Urban Water Systems Research Articles

Prevalence, production, and ecotoxicity of chlorination-derived metformin byproducts in Chinese urban water systems

The widely used antidiabetic drug metformin has become an emerging contaminant of water systems. In a prior study, we demonstrated the marked mammalian toxicity of the disinfection-derived byproducts (DBPs) Y (yellow, C4H6ClN5) and C (colorless, C4H6ClN3), and here assess the distribution, formation, and ecotoxicity of these in Chinese urban water systems. A national tap water assessment showed that metformin and C concentrations were higher in large, dense urban areas and surface water sources than in sparsely populated areas and groundwater sources. Water types' analysis clearly showed that C derived from chlorination of metformin-contaminated water (up to 4308.5 ng/L) circulated from domestic water (0.7–9.7 ng/L) via sewage (2.3 ng/L in effluent) to surface water (0.6–3.5 ng/L). Simulated disinfection and aqueous stability results systematically showed rapid formation and 24 h stability of both byproducts, indicating high exposure odds for water users. Both byproducts showed clear but distinct toxic effects on the growth (72 h IC50, 0.6 mg/L for Y and 4.4 mg/L for C) and photosynthesis of the microalgae Pseudokirchneriella subcapitata at milligram levels. Combinedly, our work reveals that metformin byproducts have been disseminated to urban water cycle and contaminated tap water, increasing potential toxic risk for drinking water. Its outcomes provide a preliminary reference for future studies on the environmental fate and ecotoxicological effects of unintended DBPs formed in the chlorination of metformin-contaminated water.

Exploring alternative practices in urban water management through the lens of circular economy–A case study in the Barcelona metropolitan area

Urban water management has recently been questioned because of the fragmented nature of the urban water system and its linear model. The integration and management of water systems are currently recognized as a socio-technical challenge that must be addressed for a more sustainable urban water management. In the short term, a key factor for its transition will be integration of alternative practices that allow for experimentation, learning, and scaling up. This study aims to identify potential shifts supported by two alternative practices for water reuse: nature-based solutions and water reuse technologies, using circular economy principles as analytical categories. The research uses a case study, the Besòs river of the Barcelona metropolitan area, to show that: i) improving biodiversity and water quality helps to regenerate natural capital; ii) water reuse for streamflow augmentation keeps resources in use and promotes synergies, which benefits social livability; and iii) risk management and a potential fit-to-purpose strategy can marginally help to avoid waste externalities. This research has shown that the CE principles are applicable as a framework for identifying the interconnected shifts promoted by water systems. A reflexive understanding of the alternative practices provides deeper insight into the experiences, barriers, and shifts that allow innovative interactions in specific urban contexts and can deliver additional benefits for society. This knowledge can be useful for integrated urban management; however, further integration of cross-sectoral collaboration and flexibility are required.

Investigating the implementation of Indonesian regulation in drinking water supply system

Drinking water is an aspect of development that has an essential function in supporting community welfare because it relates to health, social and economic conditions. Therefore, the urban water system needs good planning, design, and operational infrastructure. This paper aims to identify actors and their roles in the drinking water supply system in Indonesia. Analysis was carried out on laws and regulations related to drinking water through content analysis. The results showed that government capacity in building and administering drinking water supply system was still lacking. In addition, the government shared the responsibilities to enterprises, both owned by the government and by private institutions. Finally, it is necessary to equip and expand laws and regulations to provide drinking water distribution. The critical implication to stop the massive exploitation of groundwater for consumption includes the improvement of drinking water reliability by synergizing and integrating all attempts by various actors in providing drinking water.

Implications of the Urban Water and Food Systems Governance Nexus for Household Food Security in the City of Gweru, Zimbabwe

Innovative water governance practices are essential to achieve sustainable cities through robust public policies and stakeholder engagement. This study assessed the dynamics of water service delivery in Gweru and its impact on household food security. The study focused on the city’s food sources, water service pricing, power struggles in decision-making, and the implications for household food security. A household survey was conducted with 489 respondents selected by stratified random sampling. Interviews with purposively enrolled key informants and observations were also used. Findings revealed a multi-faceted scenario of water governance challenges that crippled household food security. Food purchases and farming, the primary household food streams for the city, were under threat due to water shortages and high monthly water bills. More than 90% of household incomes were below the Poverty Datum Line and the Total Consumption Poverty Line; water bills accounted for a significant portion, ultimately causing food insecurity. The grant-aided municipality emphasized revenue collection to mitigate the central government’s 2013 debt cancellation. Gweru had no useful alternative sources of water for agriculture. The existing water governance failed to capture the complex symbiotic relationship between the city’s water and food availability. While we advocate minimal central government interference, the municipality must introduce an efficient dual-purpose water system to protect residents, the natural environment, and the local authority’s finances.

Water Sensitive Cities: An Integrated Approach to Enhance Urban Flood Resilience in Parma (Northern Italy)

Climate change is globally causing more intense meteorological phenomena. Our cities experience increased rainfall intensity, more intense heat waves, and prolonged droughts providing economic, social, health and environmental challenges. Combined with population growth and rapid urbanization, the increasing impact of climate change will make our cities more and more vulnerable, especially to urban flooding. In order to adapt our urban water systems to these challenges, the adoption of newly emerging water management strategies is required. The complexity and scale of this challenge calls for the integration of knowledge from different disciplines and collaborative approaches. The water sensitive cities principles provide guidance for developing new techniques, strategies, policies, and tools to improve the livability, sustainability, and resilience of cities. In this study, the DAnCE4Water modeling approach promoting the development of water sensitive cities was applied to Parma, an Italian town that has faced serious water issues in the last few years. The city, indeed, had to face the consequences of flooding several times, caused by the inadequacy of both the network of open channels and the sewerage network due to the urban expansion and climate change of the last 30 years. Through the model, the efficiency of decentralized technologies, such as green roofs and porous pavement, and their integration with the existing centralized combined sewer system was assessed under a range of urban development scenarios. The obtained results show that the adoption of an integrated approach, including soft engineering hydraulic strategies, consisting in the use of natural and sustainable solutions, can increase resilience to urban flooding. Further, the study shows that there is a critical need for strategic investment in solutions that will deliver long-term sustainable outcomes.

The influence of temporal variability and reservoir management on demand-response in the water sector

Urban water systems can be highly energy intensive. Yet, they are also excellent candidates for demand-response since they possess readily controllable operations and large amounts of storage. However, real-worlds trials have delivered mixed results, which implies the need to understand the underlying mechanisms of flexibility in water operations. This paper studies the potential to shift energy demand in an urban water system located in the River Thames basin, a region encompassing the city of London, England. Results show that the system could theoretically shift up to 20.1% of its annual energy demand for pumping (2.1 GWh), saving the local water utility around £5.6 million in electricity costs. However, the water system’s flexibility is shown to be highly variable due to the variability in water demands and electricity prices, in-turn affecting the financial returns from demand-response. Sensitivity analysis reveals that factors such as the seasonal reservoir control strategies and total storage capacity are key determinants of system flexibility. A relationship between water storage capacity and flexibility is also derived, which could be used to estimate water sector flexibility in other regions.

How does community-managed infrastructure scale up from rural to urban? An example of co-production in community water projects in Northern Pakistan

This paper examines the role of participation, co-production and community management in a random sample of 50 rural and urban water systems under the Water and Sanitation Extension Programme (WASEP) in Gilgit-Baltistan, Pakistan. It looks at the role of an NGO (the Aga Khan Agency for Habitat) in co-production, and how this model of community-based water management (CBWM) contributes to the discussion in the literature. Specifically, the paper considers whether the largely rural WASEP model can be successfully scaled up and scaled out to urban centres, drawing on evidence from a survey of over 2,500 rural and urban households. The findings illustrate the importance of participation in the successful delivery of water systems. However, higher levels of rural participation are related to specifically rural features, including the smaller size and more limited diversity of communities. The paper concludes that new methods may be required for the transfer of CBWM to urban centres with much larger, more diverse and growing populations.

SWMM-Based Assessment of the Improvement of Hydrodynamic Conditions of Urban Water System Connectivity

SWMM-Based Assessment of the Improvement of Hydrodynamic Conditions of Urban Water System Connectivity

Transport and sources of nitrogen in stormwater runoff at the urban catchment scale

Revealing the transport and sources of nitrate in urban stormwater runoff can effectively manage nitrate pollution in urban areas. This study used the chemical properties of stormwater along with δ15N-NO3− and δ18O-NO3− isotopes to identify the transport and sources of nitrate within an urban catchment. The results showed that the NO3-N concentration and total dissolved nitrogen (TDN) composition differed among roof runoff, road runoff, and drainage runoff. The highest NO3−N concentration was found in roof runoff and NH3-N dominated the TDN composition. However, the erosion of pervious surfaces and litter may have led to higher DON/TDN values in road runoff. The TDN composition of drainage runoff was consistent with that of roof runoff. Furthermore, among the various rainfall characteristics, the depth and intensity of rainfall were significantly correlated with the NO3-N concentrations in roof runoff and road runoff, while antecedent dry days had little effect. According to a Bayesian mixing model, the average contributions of the nitrate load in drainage runoff were ranked as road runoff (51.6%) > rainwater (29.2%) > and roof runoff (15%), which is consistent with the results of previous studies. Rainwater nitrate may have ranked second due to the confluence time, pollution level, and other factors that made rainwater reduce the pollution characteristics of roof runoff. The dominant contribution of road runoff to the NO3−N concentration of drainage runoff could be attributed to the large runoff volume. Hence, effective measures should be taken to minimize the NO3-N concentration in roof runoff, while runoff volume reduction should be the primary concern for controlling road runoff pollution. This work is helpful for obtaining a better understanding of the transport and sources of nitrate that vary dynamically within different hydrological flow pathways, and the outcomes are expected to enhance targeted measures to mitigate nitrate pollution in urban water systems.

Short Term Real-Time Rolling Forecast of Urban River Water Levels Based on LSTM: A Case Study in Fuzhou City, China.

Water level management is an important part of urban water system management. In flood season, the river should be controlled to ensure the ecological and landscape water level. In non-flood season, the water level should be lowered to ensure smooth drainage. In urban areas, the response of the river water level to rainfall and artificial regulation is relatively rapid and strong. Therefore, building a mathematical model to forecast the short-term trend of urban river water levels can provide a scientific basis for decision makers and is of great significance for the management of urban water systems. With a focus on the high uncertainty of urban river water level prediction, a real-time rolling forecast method for the short-term water levels of urban internal rivers and external rivers was constructed, based on long short-term memory (LSTM). Fuzhou City, China was used as the research area, and the forecast performance of LSTM was analyzed. The results confirm the feasibility of LSTM in real-time rolling forecasting of water levels. The absolute errors at different times in each forecast were compared, and the various characteristics and causes of the errors in the forecast process were analyzed. The forecast performance of LSTM under different rolling intervals and different forecast periods was compared, and the recommended values are provided as a reference for the construction of local operational forecast systems.

SUSTAINABLE LAKE/SITU MANAGEMENT

The increasingly advanced developmentnin the city of Bogor has an impact on the carrying capacity of the environment. One that is rarely in the spotlight is about the decreasing number of lakes in Bogor. In urb an areas such as Bogor City, local people refer to the lakes as situ or setu. The existence of these “Situ”
 affects the water system, both in this city and in the surrounding areas. Although “Situ” play a vital role in maintaining the balance of urban water systems, they have not received sufficient attention in the planning documents for the City of Bogor, both annual and medium-term documents. The rapid development of the city affects thequantity and quality of urban lake water in the city of Bogor. These “Situ continue to experience physical and ecological degradation which increases the threat to the health of the population of the city of Bogor. This situation shows that the site has not been managed and functioningnproperly. Human and natural disturbances such as encroachment, garbage disposal, and untreated waste have polluted “Situ” water and reduced its volume capacity. Most of the lakes in the city of Bogor experience disturbances in damaged environmental conditions. This paper seeks to examine th e condition of the “Situ” in Bogor City and its problems based on literature studies from previous researchers. The results of the research will provide recommendations based on scientific theories and existing regulations, both national regional regulations and regional regulations in Bogor City

Characterising microplastic pollution in sediments from urban water systems using the diversity index

As microplastic pollution (MP) is currently attracting worldwide attention, the characterisation of microplastics (MPs) in terms of pollution level, sources and migration is of great importance. In the present work, both the Simpson diversity index (SDI) and Shannon-Wiener index (SWI) were used to study the MPs present in the sediments from urban water systems including two lakes (Yushan lake and Nan Lake) and two rivers (Yushan River and Yongfeng River) from Ma'anshan City in the lower reaches of the Yangtze River. The abundance of MPs in sediments ranged between 5 and 153 items·kg−1 with high spatial variation depending on the site. MPs detected in the urban water system were dominated by film (69.8%) in shape, transparent (36.4%) in colour, <1000 μm (50.1%) in size, and Polyethylene (PE, 43.3%) and Polypropylene (PP, 35.5%) in composition. Whilst previous studies have used the diversity of MPs to analyse MP in marine environments, this work aims to obtain the diversity information of MPs in urban areas. The diversity indices of polymer, shape, colour and size were 0–0.685, 0–0.578, 0–0.810 and 0–0.816 for SDI, respectively, and 0–1.255, 0–0.935, 0.1.710 and 0–1.748 for SWI, respectively. Pearson analysis indicates a significant correlation between the number of land-use types and the diversity index of MPs (r = 0.507–0.935, p < 0.05 for SDI; r = 0.528–0.857, p < 0.05 for SWI). Additionally, an attractive fitting relationship between SDI and SWI (p < 0.001) was observed in MP analysis. This means that either of the SDI and SWI can be employed for the analysis of MP. Sites where the urban water system flows into the Yangtze River had a higher abundance of MPs (96 ± 66 items·kg−1) than the urban water system (33 ± 30 items·kg−1) (t = −2.727, p = 0.01), implying that MPs tend to accumulate after they enter the Yangtze River from the urban water system.

Assessing sustainability through the Institutional Grammar of urban water systems

AbstractUrban water supply systems in the United States are designed to be robust to a wide range of historical hydrological conditions in both their physical infrastructure and in the institutional arrangements that govern their use. However, these systems vary greatly in their capacity to respond to new and evolving stressors on water supplies, such as those associated with climate change. Developing a more precise understanding of the complexity of interactions between the environmental and human components of urban water systems, specifically via their institutions, has the potential to help identify institutional design choices that can foster proactive transitions to more sustainable operating states. This article adapts the Institutional Grammar (IG) within the Robustness of Coupled Infrastructure Systems Framework to assess how a heavily engineered system's institutional configuration may impact its ability to transition to more sustainable management practices. While use of the IG has historically been limited in larger‐N studies, our application demonstrates its flexibility in revealing variation in specific components across cases. The analysis finds the structure of formal institutions shape the interactions between actors differently, and that institutional diversity exists across environmental contexts. The extent to which this institutional diversity drives transitions remains an open question. The results highlight both the importance of and challenges involved with developing longitudinal data on social and natural system interactions.

Rigid Versus Variable Energy Sources in Water-Pressurized Systems: An Economic and Environmental Analysis

The layouts of most urban water systems are known. A head tank with an appropriate elevation is used to supply water through the network at a pressure equal (or higher) to that set by the relevant standards. Furthermore, equalization, fire and emergency storage are important benefits of tank use, as is the possibility of avoiding peak rate electricity fares. However, at the end of the last century, some tanks were reported to have a negative impact the quality of water, and recommendations were made to limit their volume and revise their geometry. Recently, alternative options have been considered. Equalization can be achieved with pumps with variable-frequency drivers, emergency situations can be avoided with electric oil generators and solar plants can be used to offset other generation types and reduce energy costs. Therefore, this article analyses the performance of tanks as an energy source, and tank and pump supply methods are directly compared; overall, direct supply through pumps is cheaper, more energy efficient and more environmentally convenient. Therefore, in the context of climate change, it seems reasonable to avoid water tanks as energy sources.

Water Infrastructure: Does the US Need a National Policy?

Although its investment needs lag the dominant transportation category, water infrastructure addresses human needs at a foundational level because it plays public health and economic roles. Much of it is old and not likely to be replaced soon, so federal policy must focus on intergovernmental leadership to sustain vital dams, urban water systems, and natural systems. Fixing the federal responsibility requires attention to intergovernmental relations and the conflicting goals of investment and regulation. Regulatory reform is ongoing, and normally not amenable to political initiatives. Federal water policies for both investment and regulatory controls seem to be on a flat trajectory, which is expected because they have evolved over decades. These can be summarized as: maintain federal dams and levees, invest in small grants and leveraging funds for state and local governments, address water justice issues, and operate essential programs like flood insurance. Public health and safety concerns will continue to dominate, more than in other infrastructure sectors. The future of water investments will be to hold the course with occasional shifts to respond to emergencies and new opportunities, such as greater private sector involvement.

Effects of microhabitat characteristics on amphibian diversity in urban water system of Kaifeng, Henan, China.

Amphibians with a unique life history are extremely sensitive to environmental changes. They are important indicator species for environmental change. The construction of Kaifeng water system affects the habitat and biodiversity of amphibians. In this study, we investigated the amphi-bians in water system of Kaifeng by setting sample points and using visual encounter method, and measured the habitat variables. We quantified amphibian biodiversity under different habitat types using the Shannon diversity index, Pielou evenness index and Simpson dominance index, and explored the responses of amphibians to microhabitat variations by cluster analysis and redundancy analysis. The results showed that the diversity, evenness, and dominance of amphibians in the natural revetment were higher than those in the artificial hardened revetment, indicating a more stable amphibian population in the natural habitat. The dominance index of amphibians on natural revetment was higher than that of the two artificially hardened revetments, indicating that amphibians preferred natural habitat. The abundance of both Palophylax nigromaculata and Bufo gargarizans had significant positive correlation with night light intensity, while the abundance of P. plancyi was positively correlated with total phosphorus, and that of Fejervarya limnocharis was positively correlated with water pH. The protection of amphibians should be considered in the construction of urban water system in Kaifeng. The presence of more natural revetment would be of great significance to enhance amphibian biodiversity.

Modeling spatial diffusion of decentralized water technologies and impacts on the urban water systems

Understanding the market demand for decentralized water technologies and the impacts on the urban water systems (UWS) is critical to sustainable promotion in urban communities. In this paper, we developed a spatial agent-based model (ABM) that simulates the adoption of home-based rainwater harvesting (RWH) and greywater recycling (GWR) by single-family households in Boston, United States. We applied system dynamics modeling (SDM) to evaluate the impacts of decentralized technologies on the UWS. The change in carbon emissions of the UWS was modeled as the environmental benefit for household choice decisions in ABM. We validated our integration by comparing the simulated reservoir elevations with the reference-year values and comparing where early adoptions emerge with the reported installations. In the results, we first examined the sensitivity of the adoption and diffusion to the market promotion, neighbor's influence, environmental benefits, and economic attractiveness. Our simulation highlights the diffusion from central downtown to the suburban. RWH has higher adoptions than GWR, and RWH starts diffusing much earlier. Reservoir water availability is improved through the adoption of RWH and GWR. As the tradeoffs, reservoirs discharge more water for storage security, and hydropower generation becomes less as the need of water transfer decreases. The UWS do not reduce carbon emissions due to the high electricity consumption of GWR. Utilizing the improved water resources and reducing the impact of decentralized technologies are required for sustainable promotion of water decentralization. Our integrated modeling can be improved by including more critical socio-technical interactions for spatial planning of decentralized water technologies.

Profiles of environmental antibiotic resistomes in the urban aquatic recipients of Sweden using high-throughput quantitative PCR analysis

Antibiotic resistance in aquatic ecosystems presents an environmental health issue worldwide. Urban recipient water quality is susceptible to effluent discharges with antibiotic resistance contaminants and needs to be protected, particularly for those as sources of drinking water production. Knowledge on aquatic resistome profiles in downstream of wastewater treatment plants allows a better understanding of the extent to which antibiotic resistance contaminants emerge and spread in recipient waters, but such information remains very limited in Sweden. The key objective of this study was to determine the resistome profiles of numerous antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and other genes in urban recipient water systems connected to Sweden's major drinking water reservoir. This was achieved through analysis of surface water samples for 296 genes using high-throughput quantitative PCR arrays. A total of 167 genes were detected in at least one of the samples, including 150 ARGs conferring resistance to 11 classes of antibiotics, 7 integrase MGEs and 9 other genes. There was a spatial difference in the resistome profiles with the greatest average relative abundance of resistance genes observed in the water body of Västerås followed by Uppsala, Stockholm and Eskilstuna, as similar to the general pattern of the antibiotic sales for these regions. ARGs against β-lactams and sulfonamides showed the highest average relative abundance in the studied water bodies, while vancomycin resistance genes were only found in the Uppsala water environment. Generally, the recipient water bodies were detected with higher numbers of genes and greater relative abundances as compared to the upstream sites. Anthropogenic pollution, i.e., wastewater discharge, in the recipient water was also reflected by the finding of intI, sul1 and crAssphage. Overall, this study provided the first quantitative assessment of aquatic environmental resistomes in Sweden, highlighting the widespread of antibiotic resistance contaminants in urban recipient waters.

Optimization of wastewater treatment strategies using life cycle assessment from a watershed perspective

Increasing the environmental sustainability of wastewater treatment contributes to the construction of sustainable urban water systems, especially for developing countries. Life cycle assessments (LCA) have quantified the environmental implications of overly-sophisticated discharge standards. However, studies on these topics provide limited practical guidance, as real policy concerns are rarely incorporated in the assessment process. One such concern is watershed management by satisfying the water quality limit (WQL) of the receiving environment. To manage sustainable wastewater treatment from a watershed perspective, this study integrates LCA with water quality models to facilitate the decision process. By parameterizing the WQL as a constraint condition, a hierarchical priority structure is established in the environmental index system, and alternatives that satisfy the WQL are screened, and compared in terms of life cycle burdens. This study investigates the effect of considering WQL on the evaluation of wastewater treatment strategies, using an urban sewage system case study in China. In wastewater treatment plants (WWTPs), determining discharge levels based on the WQL of the receiving river, contributes to specific control of WWTPs with reduced life cycle burdens, compared with the “one size fits all” administrative strategy. Considering the influence of non-point source pollution (urban runoff), results demonstrate that only relying on wastewater treatment is unlikely to reliably satisfy the WQL. This study highlights the importance of utilizing an integrated policy to coordinate the treatment of wastewater and urban runoff for watershed management, by coupling enhanced wastewater treatment intensities with the green and gray storm water management infrastructures. This integrated policy quantitatively showed advantages in terms of stable control of water pollution, and less dependence on the self-purification capacity of the receiving river.

Study on Key Technologies of Ecological Civilization of Lishui Ancient City Water System

Starting from the historical dimension, this paper studies the historical documents and engineering cases of ancient water conservancy projects in Lishui, explores the transformation law of urban water system in Lishui, and summarizes the key technologies of water ecology contained in ancient water control practice. It was found that Chuzhou took advantage of geographical, geological and climatic conditions, followed the overall balanced water control strategy, planned the ancient city water system network, and completed the task of water distribution. Among them, guided by planning technology, supplemented by canal system network, water and sediment regulation, flood control, interchange diversion and other technologies, a perfect water system is finally formed, which can provide reference for modern water conservancy projects construction.