Sustainable Drainage Systems Research Articles

Drainage Behavior of Sports Pitches–A Case Study Review

The drainage behavior of sports pitches has traditionally been designed from experience with hydraulic performance rarely measured in detail. Within the wider industry and regulatory bodies there is a perception that storm water and increased drainage rates from sports pitches contribute to local flood risk. Empirical observations have suggested that in reality pitch drainage systems may discharge water at low volumes and rates and there is often limited surface run‐off. Furthermore it appears that lack of technical guidance on the discharge of water from sport pitch drainage systems may have led to misunderstanding their drainage behavior and possible benefits they could bring to water management as opposed to perceived dis‐benefits. This paper summarizes selected results of a case study which included field measurements of weather and discharge behavior on a range of natural turf sports pitches in England. The findings from this study indicate that natural turf sports pitches can provide resistance to flow and hence advantageous attenuation of rainfall and storm water. Additionally sports pitches can store large volumes of water within the pervious materials used in their design. The study has confirmed that sport pitches demonstrate the key functions that are reflected in the design requirements of Sustainable Urban Drainage Systems (SuDs) such as pervious pavements providing source control of surface rain water.

Techniques and criteria for sustainable urban stormwater management. The case study of Valdebebas (Madrid, Spain)

Improving the management of the urban water cycle can reduce greenhouse gas emissions and contribute to climate change mitigation in cities. Stormwater in urban areas has traditionally been collected and conveyed to sewage treatment plants, a practice that has continued with the need to manage increased superficial flow. This paper presents the Low Impact Development (LID) measures to improve water management in the new urban development of Valdebebas in Madrid, and the associated benefits. Stormwater was considered a sub cycle; by shortening the water cycle the local use of rainwater was achieved while reducing energy costs and greenhouse gas emissions for off-site treatment.The article analyses the urban water cycle from a preventive approach. It considers how urban design features such as topography and pavement selection were used to convey surface water from impermeable areas to permeable ones (vegetated or permeable pavements) and the infiltration of water into engineered soil, reducing the need for off-site conveyance infrastructure, and the amount of water discharged into municipal treatment installations. Moreover, the captured water increases soil water content available for plants and trees which play an important role in absorbing CO2. Water exceeding soil capacity is collected in the subsurface Sustainable Drainage system (SuDS), including infiltration boxes where water is temporarily stored before moving through the soil toward ground water reserves.This paper describes the approaches and criteria used to design a large scale SuDS infrastructure in the district of Valdebebas, in northeastern Madrid (Spain), and analyses its performance, followed by a comparison with the predictions under three climate change scenarios, which consider not only the variation in peak flows and runoff, but also the reduction in GHG emissions. Additionally, it presents a sensitivity analysis for the main variables in the design of SuDS, and a multicriteria analysis, to compare the different drainage systems.

A study of the application of permeable pavements as a sustainable technique for the mitigation of soil sealing in cities: A case study in the south of Spain

The use of ‘Sustainable Urban Drainage Systems’ (SuDS) has become a more sustainable alternative for managing stormwater, greatly reducing the effects of soil sealing. However, the lack of monitored projects is a barrier to their implementation, as the companies which manage sewer systems cannot quantify the impact and cost-efficiency of SuDS. This paper presents a project developed in the south of Spain, in which the hydrological performance of 3 types of permeable pavements has been analyzed. The efficiencies obtained (over 70%), are higher than or similar to the efficiencies of vegetated SuDS, demonstrating the capacity of these pavements for delaying catchment area response and slow flow velocities, reducing the operating costs of sewer systems and the flood risk, while also ensuring service conditions for cities and safety for pedestrian and vehicular circulation. This pilot site has generated results which are sufficiently consistent so as to be representative, and serve as a reference for other cities with a similar climate.

Increasing vulnerability to floods in new development areas: evidence from Ho Chi Minh City

PurposeFlooding is an emerging problem in Ho Chi Minh City (HCMC), Vietnam, and is fast becoming a major barrier to its ongoing development. While flooding is presently of nuisance value, there is a growing concern that a combination of rapid urban expansion and climate changes will significantly exacerbate the problem. There has been a trend of population being rapidly accommodated in new urban areas, which are considered highly vulnerable to floods, while the development strategy by the local government still attracts more property investments into the three new districts on the right side of Saigon River. This paper aims to discuss the increase in the number of residences vulnerable to flooding, to underline the need for more appropriate future spatial development. For the vision, an application of compact and resilient theories to strategic planning and management of this city is proposed to reduce vulnerability. This paper also highlights the need to better understand growing vulnerability to floods related to urban expansion over low-lying former wetlands and the more important role of planning spatial development accompanied with transportation investment which can contribute to flooding resilience.Design/methodology/approachThis research uses combined-methods geographical information system (GIS) analysis based on secondary data of flood records, population distributions, property development (with the details of 270 housing projects compiled as part of this research) and flooding simulation. This allows an integrated approach to the theories of urban resilience and compactness to discuss the implication of spatial planning and management in relevance to flooding vulnerability.FindingsThe flooding situation in HCMC is an evidence of inappropriate urban expansion leading to increase in flooding vulnerability. Although climate change impacts are obvious, the rapid population growth and associated accommodation development are believed to be the key cause which has not been solved. It was found that the three new emerging districts (District 2, 9 and ThuDuc) are highly vulnerable to floods, but the local government still implements the plan for attracted investments in housing without an integrated flooding management. This is also in line with the development pattern of many coastal cities in Southeast Asia, as economic development can be seen as a driving factor.Research limitations/implicationsThe data of property development are diversified from different sources which have been compiled by this research from the basic map of housing investments from a governmental body, the Department of Construction. The number of projects was limited to 270 per over 500 projects, but this still sufficiently supports the evidence of increasing accommodation in new development districts.Practical implicationsHCMC needs neater strategies for planning and management of spatial development to minimize the areas vulnerable to floods: creating more compact spaces in the central areas (Zone 1) protected by the current flooding management system, and offering more resilient spaces for new development areas (Zone 2), by improving the resilience of transportation system. Nevertheless, a similar combination of compact spaces and resilient spaces in emerging districts could also be incorporated into the existing developments, and sustainable drainage systems or underground water storage in buildings could also be included in the design to compensate for the former wetlands lost.Social implicationsThis paper highlights the need to better understand growing vulnerability to floods related to urban expansion over low-lying former wetlands and emphasizes the more important role of planning spatial development accompanied with transportation investment which can contribute to flooding resilience. Coastal cities in southeast countries need to utilize the former-land, whereas feasibility of new land for urban expansion needs to be thoroughly considered under risk of natural disasters.Originality/valueA combination of compact spaces with improved urban resilience is an alternative approach to decrease the flooding risk beyond that of traditional resistant systems and underlines the increasingly important role of urban planning and management to combat the future impacts of floods.

Characterization of wash-off from urban impervious surfaces and SuDS design criteria for source control under semi-arid conditions

Knowledge about pollutant wash-off from urban impervious surfaces is a key feature for developing effective management strategies. Accordingly, further information is required about urban areas under semi-arid climate conditions at the sub-catchment scale. This is important for designing source control systems for pollution. In this study, a characterization of pollutant wash-off has been performed over sixteen months, at the sub-catchment scale for urban roads as impervious surfaces. The study was conducted in Valencia, Spain, a city with a Mediterranean climate. The results show high event mean concentrations for suspended solids (98mg/l), organic matter (142mgCOD/l, 25mgBOD5/l), nutrients (3.7mgTN/l, 0.4mgTP/l), and metals (0.23, 0.32, 0.62 and 0.17mg/l for Cu, Ni, Pb, and Zn, respectively). The results of the runoff characterization highlight the need to control this pollution at its source, separately from wastewater because of their different characteristics. The wash-off, defined in terms of mobilized mass (g/m2) fits well with both process-based and statistical models, with the runoff volume and rainfall depth being the main explanatory variables. Based on these results and using information collected from hydrographs and pollutographs, an approach for sizing sustainable urban drainage systems (SuDS), focusing on water quality and quantity variables, has been proposed. By setting a concentration-based target (TSS discharged to receiving waters <35mg/l), the results indicate that for a SuDS type detention basin (DB), an off-line configuration performs better than an on-line configuration. The resulting design criterion, expressed as SuDS volume per unit catchment area, assuming a DB type SuDS, varies between 7 and 10l/m2.

Sustainable Drainage in Challenging Environments

AbstractThe provision of Water, Sanitation and Health (WASH) is recognised by the UN as a human right. However, drainage is not. The lack of drainage leads to flooding and can impact on quality of life and human health. This is particularly true in the most vulnerable of populations who live in informal settlements, favelas and refugee camps. This paper shows the potential of sustainable drainage systems or SuDS to address issues of excess surface water and lack of greywater management in these challenging of environments. SuDS mimic nature by encouraging infiltration, storage and slow conveyance of water to attenuate the storm peak, reduce flooding, improve water quality and provide opportunities for amenity and biodiversity. A layer of complexity is added when considering disease vectors such as mosquitoes which may be prevalent in these environments. By encouraging water underground and reducing puddling of water between dwellings and on the street, their breeding sites are reduced, providing a means of reducing their impacts on health due to zika, dengue or chikungunya. Due to the lack of governance, land tenure and any form of planning, residents of informal settlements and favelas need to be actively engaged in improving the quality of their surroundings. Refugee camps, on the other hand, are formally set up by the UNHCR with WASH installed, thus there is potential to influence policy, to encourage installation of drainage at the same time as WASH so that WASH becomes WASH'D, possibly a first step in recognising drainage as a human right.

Evaluating the longer term benefits of sustainable drainage

Sustainable drainage systems (SuDS) can bring a wide range of benefits in addition to reductions in flood risk. However, there is limited quantified evidence of the value of these benefits. To help address this, the Construction Industry Research and Information Association led a project to develop the Benefits of SuDS Tool (Best). The approach presented in this paper shows how scenario planning can be used in Best to evaluate longer term benefits in the face of future uncertainty. Three case studies are presented, showing how this can inform robust decisions and the selection of SuDS options for maximum value.

Effectiveness of ABC Waters Design Features for Runoff Quantity Control in Urban Singapore

Active, Beautiful, Clean Waters (ABC Waters) design features—natural systems consisting of plants and soil that detain and treat rainwater runoff—comprise a major part of Sustainable urban Drainage Systems (SuDS) in Singapore. Although it is generally accepted that ABC Waters design features are able to detain runoff and reduce peak flow, their effectiveness in doing so has not been studied or documented locally. This research aims to determine their effectiveness in reducing peak flow based on a newly constructed pilot precinct named Waterway Ridges. Four types of ABC Waters features have been integrated holistically within the development, and designed innovatively to allow the precinct to achieve an effective C-value of 0.55 for the 10-year design storm; the precinct-wide integration and implemented design with the aim of substantially reducing peak flow are firsts in Singapore. The study is based on results from an uncalibrated 1D hydraulic model developed using the Storm Water Management Model (SWMM). Identification of key design elements and performance enhancement of the features via optimisation were also studied. Results show that the features are effective in reducing peak flow for the 10-year design storm, by 33%, and allowed the precinct to achieve an effective C-value of 0.60.

Enhancing future resilience in urban drainage system: Green versus grey infrastructure

In recent years, the concept transition from fail-safe to safe-to-fail makes the application of resilience analysis popular in urban drainage systems (UDSs) with various implications and quantifications. However, most existing definitions of UDSs resilience are confined to the severity of flooding, while uncertainties from climate change and urbanization are not considered. In this research, we take into account the functional variety, topological complexity, and disturbance randomness of UDSs and define a new formula of resilience based on three parts of system severity, i.e. social severity affected by urban flooding, environmental severity caused by sewer overflow, and technological severity considering the safe operation of downstream facilities. A case study in Kunming, China is designed to compare the effect of green and grey infrastructure strategies on the enhancement of system resilience together with their costs. Different system configurations with green roofs, permeable pavement and storage tanks are compared by scenario analysis with full consideration of future uncertainties induced by urbanization and climate change. The research contributes to the development of sustainability assessment of urban drainage system with consideration of the resilience of green and grey infrastructure under future change. Finding the response measures with high adaptation across a variety of future scenarios is crucial to establish sustainable urban drainage system in a long term.

Independent Validation of the SWMM Green Roof Module

Green roofs are a popular Sustainable Drainage Systems (SuDS) technology. They provide multiple benefits, amongst which the retention of rainfall and detention of runoff are of particular interest to stormwater engineers. The hydrological performance of green roofs has been represented in various models, including the Storm Water Management Model (SWMM). The latest version of SWMM includes a new LID green roof module, which makes it possible to model the hydrological performance of a green roof by directly defining the physical parameters of a green roof’s three layers. However, to date, no study has validated the capability of this module for representing the hydrological performance of an extensive green roof in response to actual rainfall events. In this study, data from a previously-monitored extensive green roof test bed has been utilised to validate the SWMM green roof module for both long-term (173 events over a year) and short-term (per-event) simulations. With only 0.357% difference between measured and modelled annual retention, the uncalibrated model provided good estimates of total annual retention, but the modelled runoff depths deviated significantly from the measured data at certain times (particularly during summer) in the year. Retention results improved (with the difference between modelled and measured annual retention decreasing to 0.169% and the Nash-Sutcliffe Model Efficiency (NSME) coefficient for per-event rainfall depth reaching 0.948) when reductions in actual evapotranspiration due to reduced substrate moisture availability during prolonged dry conditions were used to provide revised estimates of monthly ET. However, this aspect of the model’s performance is ultimately limited by the failure to account for the influence of substrate moisture on actual ET rates. With significant differences existing between measured and simulated runoff and NSME coefficients of below 0.5, the uncalibrated model failed to provide reasonable predictions of the green roof’s detention performance, although this was significantly improved through calibration. To precisely model the hydrological behaviour of an extensive green roof with a plastic board drainage layer, some of the modelling structures in SWMM green roof module require further refinement.

Investigation into the long-term stormwater pollution removal efficiency of bioretention systems.

In recent years, there has been a steady increase in the number of bioretention systems installed worldwide. However, there has only been limited research on the long-term effectiveness of these sustainable urban drainage system devices. This paper presents the results of a series of controlled field experiments investigating the pollutant removal efficiency of three, 10-year-old, bio-filtration systems that have been in service in the Sunshine Coast in Australia. The results of this study suggest that the long-term pollution removal performance of these systems may not be as effective as previously thought and further research is needed.

A framework to support decision making in the selection of sustainable drainage system design alternatives

This paper presents a new framework for decision making in sustainable drainage system (SuDS) scheme design. It integrates resilience, hydraulic performance, pollution control, rainwater usage, energy analysis, greenhouse gas (GHG) emissions and costs, and has 12 indicators. The multi-criteria analysis methods of entropy weight and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) were selected to support SuDS scheme selection. The effectiveness of the framework is demonstrated with a SuDS case in China. Indicators used include flood volume, flood duration, a hydraulic performance indicator, cost and resilience. Resilience is an important design consideration, and it supports scheme selection in the case study. The proposed framework will help a decision maker to choose an appropriate design scheme for implementation without subjectivity.

Contamination of Detained Sediment in Sustainable Urban Drainage Systems

Adsorption is a key water pollution remediation measure used to achieve stormwater quality improvement in Sustainable urban Drainage Systems (SuDS). The level of contamination of detained sediment within SuDS assets is not well documented, with published investigations limited to specific contaminant occurrence in ponds, wetlands or infiltration devices (bioretention cells) and generally focused on solute or suspended sediment. Guidance on contamination threshold levels and potential deposited sediment contamination information is not included in current UK SuDS design or maintenance guidance, primarily due to a lack of evidence and understanding. There is a need to understand possible deposited sediment contamination levels in SuDS, specifically in relation to sediment removal maintenance activities and potential impact on receiving waterways of conveyed sediment. Thus, the objective of the research presented herein was to identify what major elements and trace metals were observable in (the investigated) SuDS assets detained sediment, the concentration of these major elements and trace metals and whether they met/surpassed ecotoxicity or contaminated land thresholds. The research presented here provides evidence of investigated SuDS sediment major element and trace metal levels to help inform guidance and maintenance needs, and presents a new methodology to identify the general cause (anthropocentric land use) and extent of detained SuDS fine urban sediment contamination through use of a contamination matrix.

The potential of green infrastructure application in urban runoff control for land use planning: A preliminary evaluation from a southern Italy case study

Among the approaches for run-off regulation, green infrastructure is identified as non-traditional measure to compensate the effects of soil sealing generated from urban development. It is recognized as a way to increase the provision of urban ecosystem services and is increasingly being used in research and practice on storm-water management through Sustainable Urban Drainage Systems (SUDS). The adoption of SUDS in urban planning might protect hydrological and ecological dimensions of landscapes while providing resilient options to face flood risk management.This paper shows the assessment of SUDS potential to increase the regulating service capacity in a dense urban catchment in southern Italy. A comparison between scenarios of pre-implementation and post-implementation of SUDS is performed through catchment simulations with a hydraulic model. Results showed different effectiveness of SUDS options, in terms of variations of the indicator chosen as proxy of the regulating service capacity. Results showed a better performance obtained by green roofs than permeable pavements, highlighting a limited capacity of run-off regulation achieved with SUDS deployment in public areas only. This suggests that innovative policies to encourage private land owners to adopt measures of SUDS could be fundamental for the retrofitting of urban settlements.

SuDS for managing surface water in Diepsloot informal settlement, Johannesburg, South Africa

Sustainable drainage systems (SuDS) imitate natural water management processes in catchments that have been degraded due to urbanisation. The aim is to reduce the quantity of stormwater runoff and improve water quality. Management of rainwater in the informal settlement of Diepsloot in Johannesburg is compounded by domestic wastewater discharged into the informal lanes. These lanes fall outside the mandate of the City of Johannesburg’s stormwater management system; hence residents need to rely on their own initiatives to address surface-water problems. This preliminary study investigated the introduction of SuDS to enhance existing surface-water interventions, as a low-cost flexible approach. Using action research methods, small-scale interventions were designed, constructed and refined by residents and researchers at two sites close to the Jukskei River. While the primary intention of the research was to reduce standing water in the public areas, water quality testing indicates that the SuDS reduced some pollutants. Nitrate and phosphate concentrations were slightly lowered through the introduction of permeable channels and soakaways, while these interventions had a moderate effect on chemical oxygen demand. The involvement of residents at the two sites was markedly different, reflecting divergent priorities and social dynamics. Spontaneous continuation of the SuDS system at one of the sites indicates successful knowledge and skills exchange. This study was of limited duration with only two sets of water quality tests; therefore, longer term monitoring is strongly advised to be able to give more robust assessment of this type of intervention.Keywords: SuDS, action research, water quality, informal settlements, Diepsloot

Assessing surface water flood risk and management strategies under future climate change: Insights from an Agent-Based Model

Climate change and increasing urbanization are projected to result in an increase in surface water flooding and consequential damages in the future. In this paper, we present insights from a novel Agent Based Model (ABM), applied to a London case study of surface water flood risk, designed to assess the interplay between different adaptation options; how risk reduction could be achieved by homeowners and government; and the role of flood insurance and the new flood insurance pool, Flood Re, in the context of climate change. The analysis highlights that while combined investment in property-level flood protection and sustainable urban drainage systems reduce surface water flood risk, the benefits can be outweighed by continued development in high risk areas and the effects of climate change. In our simulations, Flood Re is beneficial in its function to provide affordable insurance, even under climate change. However, the scheme does face increasing financial pressure due to rising surface water flood damages. If the intended transition to risk-based pricing is to take place then a determined and coordinated strategy will be needed to manage flood risk, which utilises insurance incentives, limits new development, and supports resilience measures. Our modelling approach and findings are highly relevant for the ongoing regulatory and political approval process for Flood Re as well as for wider discussions on the potential of insurance schemes to incentivise flood risk management and climate adaptation in the UK and internationally.

Applicability of sustainable urban drainage systems: an evaluation by multi-criteria analysis

Urban flooding has become more serious and worldwide in recent years, especially in the big cities of developing countries. This study uses a multi-criteria analysis (MCA) approach to evaluate the applicability of sustainable urban drainage systems (SUDS), a flood control measure, in the central part of Ho Chi Minh City, Vietnam. The output of the personal computer storm water management model along with interviews with 140 households was used to assess the efficacy and acceptability of four SUDS alternatives: rainwater harvesting, green roof, urban green space and pervious pavement. On technical performance, green roof was the best alternative, followed by pervious pavement, urban green space and rainwater harvesting. Results of the social survey, however, diverged largely from the results of the technical assessments. In particular, people generally prefer public SUDS such as urban green space and pervious pavements to household solutions. With respect to the MCA, we applied four different procedures: Borda count, pair-wise voting, range of value and analytic hierarchy process. Despite some differences, the integrated results from MCA largely agree that urban green space is the most favourable type of SUDS, followed by green roof, pervious pavement and rainwater harvesting.

Sustainable Pervious Concrete Incorporating Palm Oil Fuel Ash as Cement Replacement

Pervious concrete is one of the best materials used in sustainable drainage system to control the stormwater at source. The use of waste materials in concrete is able to reduce the negative impacts of concrete towards the environment. Therefore, this study presents the development of a sustainable pervious concrete by partially replacing cement with palm oil fuel ash (POFA) from palm oil industry. Properties, including void content, compressive and tensile strength as well as permeability were discussed. The results indicated that it is possible to produce sustainable pervious concrete by incorporating POFA. Furthermore, pervious concrete containing POFA showed higher water permeability and void content but lower compressive and tensile strength than control pervious concrete. However, the obtained compressive and tensile strength were within the acceptable range which is reported for strengths of pervious concrete.

Wet season hydrological performance of green roofs using native species under Mediterranean climate

Urban areas generate considerable amounts of stormwater runoff due to a high percentage of impervious surfaces. In Mediterranean climates, during winter, large volumes of rainfall over short periods of time can cause flooding. Green roofs are emerging as a tool for stormwater management under the Sustainable Urban Drainage Systems philosophy. This paper investigates the influence of rainfall patterns and types of native vegetation cover upon the rainfall-runoff relations of a green roof under a Mediterranean climate during the autumn/winter period. Test beds were installed on a rooftop in Lisbon, Portugal, incorporating a substrate layer 150mm deep, three native vegetation covers and one non-vegetated control. Rainfall and runoff data were monitored over a 6-month autumn/winter period. Results show that the vegetated systems reduced the stormwater runoff, attenuated peak flow and delayed runoff. Overall, 69 of 184 events did not produce runoff, median retention ranged from 55 to 100% and median peak attenuation from 97 to 100%. The combination of shrubs, grasses and mosses proved to be the most effective vegetation cover. Antecedent substrate moisture and plant rainfall interception significantly influenced green roof stormwater performance for all the vegetation covers. Estimations based on the experimental green roof data, an empirical model and a detailed spatial analysis, revealed that, by greening 75% of the flat roof area of the municipality of Lisbon, approximately 166 500–224 000m3 of water could be retained, relieving the drainage systems and preventing floods.

Assessing the impact of swales on receiving water quality

Swales are one type of sustainable drainage system (SuDS) which contribute to the management of water quality in receiving waterbodies. Using a semi-quantitative approach, an impact assessment procedure is applied to the residual water quality that is carried forward to surface waters and groundwaters following treatment within a swale. Both volumetric and pollutant distributions are considered as stormwater passes through the swale system. The pollutant pathways followed by TSS, nitrate, chloride, metals (Cd, Cu, Pb, Zn) and polyaromatic hydrocarbons (PAHs) are determined for a swale receiving highway runoff. For TSS, metals and PAHs between 20% and 29% of the total mean influent pollutant load is predicted to be directed to infiltration through the underlying soils compared to between 4% and 16% of chloride and nitrate. Although surface water impacts are deemed possible, the discharges of swales to groundwaters are assessed to represent a negligible impact for effectively maintained systems.