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The Bongani River is a primary source of polluted stormwater runof discharging into the shallow Ashmead Channel, a portion of the Knysna Estuary situated on the southern coast of South Africa. One of the ways to improve the quality of stormwater in the Bongani River is to introduce sustainable drainage systems (SuDS) into the catchment area to improve stormwater management. The feasibility of reducing nutrient loads using SuDS was investigated using a continuous hydrological model of the Bongani River and its catchment. Besides the current situation (Current Scenario), various scenarios were developed in PCSWMM (Personal Computer Stormwater Management Model). The total phosphorus reduction objective for SuDS set by the City of Cape Town (used in the absence of Knysna-specific stormwater quality objectives) is 45%. All the scenarios modelled showed pollutant load reductions of between 47% and 78%, exceeding the 45% target, but none approached the pre-development baseline which indicated some 89% and 90% lower concentrations of total nitrogen and total phosphorus, respectively, compared to current conditions. This performance gap highlights the extent of nutrient enrichment in the Bongani River catchment and suggests that, while SuDS can provide improvements, additional watershed-scale interventions are necessary to restore water quality conditions.

Chatty River, located in Gqeberha, South Africa, is the largest tributary feeding into the Swartkops Estuary, and a major source of pollution. Its catchment is mainly occupied by low-income residential areas resulting in polluted stormwater runof from litter and raw sewage discharge. This study employed both experimental and modelling approaches to assess pollution sources and mitigation options. Water quality sampling was conducted across various sub-catchments draining into the Chatty River, and subsequently Swartkops Estuary, to evaluate the physical, nutrient, and microbiological characteristics, revealing eutrophic and hypertrophic conditions and high gastrointestinal health risks to residents. Additionally, hydrological and hydraulic modelling were performed using PCSWMM (Personal Computer Stormwater Management Model) for the Bethelsdorp River sub-catchment. Various scenarios were developed to test the retrofitting of sustainable drainage system (SuDS) interventions for improving water quality. The model scenarios include: the 'As-Is' model representing the current situation; the 'Pre-Development' model representing the state before the influence of anthropogenic activities, and various retrofitted SuDS intervention models, including the reduction of pollutant concentration through the rehabilitation of historic wetland areas, a constructed wetland, a retention pond, and various infiltration practices. Rehabilitating the wetlands ofered the highest impact in terms of water quality improvement, with a mean pollutant reduction of 30%. However, a combination of all the interventions had the highest pollutant removal when functioning eficiently, of 72% and 80% for dissolved inorganic phosphorus (DIP) and total suspended solids (TSS), respectively. Forming a treatment train was seen as the most efective strategy to adequately improve water quality in the catchment to meet the standards presented by various guidelines.

Effective decision-making in urban water infrastructure optimization, particularly in sustainable urban drainage systems (SuDS), hinges on navigating complex multi-objective problems. This study addresses the challenge of sparse Pareto-fronts in many-objective SuDS design, often caused by algorithmic limitations and the intricate objective function interactions, impacting the availability of diverse design alternatives for decision-makers. To tackle these challenges, this research proposes a novel framework that integrates advanced data imputation and surrogate modeling techniques. The framework uses artificial intelligence methods to populate the sparse regions by replicating the Pareto-front structure, predicting decision variables to guide further simulations and find efficient solutions without repeated optimization runs. The methodology is validated through a SuDS design case study located in Ann Arbor, Michigan. Following the initial optimization, sparse regions were identified in four of the eight objective functions. Using the proposed framework, 32 new and efficient SuDS designs were introduced into the sparse regions without additional optimization, enhancing the uniformity of the Pareto front. This study enhances decision support tools in urban flood management by increasing the informativeness of design alternatives available to planners and engineers.

In recent decades, the impacts of urbanization on the hydrological cycle have led to an increase in the frequency and magnitude of urban flooding events, and this is also amplified by the effects of climate change. Sustainable Drainage Systems (SuDS) provide a revolutionary change in this field, improving the sustainability and resilience of cities. This research explores the integration of different SuDS with the aim of significantly reducing both the flow volume and celerity of floods in a residual urban catchment area of the metropolitan city of Querétaro (Mèxico), where extreme rainfall frequently occurs. This catchment is a representative suburb of urban pressure and environmental degradation problems. Currently, managing storm water under climate uncertainty through a multi-disciplinary approach is a major concern in this urban area. A 1D–2D coupling model of shallow water equations, the finite volume method, an unstructured meshing method, and a hybrid parallel computing application defined the optimal configuration of SuDS at catchment scale to reduce the flood vulnerability in Querétaro. Specifically, in this paper, we explore the management issues of the proposed SuDS configuration that acts as a water resource system with multiple purposes. A generic simulation model called MODSIM was applied to simulate the designed urban drainage system under a balanced IPCC future climate scenario in terms of reliability, resilience and vulnerability against water scarcity. The proposed hierarchical Reliability–Resilience–Vulnerability approach appears to be effective in evaluating the system performance, showing that the complete satisfaction of non-essential water uses in Querétaro can be assured at a 65% rate of reliability for a large range of reservoir storage conditions.

Sustainable drainage systems (SuDS) can be a key tool in the management of extremes of rainfall, due to their capacity to attenuate and treat surface water. Yet, implementation is a complex process, requiring buy-in from multiple stakeholders. Buy-in is often undermined by a lack of practical evidence and monitoring of implemented SuDS. In this paper, we present a collaborative case study between a local authority, university and the UK Environment Agency. This partnership approach enabled the installation of SuDS and monitoring equipment to address surface runoff in the north east of England. Ultrasonic sensors were installed in the drainage network to evaluate the attenuation of surface water. SuDS were installed during an atypically wet spring, followed by a hot and dry summer, providing a range of conditions to assess their performance. Results demonstrate that there was a statistically significant difference in the detected flow level in manholes downstream of the SuDS interventions. Several challenges occurred, from signal obstacles in wireless telecommunication services, to logistical constraints of installing sensors in the drainage network, and issues with the adoption of property level SuDS. These issues require further research. Qualitative support for partnership working was crucial to increase the capacity for delivering SuDS. To ensure the success of future schemes and likelihood of SuDS uptake, partnership working and engaging with communities is vital.

Urban flooding is an increasingly common phenomenon around the world. The reasons are usually attributed to the insufficient capacity of the combined sewer system and its inability to adapt to the changing dynamics of rainfall. This is also the case in Warsaw (the capital of Poland), where the sewage system was designed in the 1960s. The aim of the article is to highlight possible hydrological solutions that would significantly improve Warsaw’s situation in terms of rainfall runoff. The article looks at some solutions that were previously mentioned in the literature and presents an assessment of the possible changes in land use/land cover on the hydrological processes and improvements in the general hydrological situation of Warsaw. In addition, the article points out the need to update the programme and spatial approach to the discharge of water from specific watersheds in Warsaw, as well as to establish a single manager for stormwater drainage in the city of Warsaw. An important issue is the restoration of natural retention basins in the city and the construction of artificial basins in places with frequent local flooding. The article emphasises the importance of building individual detention basins (as well as low-impact developments) for newly planned investments. Other important aspects are as follows: the construction of suitable underground or open channels, the need to disconnect Ursynów’s stormwater runoff from the catchment area of the Służewiecki Stream and to channel it along the southern bypass for Warsaw (S-2) to the dry lakes and ponds in Wilanów. Finally, the article discusses the application of Sustainable Drainage Systems (SuDS) and Real-Time Control (RTC) in urban drainage systems as a possible solution to improve wastewater management in urban areas.

Residents of informal settlements, the world over, suffer consequences due to the lack of drainage and greywater management, impacting human and environmental health. In Brazil, the presence of the Aedes aegypti mosquito in urban areas promotes infections of the Zika virus as well as companion viruses, such as dengue, chikungunya and yellow fever. By using observation and interviews with the community, this paper shows how a simple sustainable drainage system approach could prevent the accumulation of on-street standing water, and thus reduce opportunities for the mosquito to breed and reduce infection rates. During the interview phase, it became apparent that underlying misinformation and misunderstandings prevail related to existing environmental conditions in favelas and the role of the mosquito in infecting residents. This inhibits recommendations made by professionals to reduce breeding opportunities for the disease vector. Whilst unrest is an issue in favelas, it is not the only issue preventing the human right to reliable, safe sanitation, including drainage. In “pacified” favelas which may be considered safe(r), the infrastructure is still poor and is not connected to the city-wide sanitation/treatment networks.

Water scarcity has become a major problem for many countries, resulting in declining water supply and creating a need to find alternative solutions. One potential solution is rainwater harvesting (RwH), which allows rainwater to be stored for human needs. This study develops an RwH assessment system through building information modeling (BIM). For this purpose, a hydrological study of Cfa-type climate cities is conducted with the example of Islamabad, Pakistan. The monthly rainfall data of three sites were assessed to determine the volume of the accumulated rainwater and its potential to meet human needs. The average number of people living in a house is taken as the household number. Household number or of the number of employees working at a small enterprise, roofing material, and rooftop area are used as the key parameters for pertinent assessment in the BIM. The data simulated by BIM highlight the RwH potential using five people per house as the occupancy and a 90 m2 rooftop area for residential buildings or small enterprises as parameters. The results show that the selected sites can collect as much as 8,190 L/yr of rainwater (48 L/person/day) to 103,300 L/yr of rainwater (56 L/person/day). This much water is enough to fulfill the daily demands of up to five people. Therefore, it is established that the study area has an RwH potential that is able to meet the expected demands. This study presents a baseline approach for RwH to address water scarcity issues for residential buildings and factories of the future.

Flooding may cause substantial environmental, economic and human losses. This study proposes a design and assessment of sustainable retention ponds to reduce flood risk in an urban drainage system of Capiro-Bengochea, Santa Clara, Cuba. The design integrates green infrastructure principles with hydrological and hydraulic modeling tools. The study analyzed 11 rainfall events to simulate runoff behavior and the effectiveness of proposed solutions. Retention ponds significantly reduced peak runoff by up to 77%, mitigating flooding risks, enhancing urban aesthetics and offering recreational benefits while addressing technical challenges. This study introduces innovative sustainable urban drainage strategies to Cuban contexts, aligning with global practices and demonstrating the multifunctionality of nature-based solutions in stormwater management.

Climate change is arguably the greatest challenge facing cities today. Its severe consequences have created the need for sustainable urban planning. In this regard, Sustainable Drainage Systems (SuDS) have contributed in recent years to alleviating environmental problems caused by soil sealing and enhancing the resilience of cities to climate change. However, in most cases, the level of implementation is limited to solving environmental problems caused by inadequate urban planning. To change this, in recent years some countries have proposed recommendations to integrate these systems into their urban planning regulations, but these have been general and have not defined specific measures. This paper proposes to achieve this goal by using case studies of three countries with similar characteristics (Spain, Italy and France). A common framework for the integration of SuDS in planning has been proposed that can be exported to other similar places. The urban scales of intervention have been defined (city, neighborhood and street), as well as the actions to be carried out (analysis, planning and regulatory measures) and the urban plans to which they should be applied. This proposal represents an advancement in the application of SuDS as a primary control measure. This breakthrough will significantly improve the resilience of the cities of the future, making them more resilient to the effects of weather and climate change.