Installation Of Green Infrastructure Research Articles

Scenario-Based Green Infrastructure Installations for Building Urban Stormwater Resilience—A Case Study of Fengxi New City, China

Global climate change has precipitated a surge in urban flooding challenges, prompting the imperative role of green infrastructure (GI) as the linchpin of sponge city construction to enhance urban sustainability and resilience. But the evaluation of urban stormwater resilience faces challenges due to the lack of a comprehensive evaluation framework taking the intrinsic features of the resilience system into account and the insufficient coverage of alternative scenarios’ performance under multiple rainfall return periods. This study, focusing on Fengxi New City, China, evaluates the suitability of GI (i.e., green roofs, rain gardens, and permeable pavements) and constructs a stormwater management model (SWMM) for urban stormwater hydrological simulation. This study also establishes a comprehensive urban stormwater resilience evaluation system and uses quantitative methods to unify the performances of scenarios under different rainfall return periods. Our analytical findings elucidate that the suitability of GI is predominantly concentrated in the northern and western areas of the study area, with the smallest suitable area observed for permeable pavements. Divergent GIs exhibit disparate performances, with rain gardens emerging as particularly efficacious. Importantly, the combination of multiple GIs yields a synergistic enhancement in resilience, underscoring the strategic advantage of adopting a diverse and integrated approach to GI implementation. This study facilitates a deeper understanding of urban stormwater resilience and assists in informed planning decisions for GI and sponge cities.

Interdisciplinary Perspectives on Green Infrastructure: A Systematic Exploration of Definitions and Their Origins

Green Infrastructure (GI) is rooted in ecology and cuts across multiple disciplines, including landscape architecture, environmental sciences, planning, policy, and engineering. Likewise, the definition of this concept also cuts across disciplines, which creates ambiguity around what GI is and what makes up GI in practice—for example, mistaking bioswales for regular tree planters or green space within communities in which they are installed. We undertook a systematic literature review of 38 peer-reviewed articles for this study using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method to identify and synthesize the different disciplinary definitions of GI in the literature. This study also presents the types of GI systems mentioned in the peer-reviewed articles while identifying other benefits apart from the primary benefit of GI installation, which is stormwater management. The analysis revealed three clusters of GI definitions: (I) Interconnected natural areas and other open spaces, (II) Strategically planned natural and semi-natural areas, and (III) Decentralized systems and techniques. However, we got rid of the third cluster during the analysis because GI is known to be a decentralized system, and the definition region could not be tracked. These clusters represent a spectrum, one of which employs the structure of natural systems already in place to support human goals (bio-inclusivity). The other includes living systems as components within engineered solutions to achieve objectives (bio-integration). This review points to the need for an encompassing definition that cuts across disciplines with a consensus on the adoption and concise categorization of GI types and the multiple benefits they provide to humans and ecosystems. A consensus definition helps clear misconceptions and improve the understanding of GI, potentially improving receptivity towards these solutions within communities from a community member perspective.

Public perception and preferences of industrial green infrastructure in Northwest China

The increasing global demand for sustainable urban development has led to the widespread adoption of Green Infrastructure (GI) worldwide. However, there remains a lack of understanding regarding public support for implementing GI specifically at industrial sites. This study focuses on promoting industrial GI (IGI) and examines residents' willingness to pay (WTP) for GI installation and the nonmarket value of GI is estimated using the travel cost method (TCM). Among respondents residing in neighborhoods surrounding industrial areas, a significant proportion (90%) expressed their WTP for GI promotion. The aggregated annual WTP for IGI and Neighbourhood GI (NGI) were estimated to be approximately CNY 16.2 million and CNY 21.9 million, respectively. Moreover, the annual nonmarket value provided by IGI and NGI to human well-being was estimated to be around CNY 4.5 million and CNY 20.7 million, respectively. The study reveals that middle-aged and middle-income groups exhibit a higher propensity for WTP, with specific GI measures such as rain gardens, vegetated swales, trees, and naturalized landscaping receiving greater WTP intentions. The primary challenges identified for promoting IGI include cost, policy, and maintenance considerations. This study recommends customizing planning approaches for IGI promotion, considering diverse demographics, including constructing youth apartments near industrial areas, implementing age-friendly design features, and enhancing landscape design in elderly communities. Disseminating GI knowledge through media and partnering with local organizations for awareness enhancement is essential for encouraging higher WTP. The effectiveness of water features and pedestrian-friendly areas in improving and promoting IGI spaces is also highlighted. These findings offer valuable insights to policymakers and city planners, facilitating the identification of more effective GI designs for promoting sustainable urban environments that align with societal preferences and demands.

Metal accumulation patterns in Pittsburgh, PA (United States) green infrastructure soils: road connections and legacy soil inputs

Aging water infrastructure renewal in urban areas creates opportunities to systematically implement green infrastructure (GI) systems. However, historical soil contamination from gasoline lead additives, steel manufacturing by-products, and other historical industry raise the potential that novel GI drainage patterns and geochemical environments may mobilize these legacy pollutants to green infrastructure sites previously isolated from most hydrologic flows. Characterization of GI soil chemistries across GI type to build on previous observations in other cites/regions is fundamental to accurate assessments of these emerging management scenarios and the resultant risk of increased metal exposures in downstream environments. In particular, clarification of ecosystem services this metal sequestration may provide are vital to comprehensive assessment of green infrastructure function. During 2021, soil metal chemistry, specifically, As, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn was measured at a high spatial resolution in six Pittsburgh (Pennsylvania, United States) GI installations using a portable X-ray Fluorescence Spectrometer. Patterns of trace metal accumulation were identified in these installations and evaluated as a function of site age and GI connection to road systems. Trace metals including chromium, copper, manganese, and zinc all seem to be accumulating at roadside edges. Remobilization of historically contaminated soils also seems to be a potential mechanism for transporting legacy trace metal contamination, particularly lead, into GI systems. However, metals were not clearly accumulating in installations less connected to road inputs. These findings are consistent with literature reports of trace metal transport to GI systems and reconfirm that clarification of these processes is fundamental to effective stormwater planning and management.

Optimal siting of rainwater harvesting systems for reducing combined sewer overflows at city scale

The installation of green infrastructure (GI) is an effective approach to manage urban stormwater and combined sewer overflow (CSO) by restoring pre-development conditions in urban areas. Research on simulation-optimization techniques to aid with GI planning decision-making is expanding. However, due to high computational expense, the simulation-optimization methods are often based on design storm events, and it is unclear how much different rainfall scenarios (i.e., design storm events vs. long-term historical rainfall data) impact the optimal siting of GI. The Parallel Pareto Archived Dynamically Dimensioned Search (ParaPADDS) algorithm in a novel simulation-optimization tool OSTRICH-SWMM was used to leverage distributed computing resources. A case study was conducted to optimally site rainwater harvesting cisterns within 897 potential subcatchments throughout the City of Buffalo, New York. Seven design storm events with different return periods and rainfall durations and a one-month historical rainfall time series were considered. The results showed that the optimal solutions of siting cisterns using event-based scenarios, though less computationally expensive, may not perform well under continuous rainfall scenarios, suggesting design rainfall scenarios should be carefully considered for optimizing GI planning. The impact of rainfall scenarios was particularly significant in the middle region of the Pareto front of multi-objective optimization. Utilizing high-performance parallel computing, OSTRICH-SWMM is a promising tool to optimize GI at large spatial and temporal scales.

Effects of watershed-scale green infrastructure retrofits on urban stormwater quality: A paired watershed study to quantify nutrient and sediment removal

Urban stormwater represents a substantial source of nutrients and sediment to aquatic ecosystems. Green infrastructure (GI), including bioretention and permeable pavement, is an increasingly utilized method to treat stormwater pollutants. Using soil and plants as natural filters, these systems are effective at the site scale, but little evidence exists regarding their performance at the watershed-scale. Blueprint Columbus is an effort by the City of Columbus, Ohio, USA to retrofit GI to eliminate sanitary sewer overflows and remove 20% of total suspended solids (TSS) from existing developed areas. Changes in water quality resulting from the combined effects of many GI practices installed in 11.5 and 47.8 ha treatment watersheds were quantified using a paired-watershed approach. Based on water quality data collected by automated samplers over a 3.5-year period, significant reductions in particulate and dissolved nutrients as well as sediment were observed following the installation of GI in both treatment watersheds compared to the control. Total nitrogen (TN), phosphorus (TP), and TSS concentrations decreased by 13.7–24.1%, 20.9–47.4%, and 61.6–67.7%, respectively. Runoff attenuation by GI contributed to pollutant load reductions of 24.0–25.4% (TN), 27.8–32.6% (TP), and 59.5–78.3% (TSS). Orthophosphate concentrations and loads increased in the watershed with bioretention only but significantly decreased in the treatment watershed with bioretention and permeable pavement. Reductions in TSS concentration were similar (within a margin of 5%) to the percent of the watershed imperviousness treated by GI. Results demonstrate that GI was effective in reducing runoff event mean concentrations and loads at the watershed-scale.

Urban flood risk and green infrastructure: Who is exposed to risk and who benefits from investment? A case study of three U.S. Cities

Pluvial flooding is a serious hazard in inland U.S. cities. City managers and communities are increasingly interested in reducing their pluvial flood risk through the development of green infrastructure (GI) features. This research explores the relationship between pluvial flood exposure and GI placement in three inland cities–Atlanta, Phoenix, and Portland–and analyzes the variation of sociodemographic variables in census block groups (CBG) located in pluvial flood zones. Using the Arc-Malstrøm method, we estimated areas of pluvial flooding in the CBGs of our selected cities by relating pluvial flood area to the density of GI in CBGs and assigning CBGs one of four classifications: i) managed (large flood area, abundant GI), ii) prepared (small flood area, abundant GI), iii) vulnerable (large flood area, scarce GI), and iv) least concern (small flood area, scarce GI). Then, using the historical GI data, we examined the proportionality of GI investment over time to pluvial flood area. We found relationships between GI density, flood area, ethnic and racial minority populations, age, educational attainment, and median household incomes that indicated inequalities and potential discrimination in flood risk management, but also some evidence of equitable and appropriate management given differences in flood risk, especially in Phoenix and Portland. In Atlanta, newer GI installation prioritized white and wealthy neighborhoods where relatively higher flood risk exists (less equitable). Our classification framework may assist city flood risk managers to distribute GI more equitably according to equitability and need.

Spatial design strategies and performance of porous pavements for reducing combined sewer overflows

The installation of Green Infrastructure (GI) is a popular strategy for reducing stormwater runoff that contributes to Combined Sewer Overflows (CSOs). However, quantifying the impact of proposed GI systems on CSO discharges is a difficult task that requires the simulation of runoff in a complex network of land parcels, drainage controls, and sewer pipes. In this study, the performance of Porous Pavement (PP) was examined, with a focus on how the spatial design of PP features affects predicted CSO volume. Numerical experiments were performed to explore how simulation-based designs can identify specific subcatchments for cost-effective PP implementation subject to budgetary constraints. Among the alternative design strategies considered, simulation–optimization was effective at finding cost-effective solutions. The experiments showed that PP can achieve substantial CSO reductions across a range of rainfalls, budgets, and CSO drainage characteristics, but the performance is sensitive to the spatial configuration of the features. Good-performing systems were also identified by generating multiple realizations via a randomized clustering strategy, with additional improvement provided by the more computationally expensive optimization process.

Regenerative Green Infrastructure Governance in Weak, Rebounding, and Wealthy Land Markets

Too often scholars valorize green infrastructure without critically examining the dynamic and multi-faceted ways that greening impacts urban environments. Cities are complex, evolving forces of their own, which grow and shrink according to time and place. Governance strategies in different economic conditions powerfully shape the impacts of specific green infrastructure installations. They determine the value, quality, quantity, and spatial arrangement of green infrastructure. However, most scholarship focuses on the psychological, social, economic, and environmental benefits of urban greening. Green infrastructure is overwhelmingly studied as apart from historical urban governance trajectories, and it largely fails to consider the role of greening within the process of urban regeneration. This disconnect constitutes a significant gap that constrains understanding of green infrastructure for regenerative cities, and it limits our ability to strategically deploy it in beneficial rather than harmful or irrelevant ways. In this article, I argue that green infrastructure lays fundamentally different roles in poor and wealthy parts of cities, and that these roles change as the overall rank and status of the cities change over time. These changing meanings cause city governments to treat green infrastructure as fundamentally different targets of management. These conclusions are based on an ethnography of the public policy processes surrounding urban greening in three cities with different land markets. In the strong land market, the emphasis is placed firmly on revenue-generating projects, and the major players are private firms in conjunction with city departments. Greening is conceived as a byproduct of large-scale development projects, and rarely apart from them. In the weak land market city, in contrast, the environmental and civic organizations play major roles, and they conceive of green infrastructure apart from development projects. Weak land markets seem to create the possibility for increased political participation of environmental actors and for the installation of green infrastructure for the primary purpose of community health and well-being. However, the increased strength of environmental civic coalitions appears negatively correlated with the city's economic capacity to fund greening projects without support from the business community. These dynamics suggest a counter-cyclical relationship between the political will for urban greening and the investment capacity to pay for it. The analysis of green infrastructure in different land markets demonstrates that green infrastructure is deeply embedded in the historical and geographical legacies of cities.

Effects of low impact development on the stormwater runoff and pollution control

The frequent urbanization and extreme rainfall events have posed the threat to the urban environment. The implementation of low impact development (LID) practices with great potential for control urban flood and overflow pollution is not comprehensively understood yet due to the influence of complex factors (i.e., hydrological pattern, installation location, and vertical parameter setting). In this study, the hydraulic and water quality model were used to analyze the hydrological and pollution reduction of outfall and storage under different hydrological patterns, vertical parameter setting, and green infrastructure installation locations, which can determine the best implementation of the scheme for overflow pollution control. The results showed that nine parameters of the vertical layer regarding the four parameters impacted the peak value and load of suspended solids (SS). The combination scheme of the LID practices was further proposed based on the selection and analysis of the single LID practice. Besides, considering the installation location, the downstream installed location was a better choice. The horizontal connection of overflow runoff and pollution could be reduced by up to 9.75% and 36.46%, respectively. In addition, the horizontal connection can effectively reduce the peak value of inflow and pollutants at the time of assessing storage tank impact, which reach the maximum of 14.08% and 29.25%, respectively. The pollutants distribution became uniform and showed better resilience against rainfall intensity, which is beneficial to the management of stormwater. Our findings can provide guidance for Sponge City construction and effectively alleviate the combined sewer overflow.

The Impacts of Climate Change and Porous Pavements on Combined Sewer Overflows: A Case Study of the City of Buffalo, New York, USA

Combined sewer overflows (CSOs) release pollutants collected in urban runoff into local waterways, impacting both aquatic life and human health. The impact of climate change on precipitation may result in an increase in the frequency and magnitude of heavy precipitation events, with a corresponding increase in CSO discharges. The installation of Green Infrastructure (GI) such as Porous Pavements (PP) is a resilient approach to mitigate CSO events. However, an understanding of the impact of climate change on CSO events and the effectiveness of GI practices is crucial for designing sustainable urban stormwater management systems. Using the Storm Water Management Model (SWMM), the performance of PP as a CSO abatement strategy was studied for the city of Buffalo, New York, USA. This paper used the Intensity-Duration-Frequency (IDF) curves for current (1970–1999) and future (2070–2099) design rainfall scenarios, with four rainfall durations (1, 6, 12, and 24 hours) and four return periods (2, 10, 50, and 100 years). The simulation results show that (1) current 100-year events generate CSO volumes similar to predicted 50-year events; (2) CSO volumes could increase by 11–73% in 2070–2099 compared to 1970–1999 when no GI intervention is performed; and (3) the installation of PP can reduce 2–31% of future CSO volume. This case study demonstrates the regional CSO challenges posed by climate change and supports the use of GI as a mitigation strategy.

Resident Knowledge of and Engagement with Green Infrastructure in Toronto and Philadelphia

Green infrastructure (GI) initiatives, including programs to plant trees and install bioswales, have been adopted by a growing number of local government and non-governmental organizations. While the details of these programs vary, a common characteristic of most Canadian and US GI initiatives is a distributed approach that includes both public and private land. To date, little research has explored residents' knowledge of GI or their engagement with related initiatives even though residents' installation of GI is often key to creating distributed GI networks. In this study, we (1) assess residents' knowledge of the term GI, (2) identify residents' level of engagement with GI initiatives, and (3) examine whether factors like level of concern about local environmental issues can predict GI knowledge or level of engagement with GI initiatives. We explored these objectives through a survey of residents in Toronto (Ontario, Canada) and Philadelphia (Pennsylvania, US). We found that about a quarter of survey respondents in both cities had previously heard the term "green infrastructure". Neither knowledge of GI nor level of engagement with GI initiatives could be predicted by the level of concern about local environmental issues, but residents' interest in using their outdoor space for nature activities (e.g., gardening) predicted GI knowledge in both cities and level of initiative engagement in Philadelphia. Our results suggest the need for widespread education campaigns that clearly define GI so that residents can be participants in policy discussions, link it with their needs, and identify ways to manage GI to create desired benefits.

Impact of green infrastructure on the mitigation of road-deposited sediment induced stormwater pollution

As a vital stormwater pollution source, the pollutants associated with road-deposited sediment (RDS) have become a growing concern in urban water management. Green infrastructure has exhibited great potential in stormwater pollution mitigation, but is not comprehensively understood yet due to the influences of complex RDS-associated pollutant migration processes (i.e., build-up, wash-off, and discharge). In this study, a city-scale hydraulic and water quality model was used to analyze the migration and removal processes of four RDS-associated pollutants (total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP)) under different hydrological patterns, land-cover types, and green infrastructure installation locations. Results show that the antecedent dry-weather period was the main factor influencing RDS build-up, while the precipitation pattern strongly impacted RDS wash-off, discharge, and removal. The downstream-installed green infrastructures reduced the RDS-induced stormwater pollution by up to 68% and relieved the pollution-mitigation pressure of the studied drainage networks by almost 50%. The TSS and COD removal rates were higher (62.22–68.09%) near green space, while those of TN and TP were higher around buildings and roads (40.00–62.50%). Sensitivity analysis indicated that seven parameters regarding the surface layer characteristics and soil texture class strongly impacted the pollution-mitigation performance among the 31 technical parameters of green infrastructure. The results of this study would assist urban water management by optimizing green infrastructure for stormwater pollution mitigation.

Users’ Perceptions of Green Roofs and Green Walls: An Analysis of Youth Hostels in Lisbon, Portugal

Green roofs and green walls are a potential strategy to increase green spaces in the urban environment. These solutions bring multiple benefits to the cities at the economic and socio-environmental levels. However, from the point of view of private investors, green roofs and green walls often have a negative financial evaluation. Concerning this, the quantification of the benefits according to building use and occupancy could be an important tool to assist the decision-making process and guarantee returns on investment. This study aims to support the decision-making process by managers and owners of youth hostels regarding green roofs and green walls implementation. Using a structured questionnaire, users’ perceptions were assessed through a five-point Likert scale. The survey was conducted in five youth hostels in Lisbon, Portugal. Analyses were performed in two phases. Firstly, using the original sample (n = 345), and subsequently grouping homogeneous individuals through cluster analysis. The results showed that most respondents support green infrastructure installation in the hostel and consider that these solutions could provide a greater sense of individual well-being and local aesthetic improvement. However, there is no strong evidence that green infrastructure solutions are considered a deciding factor to select local lodging, despite the fact that it can be a tiebreaker factor between two similar options. Furthermore, findings have shown that 90% of the respondents from Cluster 1 and 92% from Cluster 4 are probably not willing to pay higher daily rates for youth hostels that have green infrastructure solutions in place. On the other hand, 67% of the respondents from Cluster 2 were potentially willing to pay an additional amount. For the 345 respondents, the most preferred green infrastructure typologies are indoor living wall and the accessible green roof. Moreover, findings support the gender socialization and identity theory showing that women have a greater environmental concern compared to men.

Assessment of green infrastructure performance through an urban resilience lens

Green infrastructure (GI) is widely recognized for reducing risk of flooding, improving water quality, and harvesting stormwater for potential future use. GI can be an important part of a strategy used in urban planning to enhance sustainable development and urban resilience. However, existing literature lacks a comprehensive assessment framework to evaluate GI performance in terms of promoting ecosystem functions and services for social-ecological system resilience. We propose a robust indicator set consisting of quantitative and qualitative measurements for a scenario-based planning support system to assess the capacity of urban resilience. Green Infrastructure in Urban Resilience Planning Support System (GIUR-PSS) supports decision-making for GI planning through scenario comparisons with the urban resilience capacity index. To demonstrate GIUR-PSS, we developed five scenarios for the Congress Run sub-watershed (Mill Creek watershed, Ohio, USA) to test common types of GI (rain barrels, rain gardens, detention basins, porous pavement, and open space). Results show the open space scenario achieves the overall highest performance (GI Urban Resilience Index = 4.27/5). To implement the open space scenario in our urban demonstration site, suitable vacant lots could be converted to greenspace (e.g., forest, detention basins, and low-impact recreation areas). GIUR-PSS is easy to replicate, customize, and apply to cities of different sizes to assess environmental, economic, and social benefits provided by different types of GI installations.

Green infrastructure site selection in the Walnut Creek wetland community: A case study from southeast Raleigh, North Carolina

Recent findings have shown that minority communities are frequently underserved by green infrastructure developments relative to non-minority communities, as local installations of green infrastructure often follow patterns of gentrification. Antipathy from these communities toward existing environmental management efforts present further obstacles related to green infrastructure placement. While hydrologic modeling has been highly utilized in decision support for green infrastructure placement, this technique does not consider ownership, access concerns, or the importance of visibility. Alternatively, participatory geographic information systems (PPGIS) can provide a different perspective from hydrologic models, as they have the potential to forecast community perceptions of green infrastructure utility, rather than hydrological benefit. We use a mixed-methods approach to optimize green infrastructure site-selection that considers hydrologic vulnerabilities in the context of place-based knowledge and historical realities. Residents’ perceptions of the locations of nuisance flooding were reported via participatory mapping within a paper-based survey (n = 95) conducted in the communities surrounding Walnut Creek, a historically African-American community in Raleigh, North Carolina. Hotspot analysis was used to identify statistically significant clustering, which was related to a correspondence between participant-indicated nuisance flooding sites and high flow accumulation cells. Comparison of the participatory and hydrologic hotspot analyses show some geospatial overlap for potential green infrastructure placement. We propose that, when undertaken with community input, green infrastructure installation in these downstream areas may help offset localized flooding patterns while facilitating greater trust with stormwater and environmental practitioners.

A runoff trading system to meet watershed-level stormwater reduction goals with parcel-level green infrastructure installation

Green infrastructure (GI) has been recommended widely to reduce runoff from the built environment. However, reliance on public land for GI implementation could cause a heavy financial burden on local governments. Although economic incentives and market-based mechanisms may encourage public participation in managing stormwater by installing GI on private parcels, a runoff trading market has not been fully developed in practice. To establish a market, in part, requires a watershed-based planning framework and fully informed parcel owners in regard to tradable credits, costs, and benefits. We propose a scenario-based Stormwater Management Planning Support System for Trading Runoff Abatement Credits (SMPSS-TRAC) to facilitate the calculation and allocation of stormwater runoff abatement credits in order to assist the decision-making of GI investment. We apply SMPSS-TRAC to a watershed located in Hamilton County, Ohio, USA and develop five scenarios representing increasing use of GI. We test the scenarios under a 5-year rainfall intensity and set a cap of runoff for each scenario at a level that is equal to the runoff from an undeveloped status (1.03-inch runoff depth for the watershed). With the proposed SMPSS-TRAC, the watershed authority could encourage all parcel owners to install suitable GI or purchase credits from the market. When detention basins are needed to meet a stated goal, the watershed authority would build them on vacant lots and share costs with all parcels within the same sub-catchment. The last scenario with four types of GI installed, shows that the watershed reaches market equilibrium and generates 15,358 m3 credit surplus. SMPSS-TRAC has the potential for including multiple stakeholders' preferences and concerns in searching for preferable scenarios.

Evaluating the effects of canine urine on urban soil microbial communities

Due to extensive areas of impermeable surfaces, combined sewer overflow (CSO) is currently a major problem in urban areas across the United States. In CSO systems, sewage can travel through underground pipes to be decontaminated in treatment facilities, or it can combine with stormwater after a precipitation event and discharge into local waterways. Many cities are implementing green infrastructure installations, which use vegetation and bioactive soil microbial communities to enhance soil water-holding capacity, thereby minimizing CSO events. Understanding the factors that structure soil microbial communities in green infrastructure will facilitate more effective management of these engineered ecosystems; however, few studies to date have evaluated ecological patterns and processes of microbes in the urban environment. Nitrogen loading is known to be a major factor structuring fungi and bacteria in non-urban soils, and since cities also contain large populations of canines, N-rich urine deposition is a potential factor that could be important for structuring soil microbes in ground-level green infrastructure installations. Our study investigated the effects of canine urine on the urban soil microbial communities in a greenhouse experiment by treating Liriope muscari, a common plant found in New York City green infrastructure, with different concentrations of canine urine for 4 weeks in an experimental setting. We found that urine application significantly decreased total soil microbial biomass and microbial richness, and increased water runoff volume. These findings indicate that canine urine may have negative consequences for soil water-holding capacity and nutrient cycling in urban green infrastructure installations by directly decreasing the abundance and richness of soil microbial communities.

OSTRICH-SWMM: A new multi-objective optimization tool for green infrastructure planning with SWMM

The installation of Green Infrastructure (GI) can revitalize communities while reducing sewage overflows and improving runoff quality. However, determining the proper GI investment is a challenging management task. Numerical hydrologic models, such as the Storm Water Management Model (SWMM), are the primary design tool for GI. A new open-source multi-objective SWMM optimization tool was developed by connecting SWMM with the existing Optimization Software Toolkit for Research Involving Computational Heuristics (OSTRICH). In contrast to similar tools, it is open-source and has a large selection of parallelized algorithms. A case study of stormwater management in Buffalo, New York, demonstrated how the tool can illuminate trade-offs between the cost of rain barrel placement and the resulting reduction in combined sewer overflows. In the future, this tool could be used to optimize different types of GI features and contribute to a broader decision support framework for urban land use and stormwater management.

The Projected Impact of a Neighborhood-scaled Green Infrastructure Retrofit.

Climate change and its related factors are increasing the frequency of hurricanes, coastal storms, and urban flooding. Recovery from disasters can be slow, with jurisdictions failing to build back better, wasting time and money without improving resilience to the next disaster. To help attenuate floods and mitigate their impacts, Low Impact Development (LID) and the incorporation of green infrastructure (GI) is gaining in popularity. LID installs more natural methods of absorbing, redirecting, retaining, and filtering water, through GI installations such as rain gardens, detention ponds, and the reduction of impervious surfaces. LID is, however, primarily implemented and evaluated only on a local scale; few studies have assessed the broader impacts of GI on a larger scale. In fact, most performance calculators that evaluate the effects of GI are only useful at the site scale. Further, most advocates of GI propose its use in new developments, without much attention to retrofitting existing, suburban development. This article seeks to determine what the potential effects of retrofitting an existing, suburban neighborhood with GI for flood protection at a larger scale could be, using Sugar Land, Texas, USA as a case site. First, low-impact facilities are proposed and schematically designed at a site scale for a typical single-family lot. The volume of rainfall that can be retained on site, due to each incorporated feature, is then derived using the Green Values National Storm Water Management Calculator. Using this data, the total volume of rainfall that could be retained if all residential sites in Sugar Land incorporate similar facilities is then projected. The result show that Sugar Land has the capacity to capture 56 billion liters of stormwater water annually if all residential properties use LID. Additional benefits of the use of GI include reduced heat (37%), improved aesthetics and property values (20%), increased recreational opportunities (18%), improved water quality (12%), improved air quality (5%), increased green collar jobs (4%), reduced damage from harmful gas emissions (3%), and increased energy savings (1%), thereby surpassing conventional storm water management techniques [1].