Chapter 34 Drainage design

Despite being widely implemented, sustainable urban drainage systems (SUDS) do not always function flawlessly. While SUDS have been tested extensively and seem to perform well on a laboratory or pilot scale, practitioners' experience is different: failures in SUDS occur regularly in practice, resulting in malfunctioning systems, water nuisance and high costs. To anticipate their malfunctioning, and thus to improve their performance, a better understanding of failures occurring in SUDS and their underlying causes is needed. Based on an explorative case-study approach, consisting of site visits and semi-structured interviews with urban water professionals, this study presents an inventory of technical failures in SUDS and an analysis of their root causes. In total, 70 cases in 11 Dutch municipalities have been documented. The results show that the interfaces between SUDS and other urban systems are prominent failure locations. In addition, we found that failures originate from the entire development process of SUDS, i.e., from the design, construction and user/maintenance phase. With respect to the causes underlying these failures, our results show that these are mainly socio-institutional in nature. These are valuable insights for both practitioners and scholars, contributing to a renewed socio-technical urban water system with more sustainable water management practices.

How can we make sustainable urban drainage systems (SUDS) smart? SUDS help us to manage surface water runoff from urban environments but they are capable of delivering much more. This paper looks beyond the water quantity and quality improvement functions of SUDS and investigates the multiple benefits that can be gained by implementing smart SUDS solutions. This work provides a new perspective, using methodologies not normally associated with SUDS research, to determine multiple benefits. The outputs of the work can potentially assist decision-makers, designer and planners in recognising the potential for multiple benefits that can be delivered by SUDS. The ecosystem services (ES) associated with a large redevelopment in Dundee, Scotland, UK, are identified and a public perception study together with public participatory geographical information system (PPGIS) methods was used to confirm the goods and benefits of the SUDS. The paper presents findings on the public perception of SUDS as they provide cultural benefits such as recreation, aesthetics and biodiversity. The results show that greenspace is important when choosing a location, and willingness to pay for greenspace is high in this area. This paper concludes that SUDS provide multi-functional benefits in relation to the ES, thereby justifying the cachet of being termed Smart SUDS.

The drainage system in the Kedungmundu Road area has several channels that can no longer accommodate the rainwater discharge, resulting in runoff of rainwater in the drainage channel, which causes flooding and puddles of rainwater in the Kedungmundu Road Area. Drainage in the Kedungmundu Road area has problems such as silting channels due to garbage, soil sedimentation, and insufficient channel dimensions. In the hydrological analysis, the rainfall intensity is 129,586 mm/hour. As the hydraulic analysis, the drainage channel is normalised by dredging sediment in the channel. If there is still rainwater runoff, additional channel dimensions are carried out, taking into account the existing conditions that only Karanggawang Lama road, H. Abdurochman road, and Kedungmundu Lama road changed. Channel dimensions, while for other channels, it is not possible to change the channel dimensions for that, it is necessary to apply SUDS. The Sustainable Urban Drainage System, or in SWMM 5.1 called Low Impact Development, is carried out using rainwater harvesting (Rain Barrel) and Permeable Pavement. The recapitulation of the application of the LID concept in the planning area is known to cover an area of 8.3 hectares of the total planning area of 54.48 hectares. This LID concept can reduce the total runoff value in each sub-catchment, thereby reducing the amount of rainwater discharge that enters the drainage channel with a percentage decrease in the average total runoff value of 19%. The Budget Plan needed to rehabilitate canals and dredging sediments and implement the Sustainable Urban Drainage System (SUDS) is around IDR 5,405,300,000.

In the past years, alternative drainage approaches have emerged, such as Sustainable Urban Drainage Systems (SUDS), to prevent run-off and flooding impacts on the most vulnerable zones of the cities. These systems not only provide the benefit of water regulation but also promote other types of ecosystem services. Several studies have developed optimization tools to assist SUDS selection, location, and design. However, they do not consider a comprehensive set of ecosystem services (e.g., provision, regulation, cultural, and support services). This research proposes a flexible and adaptable methodology to incorporate SUDS in different stages of urban projects using a multi-objective optimization technique to minimize run-off, maximize ecosystem services and minimize cost. The methodology comprises four phases: (1) the preliminary analysis of ecosystem services potentially generated by each SUDS type, (2) the priority and opportunity index quantification, (3) the physical feasibility analysis, and (4) the multi-objective optimization tool implementation. The methodology was successfully applied to three different urban areas of Bogotá city (Colombia). Results evidence that the interaction of the budget constraints and the available area restrict the potential benefits of SUDS implementation. These results are helpful to support different urban planning stages.

Many urban water quality and flooding problems may potentially be addressed by disconnecting stormwater from the formal drainage system and installing source control sustainable drainage systems (SuDS) instead. This approach is referred to as SuDS retrofit. This paper focuses on the construction costs associated with a range of SuDS devices likely to be implemented in a retrofit context. Three distinct types of costs have been prepared. The costs of construction per device are provided as unit costs. This approach does not, however, enable devices to be compared in terms of an area served. For this reason, schemes have been designed and costed according to representative contributory areas, such as a residential roof or a small car park. These contributory area-based cost comparisons are embodied within a decision-making framework for retrofit SuDS. A case study highlights how secondary costs need to be combined with device unit costs accurately to cost the construction of a whole scheme. The evaluation indicates that infiltration basins represent the cheapest form of SuDS to construct, followed by soakaways, ponds, infiltration trenches and porous pavements. This ranking does not, however, take account of land purchase or sterilisation costs, potential conflicts with requirements for high-density developments or other life-cycle costs—these could alter this preference ranking significantly.

Sustainable urban drainage systems (SUDS), or urban green infrastructure for stormwater control, emerged for more sustainable management of runoff in cities and provide other benefits such as urban mitigation and adaptation to climate change. Research in Spain began a little over twenty years ago, which was later than in other European countries, and it began in a heterogeneous way, both in the SUDS typology and spatially within the peninsular geography. The main objective of this work has been to know through bibliographic review the state of the art of scientific research of these systems and their relationship with the different types of climates in the country. These structures have a complex and sensitive dependence on the climate, which in the Iberian Peninsula is mostly type B and C (according to the Köppen classification). This means little water availability for the vegetation of some SUDS, which can affect the performance of the technique. To date, for this work, research has focused mainly on green roofs, their capabilities as a sustainable construction tool, and the performance of different plant species used in these systems in arid climates. The next technique with the most real cases analyzed is permeable pavements in temperate climates, proving to be effective in reducing flows and runoff volumes. Other specific investigations have focused on the economic feasibility of installing rainwater harvesting systems for the laundry and the hydraulic performance of retention systems located specifically in the northeast of the Iberian Peninsula. On the contrary, few scientific articles have appeared that describe other SUDS with vegetation such as bioretention systems or green ditches, which are characteristic of sustainable cities, on which the weather can be a very limiting factor for their development.

The use of decentralised, sustainable urban drainage systems (SUDS) for the treatment of stormwater runoff is becoming increasingly prevalent in Germany. Decentralised SUDS can offer a viable and attractive alternative to end of pipe treatment systems for stormwater runoff from urban areas. However, there is still some uncertainty regarding the long-term performance of SUDS, and the general legislative requirements for SUDS approval and testing. Whilst the allowable pollution levels in stormwater runoff that infiltrate into ground and/or water table are regulated across Germany by the Federal Soil Protection Law, there is presently no federal law addressing the discharge requirements for surface water runoff. The lack of clear guidance can make it difficult for planners and designers to implement these innovative and sustainable stormwater treatment systems. This study clarifies the current understanding of urban stormwater treatment requirements and new technical approval guidelines for decentralised SUDS devices in Germany. The study findings should assist researchers, designers and asset managers to better anticipate and understand the performance, effective life-spans, and the planning and maintenance requirements for decentralised SUDS systems. This should help promote even greater use of these systems in the future.

Urbanisation has led to numerous challenges in terms of stormwater management and environmental impact. Sustainable Urban Drainage Systems (SUDS) have emerged as a promising approach to mitigate these challenges by mimicking natural processes and providing environmentally sound water disposal systems. This review paper provides a comprehensive overview of the status of SUDS on a global scale, focusing on their development, challenges, and environmental benefits. This review paper discusses various SUDS techniques, including permeable paving, green infrastructure, and detention ponds, and highlights their effectiveness in reducing stormwater runoff, improving water quality, and enhancing ecological services. The paper also identifies the challenges faced in implementing SUDS, including technical complexity, lack of common platforms for SUDS models, limited operational experience, and institutional barriers. Additionally, the paper presents potential solutions to overcome these challenges, such as promoting research and development, providing training and capacity-building programs, and establishing guidelines and standards for SUDS design. The findings and recommendations presented in this paper contribute to the development of sustainable urban environments and the enhancement of overall environmental conditions.

The progressive industrialisation and urbanisation of urban areas have significantly altered hydrological factors such as terrain, imperviousness, and surface flow. These developments, accompanied by increased traffic congestion and carbon emissions, contribute to climate change. Consequently, implementing Mass Rapid Transit (MRT) systems is crucial for alleviating traffic congestion and reducing carbon emissions globally. However, the changes in urban hydrology following development, combined with increased rainfall due to climate change, exacerbate risks of flooding, erosion, and sedimentation for the MRT development and surrounding low-lying areas. Therefore, researching urban drainage systems under climate change conditions for MRT development is essential. This study utilised 1D/2D hydrodynamic modelling and simulation to investigate the performance of an existing MRT drainage system designed with a control-at-source concept and a new sustainable drainage system incorporating infiltration engineering and flow-retarding techniques, including porous layers and a bioecological system to mitigate urban flooding erosion and sedimentation. The results show that the new sustainable drainage system, featuring permeable pavements and bioretention facilities, effectively integrates 30% of the MRT-developed land typology without requiring additional land acquisition, which is cost-effective and practical for mitigating major flooding and reducing total suspended solids, thereby controlling erosion and sedimentation.

Policies for sustainable drainage systems in urban contexts within performance-based planning approaches

Sustainable Drainage Systems (SuDS) improve storm water management by leveraging surface runoff in urban areas while limiting the negative impacts. Integrating SuDS into the urban environments requires a systematic planning and design framework across various spatial scales. Existing studies have utilized GIS-based multi-criteria methods and Spatial Decision Support Systems (SDSS) to identify suitable locations for SuDS. However, these approaches are often subjective and do not account for the hydrologic characteristics of the catchment. Integrating SDSS tools with the Simulation – Optimization (S – O) frameworks has shown potential for addressing multiple storm water management objectives. Current S – O frameworks typically focus on providing solutions based on “which element” and “where to locate” or “which element” and “how much to allocate”. However, an ideal SuDS – SDSS should answer all the three questions: “which element”, “where to locate” and “how much to allocate”.To holistically address this problem, a novel framework integrating SDSS with a hydrologic model using an evolutionary algorithm is proposed. The framework begins with the selection of appropriate thematic layers and water balance layers obtained from a hydrologic model – Soil and Water Assessment Tool (SWAT). The weights for the selected thematic layers are calculated using Normalized Mutual Information, an objective method that quantifies how well the chosen thematic layers explain the hydrologic response of the catchment. The second part determines suitable sites for SuDS elements, viz., bio-retention cell, infiltration trench, permeable pavement, rain garden, swales through spatial overlay analysis. The S – O part of the framework involves synthetic modelling of Hydrologic Response Units (HRUs) using the Storm Water Management Model (SWMM). This model is then coupled with the Multi-Layer Green-Ampt (MLGA) based SuDS modules to simulate the runoff response for selected design storms of various return periods. Finally, the optimal combination of SuDS (“which element”) and area to be allocated are determined using the Non-dominated Sorting Genetic Algorithm (NSGA – II). The framework produces pareto-optimal solutions, enabling decision-makers to evaluate trade-offs and develop policies for planning and development.The framework is applied to the Adyar basin, covering an area of 830 km2. The optimal solutions obtained are implemented and simulated in the SWAT model to evaluate the peak flow and runoff volume reductions at the sub-basin scale. This research provides insights into how various combinations of SuDS implemented at the HRU level reduce peak flow and runoff volume at the sub-basin scale and how SuDS influence the water balance components, offering critical insights for urban planners and water resource managers.

Links between ecological and human wealth in drainage ponds in a fast-expanding city, and proposals for design and management

Amphibians have declined due to habitat loss and alteration. Sustainable Drainage Systems (SuDS) provide potential habitat for amphibians in urban landscapes. However, the contaminants they accumulate may cause increased pollutant exposure, and limited research has addressed whether differences in water quality between SuDS and natural ponds might restrict their use by amphibians. This study aimed to explore the effects of water quality on amphibian breeding and development in SuDS and natural ponds in East Kilbride, Scotland. A generalised linear modelling approach was employed to determine sources of variation in common frog (Rana temporaria) breeding and development in relation to pond size, pH, electrical conductivity (EC), chlorophyll and heavy metal concentrations. Key findings included that EC indicative of salt pollution was higher in SuDS than natural ponds, amphibians bred in both site types, but frog spawn clump densities were lower in SuDS, and tadpole development rates were higher in SuDS sites but decreased when aluminium concentrations exceeded concentrations those of surface water standards. However, pond desiccation was a significant element in the 2018 study year. It was concluded that natural ponds and SuDS varied in water quality but were important in supporting amphibian populations. However, water quality might influence amphibian development more than breeding attempts; implications and management recommendations are highlighted based on these observations.

Flooding in the Manhaua neighborhood is caused by changes in the hydrological cycle, topography, soil impermeabilization, and inadequate land use. These floods have economic, social, and public health impacts. Sustainable Urban Drainage Systems (SUDS) are alternatives that aim to increase the infiltration of rainwater into the soil and control surface runoff to minimize this problem. The objective of this study was to develop an improvement plan for the current rainwater drainage system in the Manhaua neighborhood in Quelimane city. To achieve the proposed objectives, interviews were conducted with the local community and the Quelimane City Council to characterize the drainage system and identify the related issues of rainwater. A mapping of flood-prone areas was also carried out using the Analytic Hierarchy Process (AHP) and the development of a mathematical model with weightings of influencing factors, through the ArcGIS Software. As a result, possible solutions were proposed, involving both structural and non-structural measures throughout the study area, such as permeable pavements, detention basins, and tree planting. It is concluded that the application of SUDS represents an evolution in drainage systems, not replacing conventional systems but complementing and improving the existing ones.

Urban runoff frequently carries elevated concentrations of heavy metals such as nickel (Ni), posing significant environmental and public-health risks. Sustainable Urban Drainage Systems (SUDS) offer a promising pathway to mitigate these impacts, particularly through the use of filter media that enhance water decontamination. This study evaluates Filtralite, a lightweight expanded clay aggregate, as a filtration medium for Ni removal, with special emphasis on the evolution of pH under prolonged operational conditions and on the influence of particle size on the material’s treatment capacity.The research was based on an 80-day experiment designed to simulate an accelerated weathering process similar to what occurs under real operating conditions when SUDS interact with rainfall. Four granulometric fractions (2 mm, 1 mm, 0.5 mm, and 0.25 mm) were tested under controlled, repeated washing cycles carried out statically: the Filtralite was kept submerged in beakers, and its water was replaced on an approximately daily basis throughout the 80-day period. The pH values of the effluent were systematically recorded and interpreted as a proxy for the material’s alkalinity-generating capacity—an essential driver of Ni removal from the contaminated solution.Results demonstrate a consistent granulometry-dependent pattern in pH evolution. Coarser fractions (2 and 1 mm) experienced a more rapid decline in alkalinity than finer ones: although initial effluent pH values exceeded 10, they dropped below the threshold required for efficient Ni precipitation (≈8.5–9) after only a few litres of cumulative washing. The 2 mm fraction dropped to pH 8–8.5 after approximately 8–10 L of equivalent runoff, suggesting a short effective lifespan in real SUDS applications. The 1 mm fraction exhibited a slower decline, maintaining pH > 9 for a longer period, but ultimately converging toward circumneutral values at extended washing volumes. In contrast, finer fractions (0.5 and 0.25 mm) preserved alkaline conditions throughout most of the experiment. The 0.5 mm material sustained pH values in the range 9–10 for the majority of the test, indicating a more stable and gradual release of alkaline species. The finest fraction (0.25 mm) provided the most robust performance: effluent pH consistently remained between 9.5 and 10 even under high cumulative washing volumes, reflecting the strong buffering capacity associated with its larger specific surface area.Overall, the findings confirm that Filtralite is an effective and sustainable medium for Ni removal in SUDS, although its long-term performance is highly sensitive to granulometry. Fine fractions provide a prolonged alkaline environment that enhances precipitation-driven removal. These results suggest that finer Filtralite may offer favourable characteristics for potential field applications, supporting more stable and efficient metal removal over extended periods. However, the reduced particle size also implies lower hydraulic conductivity compared to coarser fractions, which could limit infiltration performance in practical implementations. Validation under real operating conditions is therefore still required.