Quantification of stormwater runoff using a combined GIS and curve number approach: a case study for an urban watershed in the Ozark Highlands,USA

Managing stormwater runoff is crucial to preserving water quality in rapidly developing urban watersheds. The objective of this study was to develop a methodology to test existing stormwater drainage infrastructure, identify potential areas of improvement, and estimate potentially contaminated runoff by combining two widely used stormwater runoff prediction models. A watershed containing much of the University of Arkansas-Fayetteville campus was targeted for this study because stormwater from this watershed drains into a local river designated as an impaired water body due to siltation. The curve number method was used to estimate runoff for various flood-return periods and antecedent moisture conditions, while a flow-direction model integrated topography, land use, and stormwater drainage infrastructure in a GIS. The methodology developed and results generated will help stormwater planners visualise localised runoff and potentially adapt existing drainage networks to accommodate runoff, prevent flooding and erosion, and improve the stormwater quality entering nearby surfacewater bodies.     

INTEGRATED TEACHING AND PRACTICE: GREEN INFRASTRUCTURE PLANNING AND GREEN ROOF PERFORMANCE IN A SEMI-ARID CAMPUS ENVIRONMENT,USA

This paper presents an integrated education and research program that involves extensive participation from stakeholders on campus and beyond. The resultant water conscious design proposal promotes efficient stormwater management on Utah State University’s campus, situated in the semi-arid Intermountain West. Utah State has adopted various “green” solutions for stormwater management, such as directing most campus runoff to recharge groundwater. Yet, there is no comprehensive plan that lays out its sustainable practices, and little quantitative assessment of the design performance has been performed. In accord with the University Campus Master Plan of 2011 and Campus Sustainability Plan 2013-2020, this paper addresses this gap and proposes a series of green infrastructure strategies that make use of rain as a resource, and that can be implemented across campus in three phases. A built green roof project is part of the Phase I master plan. Pilot performance data are presented regarding stormwater runoff and temperature reduction on a green roof surface versus an adjacent test-bed asphalt roof. In summary, the paper provides a holistic approach toward adopting green infrastructure designs and assessing green infrastructure performance in the less evaluated semi-arid climatic conditions, and it serves as an example of research through design process.     

多尺度城市绿色雨水基础设施的规划实现途径探析

绿色雨水基础设施(GSI)具有重要的雨洪调蓄功能,是海绵城市建设的重要组成部分。总结国内在构建多尺度GSI过程中面临的挑战,提出GSI需结合城市绿地系统规划来实现。阐述了多尺度GSI的构成和功能,及其与海绵城市雨水系统的关系。从构成要素、功能、布局等方面,论述了GSI与绿地系统规划的关系,提出了两者在规划目标和指标、布局等方面的结合要点,包括对现行绿地系统规划指标的保留、新型指标的增添等。提出了新、旧城区绿地系统应分别以目标和问题为导向,根据城区绿地系统特点进行规划建设。提出了各类绿地GSI需结合其功能进行建设的要点。     

An optimal solution of thermal energy usage in the integrated system of stormwater collection and domestic-water heating

A solution is proposed to make use of the rainwater thermal energy in highly urbanised areas. It is demonstrated that the stormwater heat represents an additional on-site renewable energy available for hot water production. The proposed solution increases multi-functionality in the urban infrastructure that is essentially used to mitigate impacts from extreme climate events. The integrated system model applications correspond to local area conditions in the north-eastern Baltic region. This study considers the optimal collection of stormwater through maximizing the water absorbed heat usage in relation to hot water consumption in different building types (residential, public and commercial). Two key parameters, ‘stormwater volume in storage tank’ and ‘rainwater catchment area’, are determined. A genetic algorithm finds a number of storage tank fillings corresponding to rainfall statistics and the hot water consumption of buildings. System cumulative expenses are related to the stormwater storage and the rainwater harvesting expenses.     

Conventional and decentralized urban stormwater management: A comparison through case studies of Singapore and Berlin,Germany

Urban stormwater runoff is both a significant pollution source and a potentially valuable resource. This study compares stormwater management in two cities: Singapore and Berlin, Germany. In comparing the strategies for stormwater management, we illustrate how differences in geography (e.g., land and water availability), urban infrastructure, regulatory regimes, legislation and intensives between the two cities have led to different solutions for stormwater management. Singapore, faced with a serious issue of water scarcity, has placed an increasing emphasis on stormwater management through developing a comprehensive network of drains and canals, mainly with the aim of controlling flooding and potable water supply. In contrast, in Berlin, concerns for the protection of surface water quality and non-potable water supply in the urban areas have resulted in a shift in management goals towards a low impact solution based on source control. The cost analysis indicated that the decentralized rainwater harvesting as practiced in Berlin leads to a higher economic efficiency where potable water can be substituted by stormwater, compared to the centralized drainage system in Singapore. Additionally, green roofs result in energy savings by serving as mitigation strategies against the effect of urban heat islands and global warming. In the near future, it is envisioned that a combination of both conventional and decentralized urban stormwater management will prove to be the most practical solution for most cities.     

针对城市雨洪控制利用的不同目标合理设计调蓄设施

我国城市非点源污染、径流排放量增加、洪涝频繁等雨洪问题突出,传统的城市雨水排放设计理念已远远不能符合"绿色基础设施"理念的新型城市雨水系统的设计要求."调蓄"是城市雨洪控制利用系统中十分重要且广泛应用的一类措施,实践中需要根据项目的具体条件和雨洪控制利用系统的设计要求,针对控制径流污染、利用雨水、削减径流排放和控制洪涝等不同目标设计调蓄设施.介绍了调蓄的概念、设施的种类及其应用,据此分析说明了不同控制目标的调蓄设施设计原理及标准,为科学合理地设计城市雨洪控制利用系统及调蓄设施的设计提供参考.     

Developing the evidence base for mainstreaming adaptation of stormwater systems to climate change

In a context of high uncertainty about hydro-climatic variables, the development of updated methods for climate impact and adaptation assessment is as important, if not more important than the provision of improved climate change data. In this paper, we introduce a hybrid method to facilitate mainstreaming adaptation of stormwater systems to climate change: i.e., the Mainstreaming method. The Mainstreaming method starts with an analysis of adaptation tipping points (ATPs), which is effect-based. These are points of reference where the magnitude of climate change is such that acceptable technical, environmental, societal or economic standards may be compromised. It extends the ATP analysis to include aspects from a bottom-up approach. The extension concerns the analysis of adaptation opportunities in the stormwater system. The results from both analyses are then used in combination to identify and exploit Adaptation Mainstreaming Moments (AMMs). Use of this method will enhance the understanding of the adaptive potential of stormwater systems. We have applied the proposed hybrid method to the management of flood risk for an urban stormwater system in Dordrecht (the Netherlands). The main finding of this case study is that the application of the Mainstreaming method helps to increase the no-/low-regret character of adaptation for several reasons: it focuses the attention on the most urgent effects of climate change; it is expected to lead to potential cost reductions, since adaptation options can be integrated into infrastructure and building design at an early stage instead of being applied separately; it will lead to the development of area-specific responses, which could not have been developed on a higher scale level; it makes it possible to take account of local values and sensibilities, which contributes to increased public and political support for the adaptive strategies.     

Developing and testing a cost-effectiveness analysis to prioritize green infrastructure alternatives for climate change adaptation

Green infrastructure has been increasingly identified as an option to help manage climate change impacts in urban areas, although its implementation is still not widely promoted in urban planning. This is because of the lack of detailed analysis for decision-makers regarding construction and maintenance costs for different types and how effective various measures are at managing precipitation at a catchment scale. This paper contributes to fill this gap in knowledge by developing a green infrastructure cost-effectiveness ranking index (GICRI) able to evaluate the stormwater runoff volume reduction of multiple green infrastructure alternatives under different climate change scenarios, over differing spatial configurations and combining this performance data with their construction and maintenance costs. After applying this model over two case study areas, this paper provides three main insights. First, climate change projections have a significant impact on green infrastructure cost-effectiveness. Second, as green infrastructure cost-effectiveness is influenced by the spatial scale, there are different challenges for larger cities and smaller regional towns. Building on this, the paper argues that GICRI can be a simple and fast heuristic to increase the use of green infrastructure by informing decision-makers regarding how and where to prioritize investment or where greater modelling is needed.     

新西兰典型雨水管理政策剖析与启示

大力发展雨水利用事业，除技术支持以外，还需要完善的雨水利用制度和管理措施。介绍了新西兰雨水利用政策的整体框架及雨水管理政策，如雨水基础设施政策、私人地区雨水管理政策、雨水排放和处置政策、雨水灾害与地表径流政策、河流管理政策等。其次介绍了新西兰的雨水管理，主要包括洪水管理、河流管理、污染物管理等。在对新西兰雨水政策剖析的基础上，提出了对我国城市雨水管理的建议。     

Sustainable development and urban stormwater practice

The traditional use of piped systems for stormwater management is increasingly criticized as being ‘unsustainable’. These systems are part of the water domain where much research has focused on sustainable development indicators to support decision-makers in selecting systems that are more sustainable. However, the interest in sustainable development indicators is low. This paper identifies conditions to engage the practitioners to inform their actions in regard to sustainable stormwater management. Empirical evidence has been obtained from interviews with water professionals from Swedish municipalities. The environmental-technical discourse of sustainable stormwater development is a strong barrier in the change process, to the neglect of the social aspects. In the interviews, reframing the discourse was possible in visions of future sustainable stormwater systems embracing green infrastructure. In action, primary conditions can support sustainable pathways in realizing this vision. The paper suggests further incentives for increased implementation of non-structural measures by developing the identified conditions.     

An evaluation of the benefits of source control measures at the regional scale

Source control measures include rainwater tanks, infiltration trenches, grassed swales, detention basins and constructed wetlands that can be used in housing allotments and subdivisions. A methodology for evaluating the regional economic benefits due to implementation of source control measures is presented and illustrated for two case studies in the Lower Hunter and Central Coast regions of New South Wales, Australia. It is demonstrated that use of rainwater tanks to supplement mains water supply for toilet, hot water and outdoor uses can very significantly reduce demand on mains water supply. Reductions in regional water demand will enable deferment of water supply headworks augmentation, while reductions in peak mains water demand will extend the life of water supply distribution infrastructure. In addition, substantial reduction of stormwater discharge from allotments can be realised. For the Lower Hunter region with an urban population of about 450,000 it is shown that construction of new water supply headworks infrastructure can be delayed by up to 34 years. Compared with the traditional provision of mains water and stormwater disposal, the use of rainwater tanks along with other source control measures can produce present worth savings to the Lower Hunter region conservatively estimated to be up to $67 million. Similar results were found for the Central Coast region.     

灰绿雨水基础设施协同规划——美国山地 城市匹兹堡“绿色优先计划”之借鉴

山地洪涝灾害制约城市发展与安全。近年来,美国多处城市采取小规模且分散的绿色雨水基础设施(GSI)与传统管网系统相结合的方式来解决复杂的雨洪问题,发挥GSI的多种功能与效益。以美国山地城市匹兹堡的“绿色优先计划”为例,重点介绍了灰绿雨水基础设施在管理合流制溢流与洪涝等方面的效能评估方法,以及GSI融入排水分区城市设计框架的规划策略。以期在规划技术方法、多功能GSI、灰绿设施配置等方面为中国山地城市中灰绿雨水基础设施的协同规划提供参考。     

Identification of land use with water quality data in stormwater using a neural network

To control stormwater pollution effectively, development of innovative, land-use-related control strategies will be required. An approach that could differentiate land-use types from stormwater quality would be the first step to solving this problem. We propose a neural network approach to examine the relationship between stormwater water quality and various types of land use. The neural network model can be used to identify land-use types for future known and unknown cases. The neural model uses a Bayesian network and has 10 water quality input variables, four neurons in the hidden layer, and five land-use target variables (commercial, industrial, residential, transportation, and vacant). We obtained 92.3 percent of correct classification and 0.157 root-mean-squared error on test files. Based on the neural model, simulations were performed to predict the land-use type of a known data set, which was not used when developing the model. The simulation accurately described the behavior of the new data set. This study demonstrates that a neural network can be effectively used to produce land-use type classification with water quality data.     

Uncertainties in stormwater E. coli levels

Although water-quality monitoring programs have been widely used to identify and understand the level of pollution in urban stormwater systems, these data are often used without due consideration of the inherent uncertainties contained within these measurements. This study focuses on the uncertainties associated with the monitored levels of Escherichia coli, a common microbial indicator, in urban stormwater. Four sites located in Melbourne, Australia, were used to assess the uncertainty of six stormwater flow and E. coli variables: (1) discrete E. coli concentration, (2) stormwater flow rate, (3) stormwater event volume, (4) event mean concentration (EMC) of E. coli (i.e. a flow-weighted average of an event's E. coli concentrations), (5) E. coli load for each measured event, and (6) site mean E. coli concentration (SMC) (i.e. a volume-weighted average of the E. coli EMCs). Uncertainties of discrete E. coli samples were greater than 30%, while the uncertainty in stormwater flow measurements averaged greater than 97%, mainly due to the high uncertainties in measurements of very low flows. Propagation of these uncertainties, through their respective formulas, found that E. coli EMC uncertainties varied between 10% and 52% and that uncertainties relating to SMC estimates ranged from 35% to 55%. These results show the importance of considering uncertainty when using monitored data sets for any application, including those relating to stormwater management decisions. Suggestions are made about how to increase the accuracies of E. coli monitoring in urban stormwater and how to balance the different sources of uncertainties so that the overall combined uncertainties are minimised while keeping costs at a minimum.     

SAFL Baffle retrofit for suspended sediment removal in storm sewer sumps

Standard sumps (manholes) provide a location for pipe junctions and maintenance access in stormwater drainage systems. Standard sumps can also remove sand and silt particles from stormwater, but have a high propensity for washout of the collected sediment. With appropriate maintenance these sumps may qualify as a stormwater best management practice (BMP) device for the removal of suspended sediment from stormwater runoff. To decrease the maintenance frequency and prevent standard sumps from becoming a source of suspended sediment under high flow conditions, a porous baffle, named the SAFL Baffle, has been designed and tested as a retrofit to the sump. Multiple configurations with varying percent open area and different angles of attack were evaluated in scale models. An optimum configuration was then constructed at the prototype scale and evaluated for both removal efficiency and washout. Results obtained with the retrofit indicate that with the right baffle dimensions and porosity, sediment washout from the sump at high flow rates can be almost eliminated, and removal efficiency can be significantly increased at low flow rates. Removal efficiency and washout functions have been developed for standard sumps retrofitted with the SAFL Baffle. The results of this research provide a new, versatile stormwater treatment device and implemented new washout and removal efficiency testing procedures that will improve research and development of stormwater treatment devices.     

基于枚举算法的雨水管网优化设计

考虑到雨水管网的布置和计算特点,采用枚举算法进行雨水管网的优化设计。针对雨水管网内所有的干管和支管,该算法能够遍历雨水管道可选的标准管径集,找出符合约束条件的所有管径组合,然后利用造价函数筛选出管网造价最低的一种组合,并将其作为最终优化结果。利用Visual Basic 6.0语言编程并进行了工程应用,结果表明,枚举算法可以适用于复杂地形的雨水管网优化,是非常实用的全局优化方法。     

Infrastructure and institutions: Stakeholder perspectives of stormwater governance in Chicago

This article examines the ways stakeholder preferences and perspectives of stormwater management converge and diverge in Chicago. With a greater emphasis on broad stakeholder participation in urban environmental governance and decision-making, accommodating and moderating multiple and competing perspectives will become a greater part of urban green-space planning. Decision-makers must choose how resources are to be allocated to manage stormwater and decide among the multiple and sometimes conflicting options available to reduce the impact of stormwater at different sites across the city and region. This paper examines the disparate understandings of how to best manage stormwater in the city. The results reveal that departmental silos may not adequately explain variation in stakeholder perspectives. Instead, two dominant perspectives towards stormwater management connect diverse stakeholder groups in Chicago: the Infrastructural Interventionist and the Institutional Interventionist. The first strongly views stricter laws and regulations, developed in tandem with science and data-driven approaches, as the best way to improve stormwater management. The second desires new rules and institutions to foster integrated management approaches, as well as more robust economic instruments capable of assigning a monetary value to stormwater, as critical to resolving stormwater problems. Conflicting points of perspective arise around the preferred type of infrastructure to be implemented to deal with stormwater and how it is to be developed. Understanding how these two social perspectives interact and conflict is important in considering the actions that will ultimately be undertaken to direct landscape changes capable of resolving the multiple challenges Chicago faces in managing stormwater.     

绿色基础设施城市主义和气候变化

气候变化产生的环境影响：雨水污染加剧、城市洪水、海平面上升和城市热岛效应，已成为全球性问题。绿色基础设施（GI）越来越多地被推广为解决气候变化导致的环境恶化的“灵丹妙药”，尤其是在城市地区。城市本质上为高密度且不透水的空间，仅有少量的绿地来吸收预计增加的降雨量。位于沿海地区的城市容易受到海平面上升的影响，同时，大量的硬质表面会使空气温度的上升加剧。研究认为：可以利用绿色基础设施来改变当前的城市形态以构建应对环境影响的生态韧性。为了实现这一概念，必须将城市视为区域景观的一部分。采用一种基于流域的方法来探索如何用绿色基础设施改善气候变化对环境的影响，并使用推测性案例研究来证明这种方法，表明重新设计的城市形态可以优先安排绿色基础设施，而不会影响建筑项目和房地产投资回报。虽然该研究位于新西兰，但基于流域的方法也适用于中国的城市。     

Dominant perspectives and the shape of urban stormwater futures

Cognitive mapping is used to elicit perspectives on stormwater problems and solutions in West Auckland, New Zealand. In-depth interviews with key stakeholders reveal three dominant perspectives that underlie contemporary approaches to stormwater management: conventional fixes, low impact solutions and community development. Analysis confirms that these perspectives are diverse and partially conflicting. Traditional engineering approaches to managing urban stormwater generate feedback loops that necessitate continued construction of infrastructure to the detriment of environmental systems. Low impact solutions are environmentally sensitive, but they do not break this feedback loop. Community development could reduce the need for more urban stormwater infrastructure in the long-term but it does not address current adverse impacts of urban growth. Analysis suggests that none of the perspectives in themselves will lead to sustainable outcomes. Rather, the transition to a water-sensitive future requires understanding of and engagement with these diverse perspectives in efforts to establish more integrated social-ecological outcomes.     

Advancing assessment and design of stormwater monitoring programs using a self-organizing map: characterization of trace metal concentration profiles in stormwater runoff

Stormwater runoff poses a great challenge to the scientific assessment of the effects of diffuse pollution sources on receiving waters. In this study, a self-organizing map (SOM), a research tool for analyzing specific patterns in a large array of data, was applied to the monitoring data obtained from a stormwater monitoring survey to acquire new insights into stream water quality profiles under different rainfall conditions. The components of the input data vectors used by the SOM included concentrations of 10 metal elements, river discharge, and rainfall amount which were collected at the inlet and endpoint of an urban segment of the Yeongsan River, Korea. From the study, it was found that the SOM displayed significant variability in trace metal concentrations for different monitoring sites and rainfall events, with a greater impact of stormwater runoff on stream water quality at the upstream site than at the downstream site, except under low rainfall conditions (≤4 mm). In addition, the SOM clearly determined the water quality characteristics for “non-storm” and “storm” data, where the parameters nickel and arsenic and the parameters chromium, cadmium, and lead played an important role in reflecting the spatial and temporal water quality, respectively. When the SOM was used to examine the efficacy of stormwater quality monitoring programs, between 34 and 64% of the sample size in the current data set was shown to be sufficient for estimating the stormwater pollutant loads. The observed errors were small, generally being below 10, 6, and 20% for load estimation, map resolution, and clustering accuracy, respectively. Thus, the method recommended may be used to minimize monitoring costs if both the efficiency and accuracy are further determined by examining a large existing data set.