Paulo, Brazil

Extensive vegetated roofs are Nature-based Solution with the ability to manage rainwater runoff in densely built spaces. Despite the large amount of research demonstrating its water management abilities, its performance is poorly quantified under subtropical climates and when using unmanaged vegetation. The present work aims at characterizing the runoff retention and detention of vegetated roofs under the climate of São Paulo, Brazil, accepting the growth of spontaneous species. By using real scale prototypes under natural rain, a vegetated roof hydrological performance was compared with a ceramic tiled roof. By using models with different substrate depths under artificial rain, changes in the hydrological performance were monitored for different antecedent soil moisture contents. Results from the prototypes showed that the (i) extensive roof attenuated from 30 % up to 100 % the peak rainfall runoff; (ii) delayed the peak runoff from 14 up to 37 min and (iii) retained from 34 % up to 100 % the total rainfall. Furthermore, results from the testbeds indicated that (iv) when comparing two rainfalls with same depths, the one with longer duration can saturate more the vegetated roof and thus undermine more its ability to retain water; and (v) when not managing the vegetation, the vegetated roof's soil moisture content loses correlation with the substrate depth, as plants will also develop more and will more effectively restore the substrate retention capacity. Conclusions point to extensive vegetated roofs as a relevant sustainable drainage system in subtropical areas, but demonstrate that its performance is highly dependent on structural factors, weather factors and level of maintenance. Such findings are expected to be useful for practitioners dimensioning these roofs as well as for policy makers towards a more accurate standardization of vegetated roofs in subtropical regions and Latin American developing countries.

Building flood-resilient cities by promoting SUDS adoption: A multi-sector analysis of barriers and benefits in Bogotá, Colombia

In light of rapid urbanization and climate change, managing urban flood risk by combining traditional pipe-bound infrastructure with sustainable urban drainage systems (SUDS) has recently gained significant attention. SUDS provide a wide range of social, economic, and environmental advantages; nonetheless, there are perceptions, barriers, and benefits whose understanding is lacking, especially in the context of developing countries. To fill these gaps, a case study was conducted in the city of Bogotá, Colombia's capital city, systematically investigating the visions of four key actors, i.e., the public sector, urban developers, a private non-profit organization, and community members of a flood-prone area. Thematic analysis supported by an inductive–deductive coding approach was employed to analyze data collected from in-depth semi-structured interviews and questionnaires. After identifying and categorizing 39 barriers in Bogotá, technical and institutional/organizational barriers such as “operation and maintenance” and “unclear institutional responsibilities” prevailed over financial ones. The assessment of benefits yielded a total of 34 results and demonstrated the wide scope of SUDS strategies, ranging from “use of harvested water in secondary uses” to “promotion of environmental awareness” and “corporate image enhancement.” Furthermore, there are direct relationships between barriers, benefits, and actors, strengthened by particular objectives, motivations, and needs. The findings of this study highlight the significance of interdisciplinary approaches to achieve comprehensive sustainable urban water planning and improved flood risk management. Further work on benefits quantification and participatory spatial-hydraulic modeling could foster SUDS interest, broadening the debate beyond the technical realm.

Floods and Adaptation to Climate Change in Tourist Areas: Management Experiences on the Coast of the Province of Alicante (Spain)

One of the principal challenges for cities on the Mediterranean coast is the management of urban runoff after episodes of intense rainfall. This problem is aggravated by the effects of climate change, with the increase in the frequency and intensity of extreme weather phenomena in this region. In light of this situation, the local governments, in collaboration with the concessionaire companies providing supply and sewage services, are committed to adopting measures aimed at a more efficient management of non-conventional water resources. Examples of good practice for reducing urban flood risk and adapting to climate change are those actions developed in the tourist municipalities of Alicante, Torrevieja, and Benidorm, where measures have been implemented or have been planned and integrated with green spaces, with a commitment to sustainability, such as sustainable urban drainage systems (SUDS) or Nature-Based Solutions (NBSs). This study analyses these case studies, based on a detailed review of the technical projects that contemplate each of the actions. Furthermore, several field trips were made with technical personnel who are familiar with the measures adopted. The results show that the implementation of these systems contributes to advancing the reduction of urban flood risk and the adaptation to climate change, creating more resilient and safer urban spaces for the citizens residing in them.

Evaluation of a Modular Filter Concept to Reduce Microplastics and Other Solids from Urban Stormwater Runoff

This paper describes an innovative Decentralized Technical Sustainable Drainage System (SuDS) concept, which is based on technical devices, such as sieves, sedimentation barriers, floating barriers and a magnetic module, which addresses, mainly, the fine matter. The SuDS is designed as a retrofit system so that no costly and time-consuming conversion measures are necessary. Due to the possibility of free configurability of individual modules in the three levels, road, gully and drain, a novel solution approach is presented, which is not available on the market, for a reduction in solids in general and microplastics in particular. The retention performance of selected modules and their combinations is demonstrated by means of bench tests according to the test procedure of the German Institute for Construction Engineering (DIBt) for the evaluation of decentralized treatment systems. Four different rain intensities, from light to medium up to heavy rain, are charged to the filter modules. Collected and fractionated road-deposited sediment (RDS) was selected as the test substance (10 kg). Additional tests with tyre powder, PE pellets, cigarette butts and candy wrappers helped to make clear the filter process of the particulate matter. The retention performance was determined by the mass balance between the defined dosage and at the outlet. For this purpose, the total volume flow of the effluent was passed over a stainless-steel sieve with a diameter of 600 mm and a mesh size of 20 µm. For the test substance, RDS retention rates up to 97% were measured. Very fine matter, particularly, was technically challenging to obtain; &lt;63 µm up to 66% could be retained by the filter modules. Modules in the road space, such as porous asphalt or additional retention spaces, in the area of the curb as well as direct infiltration in the road drainage shaft are theoretically described and discussed. The outlook also addresses the potential of an intelligent network to reduce the input of pollution from urban stormwater runoff.

Assessment of the thermal properties for the geothermal use of a permeable pavement structure for pedestrian and cycle paths

Sustainable Drainage Systems (SuDS) have positioned themselves as one of the most widely applied Green Infrastructure (GI) techniques for sustainable stormwater management. In recent decades, new lines of research have emerged leading to the geothermal use of SuDS. The aim is to optimise available space in cities and minimise dependence on non-renewable energy sources. Previous research has focused on determining the feasibility of combining the two technologies, both in laboratory and field studies. Other aspects such as the influence of the surface geothermal system on the quality of the water present in the SuDS were also studied. This previous research has focused mainly on permeable pavements, positioning them as one of the SuDS techniques of reference in this line of research. This article attempts to give continuity to what has been established by other authors. It studies in depth the thermal properties of a complete section of permeable pavement under different hydraulic operating conditions. To this end, a complete section of a permeable pavement has been simulated in the laboratory using Hot-Box tests as set out in different international standards. With these tests, the values of thermal transmittance and equivalent thermal conductivity were determined. The aim of this research is to establish a test procedure for the thermal properties of permeable floorings, based on standardised equipment. The aim is to better understand the heat transfer procedures inside SuDS. In this way, it will be possible to optimise the design of these in combination with surface geothermal elements.

Flood Management with SUDS: A Simulation–Optimization Framework

Urbanization and climate change are the main driving force in the development of sustainable strategies for managing water in cities, such as sustainable urban drainage systems (SUDS). Previous studies have identified the necessity to develop decision-making tools for SUDS in order to adequately implement these structures. This study proposes a simulation–optimization methodology that aims to ease the decision-making process when selecting and placing SUDS, with the specific goal of managing urban flooding. The methodology was applied to a real case study in Dresden, Germany. The most relevant variables when selecting SUDS were the spatial distribution of floods and the land uses in the catchment. Furthermore, the rainfall characteristics played an important role when selecting the different SUDS configurations. After the optimal SUDS configurations were determined, flood maps were developed, identifying the high potential that SUDS have for reducing flood volumes and depth, but showing them to be quite limited in reducing the flooded areas. The final section of the study proposes a combined frequency map of SUDS implementation, which is suggested for use as a final guide for the present study. The study successfully implemented a novel methodology that included land-use patterns and flood indicators to select SUDS in a real case study.

The importance of permeability in modelling soil-atmosphere interaction

Soil-atmosphere interaction has been attracting increasing interest as the seasonal variation of pore water pressures (pwp) has been linked to a variety of geotechnical problems (e.g. slope stability and serviceability, foundation subsidence or swelling, desiccation cracking etc.) or has been identified as part of the solution of geotechnical problems (e.g. in sustainable urban drainage systems). Prediction of how the pwp will change within soils of low permeability under the combined effect of evapotranspiration and precipitation requires adequate knowledge of the soil permeability and how it varies spatially (e.g with depth) and temporally (e.g. with suction or degree of saturation, void ratio or due to the opening and closing of desiccation cracks). Nonetheless, in-situ measurements of permeability that satisfy both the spatial and temporal variation are difficult. In order to clarify the importance of variable permeability in predicting pwp variations under atmospheric loads, a series of one- and two-dimensional finite element analyses was performed, where the permeability model and the variation of permeability were parametrically studied. The results demonstrated that the variation of permeability, as well as the model employed in the analysis, e.g. allowing or not for desiccation cracking, influenced the values of suction calculated as well as the pwp profile with depth, highlighting the importance of estimating the spatial and temporal variation of permeability with some level of confidence.

Calculation of release time of water in soil layer

This article discusses the importance and principles of drainage system design in irrigated land. Weather and the type of cultivated crop are analyzed as the main factors for the drainage system. Also, since there is no single empirical formula for determining the duration of groundwater discharge through ditches for designing efficient and sustainable drainage systems in areas where water-saving irrigation technologies are introduced, a certain new method for determining this time is presented as a recommendation.

Technology prospection for sustainable drainage systems as a means to propose changes in the Master Plan of the Municipality of Frutal, Minas Gerais

RESUMO Sistemas de drenagem urbana sustentáveis (SUDS) são tecnologias que dispensam as tradicionais galerias pluviais e têm como premissa a sustentabilidade. Frutal, município do estado de Minas Gerais, sofre com problemas de drenagem pluvial e está em processo de atualização de seu plano diretor. O objetivo do trabalho é discutir, em termos teóricos, a aplicação dos SUDS nesse município, apresentando sugestões para seu plano diretor, bem como realizar a prospecção de tecnologias SUDS para fundamentar futuros estudos técnicos acerca da aplicação dessas tecnologias em Frutal, contribuindo com a literatura sobre SUDS. Para tanto, adotou como procedimentos metodológicos o estudo de caso, a revisão de literatura e o mapeamento de patentes. Como resultados, o trabalho identificou os pontos críticos de inundações e processos erosivos em Frutal, enfatizando os problemas de inundação nos bairros Centro, XV de Novembro, Princesa Isabel, Jardim das Laranjeiras, Progresso, Novo Horizonte e Caju, e de processos erosivos nos bairros Ipê Amarelo e Waldemar Marchi. Expôs uma série de diretrizes sobre os SUDS que poderão nortear eventuais mudanças no plano diretor e futuros projetos legislativos e técnicos, como incentivos econômicos e campanhas de conscientização acerca dessa tecnologia, e fornece exemplos de tecnologias patenteadas que poderão ser referência para posteriores ações de drenagem urbana, especialmente do tipo pavimentos permeáveis, sobretudo para áreas com elevado índice de ocupação do solo e com dificuldades para instalação de equipamentos superficiais de drenagem.

Malls Mire Community Woodland: restoring biodiversity on a brownfield site, a green infrastructure project in Glasgow, Scotland

Malls Mire Local Nature Reserve, Glasgow’s first community woodland, is an interesting case study of a project that is aiming to impact all the pillars of sustainability, especially environmental protection and social equity through a community-led approach. Situated within the Toryglen area in the south of the city, the site has a varied history of agriculture, forestry, golf, and industrial development. It also has a legacy of associated pollution and dumping of waste materials. Urban Roots, the charity involved in the management of the site, has worked alongside Clyde Gateway and Glasgow City Council on a green infrastructure project. Funded through the European Regional Development Fund Green Infrastructure programme, administered through NatureScot, with additional resources from Sustrans, it has enabled large scale improvements at Malls Mire. The work which began in 2020 has connected greenspaces throughout Malls Mire, brought derelict land into positive management and also saw new Sustainable Drainage Systems ponds installed on site. The wide range of resulting benefits include improved access, increased personal safety, shared-use paths, better lighting, opportunities for outdoor recreation, education and volunteering as well as enhanced habitats and benefits for biodiversity and climate change adaptation.

Application of Sustainable Drainage System as a Model of Flood Control with Environmental Insight in Medan City

Application of Sustainable Drainage System as a Model of Flood Control with Environmental Insight in Medan City

Preliminary identification of areas suitable for Sustainable Drainage Systems and Managed Aquifer Recharge to mitigate stormwater flooding phenomena in Rome (Italy)

This paper proposes a preliminary and large-scale survey methodology to identify areas suitable for indepth analysis for the application of Sustainable Drainage Systems and Managed Aquifer Recharge. These techniques are frequently applied to increase the natural infiltration capacity of water into the ground and their effectiveness depends on the local hydrogeological and morphological characteristics. The study area is the city of Rome where the aim is to mitigate the problems related to rainwater which, in case of extreme events, struggles to infiltrate into the ground, overloads the undersized drainage systems, and floods the urban space.The proposed method involves GIS geospatial analysis of the permeability of outcropping lithologies, the digital elevation model, and the piezometric levels of the aquifers. To identify the suitable zones, areas characterised by high permeability and a piezometric level that would confer a volumetric capacity to possibly store even large quantities of water, without triggering possible problems of water table rise, were identified. Data were divided into classes and indexed to compare and overlap them. Furthermore, the final result was compared with the urban flooding phenomena and the soil permeability map of Rome. The results of the performed analysis show that the preliminary suitable conditions to apply SuDS and MAR in Rome are widespread. The geological setting of the city is characterised by permeable lithologies in many places with an effective infiltration potential that would allow rainwater to infiltrate the subsoil and reach the first available aquifer.

Pathogens in Runoff Water Treated by a Sustainable Urban Drainage System in a Developing Country

Sustainable Urban Drainage Systems (SUDS) are commonly used to control flooding in urban areas. These structures store and treat stormwater runoff. Several studies in high-income countries have reported the presence of pathogens in runoff water, but it is expected that runoff water in developing countries contains higher pathogen concentrations given their lack of resources to properly manage sewage; this could result in higher risks of infection for people interacting with SUDS. In this study, we investigated pathogen concentrations (i.e., Salmonella spp. and E. Coli O157) at the micropool of a SUDS train composed of a grassed swale followed by a dry extended detention basin in Bogotá (Colombia) during a 25-week period. We also estimated the risk of infection with the analyzed pathogens, given the high level of exposure to the detention structure. Additionally, we investigated if any of the physicochemical or meteorological variables were associated with pathogen concentrations at the site. We found that pathogen concentrations greatly exceeded concentrations reported for stormwater runoff in developed countries, namely 1562 CFU/mL, on average, for Salmonella spp. and 9160 CFU/mL, on average, for E. Coli O157. The risk of infection from Salmonella spp. and E. Coli O157 greatly exceeded risks previously reported for recreational waters and SUDS. Pathogen concentrations were associated with precipitation and the concentration of suspended solids in the runoff. Given our findings, it is recommended that SUDS in developing countries should consider potential higher pathogen concentrations in stormwater runoff to reduce exposure.

Probabilistic modeling of sustainable urban drainage systems

Sustainable Urban Drainage Systems (SUDS) include strategies and solutions for distributed stormwater management and control. They are strongly encouraged, especially in highly urbanized areas that suffer the combined effect of impervious surfaces and the increase in extreme rainfall events due to urbanization growth and climate change. Their integration into traditional urban drainage systems can mitigate flood risk and pollution of receiving water bodies. The main goal of SUDS is to restore the natural water balance by increasing infiltration and evapotranspiration processes and promoting rainwater harvesting and reuse. This paper proposes an analytical-probabilistic approach for SUDS modeling applicable to different systems. Developed equations allow estimating the runoff and residual storage probability for evaluating the efficiency of the storage volume both in terms of flood control and, depending on SUDS type, in terms of emptying time or water needs supply. The modeling considers the possibility of consecutive chained rainfalls; this feature is relevant for SUDS, often characterized by low outflow rates. Relating characteristic parameters to a probabilistic level (the Average Return Interval, ARI) makes the formulas interesting to be used in the design practice. An application to two case studies confirmed the goodness of the proposed method.

Sustainable Stormwater Management at Urban Expansion Areas of Potential Significant Flood Risk

The Preliminary Flood Risk Assessment (PFRA) for the Greek territory, according to European Directive 2007/60/EC, was completed in 2012 and was revised in 2019. Areas of Potential Significant Flood Risk (APSFR) were defined (and revised) for each River Basin District (RBD). Meanwhile, in 2018, the Flood Risk Management Plans (FRMPs) were approved - by Greek Authorities - for each RBD. In the FRMPs specific measures are proposed for the funding of Stormwater Management (SM) projects that will be designed according to the principles of Sustainable Development (SD), i.e., Best Management Practices (BMPs), Green Infrastructure (GI), Low Impact Development (LID), Urban Natural Water Retention Measures (NWRM) and Sustainable Drainage Systems (SuDS). Within this framework, a preliminary study is drawn up in order to specify some innovative proposals for Sustainable Stormwater Management (SSM) in three areas located into the APSFR of RBD ‘EL11’ (Eastern Macedonia), located in Northern Greece. Two of these areas, Perigiali and Nea Peramos are coastal, while the third one, Doxato, is a continental, plain area. Urban expansion plans are approved for all three cases. The study proposes the implementation of an Innovative Stormwater Management Plan (ISMP) for each area.

Optimal Positioning of RTC Actuators and SuDS for Sewer Overflow Mitigation in Urban Drainage Systems

Real-time control (RTC) and sustainable drainage systems (SuDS) can be implemented simultaneously to enhance the performance of existing urban drainage systems (UDS). However, significant challenges arise when choosing the optimal locations due to hydraulic interactions between the different interventions and the high number of possible configurations. This paper presents a novel optimization–simulation framework to optimize the spatial allocation of flow control devices (FCDs) combined with SuDS for combined sewer overflow (CSO) spill mitigation within UDS. Optimal intervention schemes were identified by a genetic algorithm (GA), combining different numbers of FCDs installed in existing manholes with simplified SuDS implemented in different portions of the catchment. The methodology was tested on two case-study catchments with different characteristics to mitigate CSO spills during synthetic storm events. FCD-SuDS configurations were then validated during continuous rainfall series, resulting in CSO spill volumes reduction ranging between 11% and 45% compared to the baseline networks. The results demonstrate how the GA-based method can efficiently identify optimal placement schemes within UDS characterized by different distributions of in-pipe storage potential as well as hydrological responses to rainfall-runoff events, enhancing the combined benefits of the two decentralized solutions for mitigating CSO spills.

Continuous Quantity and Quality Modeling for Assessing the Effect of SUDS: Application on a Conceptual Urban Drainage Basin

The development of computational tools based on urban drainage models is fundamental for the correct selection of SUDS. The present study proposes a systematic approach based on continuous modeling on USEPA SWMM. The objective was to select the most suitable Sustainable Urban Drainage Systems (SUDS) by evaluating several aspects related to their design and configuration. The proposed methodology was applied to a conceptual watershed with meteorological information from Santander, Spain. The analysis of SUDS design parameters showed that only the surface variables showed a sensitivity of ≈20% for berm height and vegetation volume. The optimal configuration for the case study was a SUDS train consisting of green roofs, permeable pavements, vegetated swales and rain gardens, with 1% of the total subcatchment area cover, one structure, and a semi-aggregated spatial distribution. The methodology proved efficient but also highly dependent on the case study parameters and the meteorological conditions. The SUDS proved to have different efficiencies (30%—90%) in reducing the total runoff volume, the peak flow, and the pollutant loads depending on the region where the conceptual watershed was modeled. The methodology proved to be efficient for studying the combinations and interconnection of seven different typologies, as well as the effect of SUDS configuration, design and distribution on their performance.