Urban Stormwater Infrastructure Research Articles

Occurrence of dissolved organic matter in storm-drain inlet sediments and its implication for urban stormwater infrastructure sustainability

In the context of climate change, the effective management of carbon in urban stormwater infrastructure (USI) become increasingly crucial. Research indicates that dissolved organic matter (DOM) plays a significant role in the carbon cycle within USI. However, there is a lack of comprehensive information regarding the occurrence of DOM in urban storm-drain inlet (SDI) sediments. This study was undertaken to examine the land use type-related distribution of DOM in SDI sediments, and then provide the suggestion for urban infrastructure sustainability. There are three findings: (1) The characteristics of DOM in SDI sediments, including content, hydrophilicity, molecular weight, and functional groups of aromatic rings, exhibited variation with land functional type; (2) Urban SDI DOM had low humification, and was primarily originated from autochthonous sources, with the proportion of humic-like components close to or exceeding 50%; and (3) SDI sediment DOM was likely to have different characteristics from road dust and stormwater due to microbial activities over dry season. Based on these findings, measures for urban stormwater infrastructure sustainability are proposed, including properly road sweeping, frequently SDI sediment dredging, decreasing in emission from industrial activities, promoting local educational practices, and limiting improper organic waste disposal. These results have implications for the management of stormwater-related carbon and provide valuable insights for the development of sustainable practices for urban ecosystems.

Policy, Institutions and Regulation in Stormwater Management: A Hybrid Literature Review

Policies, Institutions and Regulation (PIR) aspects matter for different sectors’ growth and inclusive sustainable development, but there is little information in the literature on how to evaluate the effects of PIR on management options and outcomes or, on how positive results PIR changes can bring. In terms of stormwater management systems, or urban drainage, PIR is also a controversial and absent matter. Multidisciplinarity, several actors, countless formal and informal rules, and strong contextual path dependence make the subject complex and intricate. Considering the enabling environment, an alignment between policies, institutions and regulations is required to achieve good results and provide sustainable services. This study conducted a hybrid literature review of peer-reviewed papers in this field to provide an overview of how researchers have been studying PIR relations. The gaps show that the understanding of the PIR is fragile, as an important element for analyzing of results to be achieved, including SDG6, the financing and obtaining funds, guarantees and grants for the execution, delivery, operation and maintenance urban stormwater services and infrastructure. The contribution of this review is not only about what exists, but also mainly about what does not exist, since the void keeps waiting to be filled.

The economic impacts of green stormwater infrastructure: An evaluation of novel stormwater management policies in Washington, D.C.

Increases in urban stormwater infrastructure needs have led cities around the world to turn towards nature-based ‘green’ stormwater infrastructure (GI). While GI can be an effective tool for addressing many urban flooding and water quality problems, many policymakers remain skeptical of GI due to concerns about financial uncertainties and performance risks. Moreover, cost-benefit analyses of changes to urban infrastructure policies often fail to consider the economic impacts – jobs created and value added to the regional economy – of infrastructure (traditional or GI) construction. Compounding this, few studies have modeled the economic impacts of GI. In this paper, we analyze the economic impacts arising from novel development regulations requiring GI to offset impervious cover expansion in Washington, D.C (USA). Using data from a survey of GI construction firms, we determine annual, direct GI investment, and construct an input-output model to estimate indirect and induced economic impacts at the regional scale. We find that, from 2015 to 2020, GI construction supported over $91 million in average annual economic output, ∼$45 million in labor income, ∼$60 million in value added, and created (or supported) 437 jobs in the DC metropolitan region. Sensitivity analysis around regulatory stringency (higher or lower stormwater retention requirements) reveals asymmetric economic impacts that increase more given higher retention requirements than they decrease for lower retention requirements. Our analytical approach can serve as a model to help other regions produce a more comprehensive accounting of the economic feasibility of green infrastructure for urban stormwater management.

Performance assessment for the integrated green-gray-blue infrastructure under extreme rainfall scenarios

Synergistic allocation of urban stormwater infrastructure is critical to flood risk prevention and control under extreme rainfall events. This study focuses on the interaction regularity of green, gray, and blue infrastructure in the process of runoff retention and discharge under extreme rainfall scenarios. Three strategies, namely, gray infrastructure, green-gray infrastructure, and green-gray-blue infrastructure, are proposed to analyze the effectiveness of different scenarios on flood risk control capabilities of urban drainage systems and to determine the key influencing factors of the three strategies. The results show that green-gray-blue infrastructure demonstrates synergy in improving the efficiency of urban drainage systems. Under gravity drainage conditions, the backwater jacking caused by high river water levels has a certain impact on the smooth discharge of stormwater runoff in urban drainage systems. This case study identified a sensitive range in the influence of water level on runoff control and drainage function and an adaptive range in which the flood increases slightly with the water level increase. These present notable rules in improving the synergistic effect of blue infrastructure in the integrated urban green-gray-blue infrastructure system.

Examining the Microclimate Pattern and Related Spatial Perception of the Urban Stormwater Management Landscape: The Case of Rain Gardens

This study examines the microclimate pattern and related spatial perception of urban green stormwater infrastructure (GSI) and the stormwater management landscape, using rain gardens as a case study. It investigates the relationship between different rain garden design factors, such as scale, depth, and planting design, and their effects on microclimate patterns and human spatial perception. Taking an area in Blacksburg, Virginia, as the study site, twelve rain garden design scenarios are generated by combining different design factors. The potential air temperature, relative humidity, and wind speed/direction are analyzed through computational simulation. Additionally, feelings of comfort, the visual beauty of the landscape, and the overall favorite are used as an evaluation index to investigate people’s perception of various rain garden design options. The study found that a multilayer and complex planting design can add more areas with moderate temperature and higher humidity. It also significantly improves people’s subjective perception of a rain garden. Furthermore, a larger scale rain garden can make people feel more comfortable and improve the visual beauty of the landscape, highlighting the importance of designing larger and recreational bioretention cells in GSI systems. Regarding depth, a relatively flatter rain garden with a complex planting design can bring stronger air flow and achieve better visual comfort and visual beauty. Overall, by examining the microclimate pattern and related perception of rain gardens, this study provides insight into better rain garden design strategies for the urban stormwater management landscape. It explores the potential of rain garden design in urban GSI and responds to climate change.

Challenges, drivers, and benefits to integrated infrastructure management of water, wastewater, stormwater and transportation systems

Infrastructure systems are known to be interdependent systems; however, infrastructure systems are typically managed individually by agencies in charge of these systems. The existing literature has proposed the concept of an integrated infrastructure management approach, yet this literature has focused on managing infrastructure systems in short-term contexts (e.g., response to natural and human-made disasters). As such, limited understanding exists about implementing an integrated infrastructure management approach in the long-term (i.e., maintenance and rehabilitation). This study aims to explore the challenges, drivers, and benefits of implementing an integrated urban infrastructure management approach by agencies managing urban water, wastewater, stormwater, and transportation infrastructure systems in the long-term. This study qualitatively analyzed 15 semi-structured interviews with stakeholders in the management of infrastructure systems in Chile. It was found that the implementation of an integrated infrastructure management approach is challenged and driven by organizational instead of technical aspects. It was found that the local context where agencies operate represents a challenge for the successful implementation, the willingness to collaborate of infrastructure agencies’ workers represents a driver to implementation, and that benefits encompass agencies and users. Infrastructure agencies can use our findings to account for contextual conditions to successfully implement an integrated infrastructure management approach.

Assessing the influence of urban greenness and green stormwater infrastructure on hydrology from satellite remote sensing

Green stormwater infrastructure (GSI), which includes features like rain gardens, constructed wetlands, or urban tree canopy, is now widely recognized as a means to reduce urban runoff impacts and meet municipal water quality permit requirements. Many co-benefits of GSI are related to increased vegetative cover, which can be measured with satellite imagery via spectral indices such as the Normalized Difference Vegetation Index (NDVI). In urban landscapes, there remain critical gaps in understanding how urban greenness and GSI influence hydrology. Here, we quantify these relationships to assess the feasibility of tracking the effectiveness of urban greening for improving downstream hydrologic conditions. We combined hydrologic data from the United States Geological Survey (USGS) gauges with an NDVI time series (1985–2019) derived from Landsat satellite imagery, and synthesis of GSI implementation data from a set of 372 urbanized watersheds across the United States. We used a multivariate panel modeling approach to account for spatial and time varying factors (rainfall, temperature, urban cover expansion) in an effort to isolate the relationships of interest. After accounting for expansion of urban boundaries, only 32 watersheds (9%) showed significant greenness trends, a majority of which were reductions. Urban greenness had significant influences on downstream flow responses, so that on average, a 10% greenness increase showed a corresponding reduction of total flow (−3.8%), flow variance (−7.7%), peak flows (−4.7%), high flows (−7.6%), flashiness (−2.2%), and high flow frequency (−1.5%); and a corresponding increase in baseflow (4.3%). For a subset of these watersheds for which GSI data were available (n = 48), the level of GSI implementation showed a significant, but weak influence on urban greenness with a 20% increase in BMP density corresponding to a greenness increase of 0.9%. The study results may support valuation and verification of GSI co-benefits in urbanized landscapes at the watershed scale.

A Bayesian Decision Model for Optimum Investment and Design of Low-Impact Development in Urban Stormwater Infrastructure and Management

Uncertainties concerning low-impact development (LID) practices over its service life are challenges in the adoption of LID. One strategy to deal with uncertainty is to provide an adaptive framework which could be used to support decision-makers in the latter decision on investments and designs dynamically. The authors propose a Bayesian-based decision-making framework and procedure for investing in LID practices as part of an urban stormwater management strategy. In this framework, the investment could be made at various stages of the service life of the LID, and performed with deliberate decision to invest more or suspend the investment, pending the needs and observed performance, resources available, anticipated climate changes, technological advancement, and users’ needs and expectations. Variance learning (VL) and mean-variance learning (MVL) models were included in this decision tool to support handling of uncertainty and adjusting investment plans to maximize the returns while minimizing the undesirable outcomes. The authors found that a risk-neutral investor tends to harbor greater expectations while bearing a higher level of risks than risk-averse investor in the VL model. Constructed wetlands which have a higher prior mean performance are more favorable during the initial stage of LID practices. Risk-averse decision-makers, however, could choose porous pavement with stable performance in the VL model and leverage on potential technological advancement in the MVL model.

Urban Pluvial Flood Management Part 2: Global Perceptions and Priorities in Urban Stormwater Adaptation Management and Policy Alternatives

Urban stormwater infrastructure is at an increased risk of being overwhelmed by pluvial flood events due to climate change. Currently, there are no global standards or frameworks for approaching urban rainfall adaptation policy. Such standards or frameworks would allow cities that have limited time, finances or research capacities to make more confident adaptation policy decisions based on a globally agreed theoretical basis. Additionally, while adaptation via blue-green infrastructure is often weighed against traditional grey infrastructure approaches, its choice must be considered within the context of additional policy alternatives involved in stormwater management. Using six global and developed cities, we explore to what extent a standardized hierarchy of urban rainfall adaptation techniques can be established through a combined Analytic Hierarchy Process (AHP) Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) Multi-Criteria Decision Analysis. While regional and stakeholder differences emerge, our study demonstrates that green infrastructure undertaken by public bodies are the top policy alternative across the cities and stakeholder groups, and that there exists some consensus on best management practice techniques for urban stormwater adaptation.

Three-Dimensional Numerical Modeling of Urban Green Stormwater Infrastructure Curb Inlets

AbstractThe current equations for curb inlet opening sizing often inaccurately estimate the capture efficiency of small urban green stormwater infrastructure (GSI) curb inlets. Most of these equati...

Engineering gentrification: urban redevelopment, sustainability policy, and green stormwater infrastructure in Minneapolis

ABSTRACT Cities increasingly turn to green stormwater infrastructure (GSI) to improve water quality and mitigate flooding risk, yet like other forms of green infrastructure, early research suggests GSI may contribute to ‘green gentrification,’ in which greening increases housing costs, drives gentrification and displacement, and deepens inequalities. Using a spatially explicit mixed-methods approach, I interrogate the relationship between GSI and gentrification in Minneapolis, MN, a city characterized by deep racial inequalities potentially exacerbated by green gentrification. From 2000-2015, census tracts that gentrified received, on average, more GSI projects, more funding per project, and more funding overall. Gentrified tracts received five times more GSI funding than low-income tracts that did not gentrify. Buffer analysis reveals that, adjacent to GSI, rent prices and the college-educated share of the population increased at rates significantly higher than the city average. Quantitative and qualitative analysis of institutions providing and receiving GSI funding indicates that inter-governmental collaborations between watershed governing bodies and city government direct GSI funding to gentrifying areas, where GSI aid in and legitimize the aesthetic transformation of gentrifying neighborhoods. When enmeshed in neighborhood recapitalization via green gentrification, GSI may ultimately deepen environmental inequalities, highlighting the need for planning and policies that proactively mitigate gentrification risks.

A planning-support tool for spatial suitability assessment of green urban stormwater infrastructure

Distributed green stormwater management infrastructure is increasingly applied worldwide to counter the negative impacts of urbanisation and climate change, while providing a range of benefits related to ecosystem services. They are known as Water Sensitive Urban Design (WSUD) in Australia, Nature Based Solutions (NBS) in Europe, Low Impact Development (LID) in the USA, and Sponge City systems in China. Urban planning for WSUD has been ad-hoc, lacking strategy and resulting in sub-optimal outcomes. The purpose of this study is to help improve strategic WSUD planning and placement through the development of a Planning Support System. This paper presents the development of Spatial Suitability ANalysis TOol (SSANTO), a rapid GIS-based Multi-Criteria Decision Analysis tool using a flexible mix of techniques to map suitability for WSUD assets across urban areas. SSANTO applies a novel WSUD suitability framework, which conceptualises spatial suitability for WSUD implementation from two perspectives: ‘Needs’ and ‘Opportunities’ for WSUD. It combines biophysical as well as socio-economic, planning and governance criteria (‘Opportunities’) with criteria relating to ecosystem services (‘Needs’). Testing SSANTO through comparing its results to work done by a WSUD consultancy successfully verified its algorithms and demonstrated its capability to reflect and potentially enhance the outcomes of planning processes. Manual GIS based suitability analysis is time and resource intensive. Through its rapid suitability analysis, SSANTO facilitates iterative spatial analysis for exploration of scenarios and stakeholder preferences. It thus facilitates collaborative planning and deeper understanding of the relationship between diverse and complex urban contexts and urban planning outcomes for WSUD.

Precipitation Extremes and Flood Frequency in a Changing Climate in Southeastern Virginia

AbstractDespite the advances in climate change modeling, extreme events pose a challenge to develop approaches that are relevant for urban stormwater infrastructure designs and best management practices. The study first investigates the statistical methods applied to the land‐based daily precipitation series acquired from the Global Historical Climatology Network‐Daily (GHCN‐D). Additional analysis was carried out on the simulated Multivariate Adaptive Constructed Analogs (MACA)‐based downscaled daily extreme precipitation of 15 General Circulation Models and Weather Research and Forecasting‐based hourly extreme precipitation of North American Regional Reanalysis to discern the return period of 24‐hr and 48‐hr events. We infer that the GHCN‐D and MACA‐based precipitation reveals increasing trends in annual and seasonal extreme daily precipitation. Both BCC‐CSM1‐1‐m and GFDL‐ESM2M models revealed that the magnitude and frequency of extreme precipitation events are projected to increase between 2016 and 2099. We conclude that the future scenarios show an increase in magnitudes of extreme precipitation up to three times across southeastern Virginia resulting in increased discharge rates at selected gauge locations. The depth‐duration‐frequency curve predicted an increase of 2–3 times in 24‐ and 48‐h precipitation intensity, higher peaks, and indicated an increase of up to 50% in flood magnitude in future scenarios.

Green Stormwater Infrastructure (GSI) for Stormwater Management in the City of Los Angeles: Avalon Green Alleys Network

Stormwater runoff creates flooding/pollution hazards in urban areas and Green Stormwater Infrastructure (GSI) provides modern technologies for prevention and mitigation. The Avalon Green Alley Network North and South GSI Demonstration Project (The GSIs) described in this article is a joint partnership between Los Angeles Sanitation (LASAN) and The Trust for Public Land (TPL). The GSIs is located in public alley right-of-way in a high-density neighborhood (residential, schools, parks, commercial building). The GSIs slows and infiltrates stormwater on site, capturing runoff from intersecting street catch basins, employing dry-well chambers, replacing impervious/conventional asphalt with permeable surfaces, percolating stormwater, and providing underground storage. The GSIs north section is closed to vehicular traffic after construction of a grassy swale to capture stormwater. Stormwater drains toward interlocking pavers and into underground infiltration trenches, with extra flows conveyed to a dry-well system. Monitoring includes groundwater monitoring wells, flow meters, and water-level loggers (measure water quality/quantity). Further benefits for the community includes of growing of vines/espalier trees, artistic paving, and mural artwork evoking artistic expression. The GSIs approach is setting a new trend for stormwater management in the City of Los Angeles in the untapped 1440 km of alleys, and serves as a model of community development through stormwater management to other cities.

Stochastic water balance dynamics of passive and controlled stormwater basins

Abstract Urbanization and changing rainfall intensities affect the performance of urban stormwater infrastructure, creating the necessity to design resilient stormwater systems. One proposed method to increase the resilience of stormwater infrastructure is the active control of system flows. To improve the understanding of actively-controlled urban water infrastructure function under variable hydro-climate, we develop a stochastic water balance model for stormwater retention and detention basins with both passive and actively-controlled outflow structures. Under active outflow control, the outflow valve is closed until the water level in the basin reaches a specified maximum at which point the valve opens and the basin empties. Using the stochastic water balance model, we develop analytical expressions for the steady-state probability density functions (PDFs) of water level and valve closure time, as well as the joint PDF of water level and valve closure time. These PDFs then are used to define water level and flow duration curves that provide a probabilistic description of the full range of basin performance. The model accurately predicts the water level PDF estimated from data collected at a retention basin with a passive outflow structure. The model provides a basis for evaluating how changes in the rainfall-runoff process, affected by land use and climate change, will impact the variability of stormwater basin water storage and pollutant removal function. We find that this variability can be managed through the adaptive updating of the active control rule for the outflow structure.

Risk analysis of urban stormwater infrastructure systems using fuzzy spatial multi-criteria decision making

Design and performance of stormwater infrastructure systems in urban areas have direct implications in social, environmental and public health problems and are of utmost importance to urban authorities and managers. Risk analysis in urban stormwater systems has become a must because of the extensive consequences of flooding in urban areas and limited funding for the rehabilitation and renovation of stormwater systems. Complexity, multidimensionality, and inherent uncertainties of the urban stormwater systems require the risk analysis approach to be comprehensive and able to address different uncertainties and spatial aspects of the problem. The objective of this study is to provide a comprehensive framework for risk analysis in urban stormwater systems. Multi Criteria Decision Making (MCDM), geographic information systems (GIS), and fuzzy sets theory are used to consider the diverse risk-affecting criteria, facilitate the analysis of spatial data and information and formulate the ambiguity and uncertainty of problem, respectively. The presented framework uses a Fuzzy Analytic Hierarchy Process (FAHP) for determining the weights of risk-affecting criteria (i.e. Hydrological and Hydraulic, Traffic, Social, Economic, Environmental, Structural, and Green space) in the presence of multiple decision makers. The Autodesk Storm and Sanitary Analysis model is used for the Hydrological and Hydraulic simulations. FSAW and FTOPSIS methods are used to provide the final product of the framework, i.e., a risk map that presents a risk level for each channel in the network. The framework is applied to District 11 of the capital city of Iran, Tehran as a real case study. The resulted risk maps indicate a high or very high flooding risk for 17.07 to 41.95 km of the stormwater channels in the study area, covering about 10.5 to 26% of the total length of the channels. The presented framework was found to be a suitable risk analysis tool in urban stormwater systems.

Assessing hydrological effects and performance of low impact development practices based on future scenarios modeling

Abstract Future scenarios modeling has been conducted to investigate the effectiveness of urban stormwater infrastructure and to cater to potential future changes. The changes of quantity and quality of urban stormwater, and attributable to climate change and urbanization, were examined and tested in four urban catchments based on future scenarios modeling. Based on our findings, we observed that there were different degrees of performance corresponding to 2-, 10-, and 100-year design storms. However, the general patterns and insights deduced were similar: (1) the peak runoff and water quality appeared to be impacted more significantly by urbanization factors than that due to climate change; (2) the influence from urbanization (increase intensity of land use and population density) was found to be more significant than that from land-use changes alone; (3) catchments with relatively rapid developing rates appeared to produce more serious adverse influence on the stormwater quabntity and quality; and (4) low impact developments as key adaptation practices could be potentially effective in mitigating adverse impacts of future changes on urban stormwater system. The methodology developed in this study could be useful for urban stormwater planning and testing the plan against future change scenarios as a result of urbanization and climate change.

Future Scenarios Modeling of Urban Stormwater Management Response to Impacts of Climate Change and Urbanization

Future scenarios modeling is used to investigate the effectiveness of the urban stormwater infrastructure and its response to potential future changes. The changes of urban stormwater, both in‐flow quantity and water quality, in response to climate change and urbanization are examined and tested in two highly developed urban catchments using the US Environmental Protection Agency's Storm Water Management Model. Similar responses are observed in the two catchments, despite their differences in size and land use. Flow quantity and water quality appears to be more sensitive to urbanization factors than to climatic change. With respect to factors attributable to urbanization, urban intensification (land use plus population density) has more of an effect than land‐use changes alone. Low‐impact development, as a key adaptation measure, could be effective in mitigating the adverse impacts of future changes on urban stormwater. The methodology developed in this study may be useful for urban stormwater planning and testing such plans against future urbanization and climate change scenarios.

Bivariate frequency analysis of rainfall intensity and duration for urban stormwater infrastructure design

This study presents a storm-event based bivariate frequency analysis approach to determine design rainfalls in which, the number, intensity and duration of actual rainstorm events were considered. To derive more realistic design storms, the occurrence probability of an individual rainstorm event was determined from the joint distribution of storm intensity and duration through a copula model. Hourly rainfall data were used at three climate stations respectively located in Singapore, South Korea and Canada. It was found that the proposed approach could give a more realistic description of rainfall characteristics of rainstorm events and design rainfalls. As results, the design rainfall quantities from actual rainstorm events at the three studied sites are consistently lower than those obtained from the conventional rainfall depth-duration-frequency (DDF) method, especially for short-duration storms (such as 1-h). It results from occurrence probabilities of each rainstorm event and a different angle for rainfall frequency analysis, and could offer an alternative way of describing extreme rainfall properties and potentially help improve the hydrologic design of stormwater management facilities in urban areas.

Zero increase in peak discharge for sustainable development

For urban land development, some or all natural land uses (primarily pervious) are converted into impervious areas which lead to increases of runoff volume and peak discharge. Most of the developed countries require a zero increase in peak discharge for any land development, and the policy has been implemented for several decades. The policy of zero increase in peak discharge can be considered as historical and early stage for the low impact development (LID) and sustainable development, which is to maintain natural hydrological conditions by storing a part or all of additional runoff due to the development on site. The paper will discuss the policy, the policy implementation for individual projects and their impact on regional hydrology. The design rainfalls for sizing LID facilities that are determined in 206 weather stations in USA are smaller than design rainfalls for sizing detention basins. The zero-increase policy links to financial responsibility and sustainability for construction of urban stormwater infrastructures and for reducing urban flooding. The policy was compared with current practices of urban development in China to shine the light for solving urban stormwater problems. The connections and differences among LID practices, the zero-increase policy, and the flood control infrastructure were discussed.We promote and advocate the zero-increase policy on peak discharge for comprehensive stormwater management in China in addition to LID.