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Green roofs (GRs) are a widely recognized green infrastructure (GI) strategy that helps reduce runoff volume and runoff pollution caused by the significant increase in impervious urban areas. However, the leaching of several nutrients from GR substrates is a growing concern. Biochar, a carbon-rich material, possesses advantageous properties that can help address such environmental challenges associated with GRs. Therefore, this paper aimed to undertake a field study to investigate the impacts of various biochar application methods, particle sizes, and amendment rates on the quality of runoff from GRs. Observational data of runoff quality were collected over a two-month period from five newly established 1 m × 1 m biochar-amended GR test beds and a control test bed without biochar, with all test beds subjected to artificially simulated rainfall. The results indicated that the addition of biochar did not result in a significant improvement in runoff pH, whereas the electrical conductivity (EC) was higher in runoff from GRs with biochar-amended substrates. When comparing the total nitrogen (TN) concentration in runoff from the non-biochar GR (ranging from 3.7 to 31 mg/L), all biochar test beds exhibited higher TN release (4.8 to 58 mg/L), except for the bed where medium biochar particles were applied at the bottom of the substrate (ranging from 2.2 to 21 mg/L). Additionally, all biochar-amended GRs exhibited higher TP concentrations in runoff (0.81 to 2.41 mg/L) when compared to the control GR (0.35 to 0.67 mg/L). Among the different biochar setups, GR with fine biochar particles applied to the surface of the substrate had the poorest performance in improving runoff water quality. Despite these mixed results, biochar holds significant potential to improve runoff quality by significantly increasing water retention, thereby reducing pollutant loads. [ABSTRACT FROM AUTHOR]

A one-year study was conducted to evaluate the impact of air pollution and roof coating on runoff quality. An existing 440 sq meter bitumen roof of a single-story building was coated with an extensive green roof layer on one half. Rainfall and runoff samples from both roofs were collected during 11 rainfall events after the separation of the first flush. The study monitored several key parameters, including pH, electrical conductivity (EC), turbidity, chemical oxygen demand (COD), ammonium nitrogen, nitrate nitrogen, and phosphates. The study revealed that both types of roofs altered the rainfall quality, but the changes caused by the green roof were more substantial. Although the retention of runoff from green roofs has a widely acknowledged positive impact on collecting systems, our study shows that green roofs also result in a 7.5- fold increase in COD concentrations, a 5.4-fold increase in the sum of ammonium and nitrate nitrogen, and a 2.3-fold increase in phosphates compared to bitumen roofs. A clear link between the quality of rainwater/runoff and air pollution was not established. The study's findings will aid in the development and management of local rainwater harvesting systems and enhance global understanding of the primary quality parameters of various roof types, particularly in regions with air pollution. [ABSTRACT FROM AUTHOR]

The results of research aimed at assessing the quality of runoff from ‘green’ roofs as a source of pollutants, particularly heavy metals, are presented. It is justified that the majority of scientific studies dedicated to studying the quality of stormwater from “green” roofs indicate that these systems can improve the quality of runoff by reducing the concentration of pollutants and enhancing water balance regulation in urban areas. The results of research confirming the change in pH values in stormwater from “green” roofs compared to rainwater are provided. The influence of vegetation types and substrate composition of “green” roofs on the physicochemical composition of rainwater is analyzed. It is shown that “green” roofs with a dual substrate, where a mixture of activated carbon with perlite and vermiculite can be used as an adsorption layer, are effective in absorbing organic substances, heavy metals, and all forms of nitrogen for varying intensities of rainfall. The impact of the age (duration of use) of the “green” roof on the quality of runoff is analyzed. It is mentioned that the lowest quality of runoff is observed in the early stages of “green” roof operation, but water quality generally improves over time as the substrate and vegetation stabilize within the ecosystem conditions. It is shown that the quality index of runoff from a “green-blue” roof is higher compared to a ‘green’ or traditional roof. The results of scientific research confirming the effectiveness of “green” roofs in terms of changing the concentration of organic substances (COD, BOD), heavy metals, nitrogen, phosphorus, pH, and turbidity are presented. The main factors influencing the quality of surface water runoff from “green” roofs are justified and proposed. A diagram illustrating the circulation of pollutants in the “green” roof system and the potential of different factors acting as sources or absorbers of pollutants is provided.

Green roofs (GRs) are a widely recognized green infrastructure (GI) strategy that helps reduce runoff volume and runoff pollution caused by the significant increase in impervious urban areas. However, the leaching of several nutrients from GR substrates is a growing concern. Biochar, a carbon-rich material, possesses advantageous properties that can help address such environmental challenges associated with GRs. Therefore, this paper aimed to undertake a field study to investigate the impacts of various biochar application methods, particle sizes, and amendment rates on the quality of runoff from GRs. Observational data of runoff quality were collected over a two-month period from five newly established 1 m × 1 m biochar-amended GR test beds and a control test bed without biochar, with all test beds subjected to artificially simulated rainfall. The results indicated that the addition of biochar did not result in a significant improvement in runoff pH, whereas the electrical conductivity (EC) was higher in runoff from GRs with biochar-amended substrates. When comparing the total nitrogen (TN) concentration in runoff from the non-biochar GR (ranging from 3.7 to 31 mg/L), all biochar test beds exhibited higher TN release (4.8 to 58 mg/L), except for the bed where medium biochar particles were applied at the bottom of the substrate (ranging from 2.2 to 21 mg/L). Additionally, all biochar-amended GRs exhibited higher TP concentrations in runoff (0.81 to 2.41 mg/L) when compared to the control GR (0.35 to 0.67 mg/L). Among the different biochar setups, GR with fine biochar particles applied to the surface of the substrate had the poorest performance in improving runoff water quality. Despite these mixed results, biochar holds significant potential to improve runoff quality by significantly increasing water retention, thereby reducing pollutant loads.

Green roofs are becoming popular in urban areas due to their potential benefits, including energy efficiency, urban heat island mitigation, and stormwater management. However, their water consumption can negatively impact water resources. Therefore, carefully managing the water consumption of green roofs is crucial to ensure they do not exacerbate existing water scarcity issues. This review explores the influencing factors and innovative solutions that increase the sustainability of water management on green roofs. A systematic quantitative review was conducted on published studies on green roofs. The review highlighted that while small-scale experimental studies are almost saturated, large-scale monitoring studies are still lacking. Modelling and assessing green roof settings based on climatic conditions and water availability and consumption are essential for successful water management. Using integrated technologies and sensing systems can increase water management efficiency and sustainability. Rainwater may be sufficient as a water source for green roofs in wet climates, while irrigation is still needed in other climates. Phytoremediation and biosorption can potentially increase runoff water quality. Improving hydrological performance by increasing rainwater retention and reducing water consumption capacity can reduce demand for other water resources and effectively manage small storms, mitigating pressure on city infrastructure and increasing water quality. Seeking non-potable sources, such as greywater, or harvesting enough rainwater to be used for irrigation during dry weather periods is highly advantageous for improving the sustainability of green roofs.

Green roofs are becoming popular in urban areas due to their potential benefits, including energy efficiency, urban heat island mitigation, and stormwater management. However, their water consumption can negatively impact water resources. Therefore, carefully managing the water consumption of green roofs is crucial to ensure they do not exacerbate existing water scarcity issues. This review explores the influencing factors and innovative solutions that increase the sustainability of water management on green roofs. A systematic quantitative review was conducted on published studies on green roofs. The review highlighted that while small-scale experimental studies are almost saturated, large-scale monitoring studies are still lacking. Modelling and assessing green roof settings based on climatic conditions and water availability and consumption are essential for successful water management. Using integrated technologies and sensing systems can increase water management efficiency and sustainability. Rainwater may be sufficient as a water source for green roofs in wet climates, while irrigation is still needed in other climates. Phytoremediation and biosorption can potentially increase runoff water quality. Improving hydrological performance by increasing rainwater retention and reducing water consumption capacity can reduce demand for other water resources and effectively manage small storms, mitigating pressure on city infrastructure and increasing water quality. Seeking non-potable sources, such as greywater, or harvesting enough rainwater to be used for irrigation during dry weather periods is highly advantageous for improving the sustainability of green roofs. [ABSTRACT FROM AUTHOR]

Urban stormwater runoff is considered as one of the major contributors to nonpoint source that contributes to the pollution of all water resources in the surrounding environment. Pollutant concentrations of urban stormwater runoff are directly or indirectly linked with land use types in a catchment that is quite different in different places, and hence, site-specific studies are necessary, unless otherwise the modelling of runoff quality using modelling tools may not be rationally reflected the actual field scenarios. This paper portrays the influence of land use types on stormwater runoff physicochemical quality in Chattogram city, where land use's demarcation is often complicated due to the different natural and human-induced anthropogenic factors. The stormwater runoff samples were collected from the residential, commercial, institutional, and industrial land use types, in the city of Chattogram, Bangladesh, during the period from July to September 2020. The standard laboratory protocol for elemental concentrations and principal component analysis was performed in addition to basic statistics to identify the influence of urban surface characteristics on the quality of stormwater runoff. In general, pollutant concentrations were identified by analysing key physical and chemical quality parameters including colour, temperature, turbidity, total suspended solids (TSS), total dissolved solids (TDS), electrical conductivity (EC), salinity, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) and exhibited 2 to 3 times higher concentrations than reported elsewhere. Furthermore, the present study reported the greater concentrations of few pollutants, such as TSS, BOD5, and EC, derived from the residential land uses compared to other land use types that are surprising; however, it confirmed the distinct complexity of unplanned land use patterns that should not be overlooked rather discussed. The strong correlation between land use types and stormwater runoff quality indicates the site-specific influences of runoff quality. The outcomes of this study would be particularly helpful in calibrating water quality models considering different land use types. Additionally, datasets and information obtained from this research will assist engineers and practitioners in developing decision-making tools for effective stormwater management. [ABSTRACT FROM AUTHOR]

Extensive nutrient leaching has been a major concern in the establishing stage of green roofs. Although an addition of biochar to the green roof substrates has been increasingly recommended, the extent to which this addition can affect the runoff quality is still largely unknown. Using biochars made from maize straws (MSB) and rice husks (RHB), this study investigated the effects of biochar addition rates (0%, 10%, 15%, and 20% biochar, v/v) on the runoff quality of new green roofs over 6 months. Our results show that the addition of biochar significantly affected the runoff quality. With an increasing biochar addition rate (10∼20%), the mean total nitrogen (TN) concentration in the runoff decreased from 103.68 mg L − 1 (CK) to 26.21∼52.77 mg L − 1 (RHB) and 10.12∼3.97 mg L − 1 (MSB), the mean dissolved organic carbon (DOC) concentration decreased from 94.47 mg L − 1 (CK) to 101.76∼59.41 mg L − 1 (RHB) and 52.45∼26.73 mg L − 1 (MSB), and the mean pH increased from 7.15 (CK) to 7.42∼7.50 (RHB) and 7.49∼7.71 (MSB). However, the mean total phosphorus (TP) concentration increased from 0.27 mg L − 1 (CK) to 0.22∼0.57 mg L − 1 (RHB) and 0.58∼1.07 mg L − 1 (MSB). Generally, the N and DOC concentrations were lower in the treatment with added MSB than RHB, but the P concentrations and pH were higher. The N concentration was significantly negatively correlated with the single rainfall and cumulative rainfall in the CK- and RHB-added treatments but not in the MSB-added treatments, suggesting that the addition of MSB affected the process of N leaching from the substrate. Overall, we recommend adding 10% maize straw biochar to the green roof substrate to reduce the initial nutrient leaching from the new green roof and improve the runoff water quality. [ABSTRACT FROM AUTHOR]

Green roofs (GR) are known as one of the most effective water-sensitive urban design (WSUD) strategies to deal with numerous environmental and social issues that urbanized cities face today. The overall quality of research on GRs has significantly improved and an increasing trend is observed in the amount of research over the last decade. Among several approaches, the application of modeling tools is observed to be an effective method to simulate and evaluate the performance of GRs. Given that studies on GRs at a catchment scale are limited, this paper aims to provide a simple but effective framework for estimating the catchment-scale impacts of GR on runoff quantity and quality. MUSICX, an Australian-developed software that possesses the advantages of a conceptual model, is chosen as the modeling tool in this study. While MUSICX has built-in meteorological templates for Australian regions, this tool also supports several climate input file formats for application by modelers in other parts of the world. This paper presents two different modeling approaches using the Land Use node and Bioretention node in MUSICX. The steps used for model calibration are also provided in this paper. The modeling results present the annual reductions in runoff volume, total suspended solid (TSS), total phosphate (TP), and total nitrogen (TN) load. The largest reductions of roughly 30% per year were observed in runoff volume and TN load. The annual runoff reduction rate reported in this study is close to that of other published results. Similar research outcomes quantifying the benefits of GRs play a major role in facilitating the widespread implementation of GRs due to the awareness of both positive and negative impacts of GRs. Future studies are recommended to concentrate on modeling the impacts of implementing GRs at a large scale (i.e., scales exceeding the single-building scale) to fill the research gaps and enhance the modeling accuracy. [ABSTRACT FROM AUTHOR]

• Designed an upper-drainage position for green roof models. • Conducted 48 experiments by changing drainage method, slope, rainfall and vegetation. • Evaluated runoff and water quality for runoff control performance. • Demonstrated the upper-drainage position has better runoff control performance. The capacity of extensive green roofs (EGRs) in runoff reduction and pollutants control significantly decreased with increasing rainfall intensity. This is attributed to most of EGRs are the lower-drainage method and use a thinner substrate layer because of the structural load-bearing limits of buildings. Existing solutions depend on increasing the rainwater storage by thickening the substrate layer of EGRs, or replacing the substrate materials. We propose to enhance the water retention capacity of EGRs by adjusting vertical drainage positions and moving the lower-drainage at the bottom to upper-drainage over the substrate layer. To test the runoff control performance of EGRs with the upper-drainage method, we designed three EGR models with two different (upper- and lower-) drainage methods based on the common EGR's structure in practice and carried out total 48 experiments under different rainfall intensities with an artificial rainfall simulator. The experimental design also included adjusting structural factors of the EGR to further explore the influences of roof slope, status of vegetation growth (height and canopy cover ratio), and model size. The average runoff retention rate for the upper-drainage EGR was 61.82 %, which was much higher than the 23.94 % for the lower-drainage EGR. The concentrations of TN and TP in runoff with the upper-drainage were 2.83 and 0.18 mg/L, which were much lower than the 8.47 and 2.10 mg/L for the lower-drainage EGR. EGRs with upper-drainage overall performed better in runoff control than EGRs with lower-drainage. Vegetation height and model size did not significantly affect the rainwater control performance for different drainage methods, while the change of slope affected the rainwater interception of the EGRs with upper-drainage method. [ABSTRACT FROM AUTHOR]

Given the rapid pace of urbanization and resulting pressures on water supplies in many regions, landscape water conservation has become increasingly important for many communities. To achieve this goal, programs incentivizing partial or complete removal of turfgrass lawns have been developed by many municipalities. While prior studies have been published examining effects of urban land change on stormwater runoff, few have addressed how the transition from traditional home lawns to alternative water-efficient landscapes alters runoff water quality. The objective of this 13-month study was to compare differences in stormwater runoff quality attributes among five commonly used urban residential mesocosms including established St. Augustinegrass lawn and four alternative residential mesocosms including xeriscaping, mulch, artificial turf, and sand-capped lawn. Runoff quality parameters including pH, electrical conductivity, nitrate–N, ammonium-N, dissolved organic N, total dissolved N, orthophosphate-P, total suspended solids, and dissolved organic carbon were monitored. Results demonstrated that export of nutrients via runoff, specifically N and P, were influenced by mesocosm type. In particular, artificial turf showed elevated runoff nitrate–N relative to other mesocosms, possibly due to minimal plant absorption of inorganic N coming onto plots as dry and wet deposition. However, an additional layer of compacted decomposed granite used for xeriscapes and artificial turf seems to have protected legacy soil P from leaving the system as runoff. Collectively, the findings of this study demonstrate that there is no one specific landscape that is best suited for mitigating runoff quality, but rather, alternative mesocosms should be selected based on local climate and environmental concerns. [ABSTRACT FROM AUTHOR]

This study evaluated the potential effects of long-term land use and climate change on the quality of surface runoff and the health risks associated with it. The land use change projection 2030 was derived from the main changes in land use from 2009 to 2019, and rainfall data was obtained from the Long Ashton Research Station Weather Generator (LARS-WG) model. The Long-Term Hydrological Impact Assessment (L-THIA) model was then utilized to calculate the rate of runoff heavy metal (HM) pollutant loading from the urban catchment. It was found that areas with heavy development posed a significantly greater public health risk associated with runoff, with higher risks observed in high-development and traffic areas compared to industrial, residential, and commercial areas. Additionally, exposure to Lead (Pb), Mercury (Hg), and Arsenic (As) was found to contribute significantly to overall non-carcinogenic health risks for possible consumers of runoff. Carcinogenic risk values of As, Cadmium (Cd), and Pb were also observed to increase, particularly in high-development and traffic areas, by 2030. This investigation offers important insight into the health risks posed by metals present in surface runoff in urban catchment areas under different land use and climate change scenarios. [Display omitted] • Long-Term Hydrologic Impact Assessment was used to calculate runoff pollutant. • Long Ashton Research Station and Land-use Change Model predicted rainfall and land. • Human health impacts of runoff from different land uses were assessed. • Lead had the highest ingestion exposure, followed by Mercury, Arsenic and Cadmium. • Arsenic emerged as primary contributor to carcinogenic health risks from runoff. [ABSTRACT FROM AUTHOR]

Green roofs (GR) are known as one of the most effective water-sensitive urban design (WSUD) strategies to deal with numerous environmental and social issues that urbanized cities face today. The overall quality of research on GRs has significantly improved and an increasing trend is observed in the amount of research over the last decade. Among several approaches, the application of modeling tools is observed to be an effective method to simulate and evaluate the performance of GRs. Given that studies on GRs at a catchment scale are limited, this paper aims to provide a simple but effective framework for estimating the catchment-scale impacts of GR on runoff quantity and quality. MUSICX, an Australian-developed software that possesses the advantages of a conceptual model, is chosen as the modeling tool in this study. While MUSICX has built-in meteorological templates for Australian regions, this tool also supports several climate input file formats for application by modelers in other parts of the world. This paper presents two different modeling approaches using the Land Use node and Bioretention node in MUSICX. The steps used for model calibration are also provided in this paper. The modeling results present the annual reductions in runoff volume, total suspended solid (TSS), total phosphate (TP), and total nitrogen (TN) load. The largest reductions of roughly 30% per year were observed in runoff volume and TN load. The annual runoff reduction rate reported in this study is close to that of other published results. Similar research outcomes quantifying the benefits of GRs play a major role in facilitating the widespread implementation of GRs due to the awareness of both positive and negative impacts of GRs. Future studies are recommended to concentrate on modeling the impacts of implementing GRs at a large scale (i.e., scales exceeding the single-building scale) to fill the research gaps and enhance the modeling accuracy.

Green roofs have gained global acceptance as a technology that is beneficial for both the environment and the urban population. It is generally believed that green roofs also improve the quality of runoffs. The article presents the results of a 6-years study of water quality in runoffs from extensive green roofs of different constructions with respect to the quality of rainwater and runoff from a reference roof. The research results show that analyzed green roofs are capable of neutralizing runoffs and should not be also regarded as sources of ammonium nitrogen pollution in runoffs. Apart from the positive effects, these green roofs can also have a negative influence on the quality of runoffs. The high total concentrations of nitrite nitrogen, nitrate nitrogen, phosphates, and the content of organic substances that do not undergo biodegradation observed in the runoffs. Based on the results of this research it can be inferred that the influence of green roofs on the runoff quality will improve during the operation period, but not for all quality indicators. There is a need to focus more on the quality of green roof runoff. It should be controllable through better design, management, and maintenance of green roofs. [ABSTRACT FROM AUTHOR]

Green roofs of young age (≤ 5 years old) have boomed in China since the Sponge City Construction initiative was implemented. To use green roofs for better urban stormwater management, it is necessary to investigate the runoff quality of field-scale young green roofs as well as to examine common plant-media combination in green roof projects of China. The influence of two Sedum-vegetated extensive green roofs of different designs at the early stage of operation on runoff water quality was investigated by a field-scale study in Chengdu, southwest China. The water quality parameters of pH, suspended solids (SS), chemical oxygen demand (COD), total phosphorus (TP), and total nitrogen (TN) of rainwater (that is, input water for roofs), runoff from the two green roofs, and runoff from a conventional concrete control roof were compared. The results indicate that both green roofs mainly act as pollutant sources with greater concentrations of SS, COD, and TP when compared with rainwater quality. When compared with runoff quality from the control roof, greater TP concentrations in runoff from one green roof with commercially available substrate were observed. Attention should be paid to TP leaching in runoff for retrofitted green roofs with imported commercial substrates in that region. Adoption of pre-cultivated S. lineare mats of low fertility and localized soils may reduce nutrient leaching in green roof runoff. A nitrogen-rich substrate is not recommended for a plant community of a single species. Investigation of the effect of green roofs on water quality involving various pollutants in the long run is recommended. [ABSTRACT FROM AUTHOR]

Green roofs (GRs) and vertical greenery systems (VGSs) can contribute certain pollutants to stormwater runoff, affecting the quality of the receiving waters. The objective of this review paper is to discuss the potential impact of these systems on the quality of urban runoff. In the green building systems section, a series of materials used in greenery systems and their specific application are presented and environmentally relevant substances that could be leached out from these materials are identified as potential pollutants. After the identification of environmentally relevant pollutants that have already been measured in urban runoff and originate from these systems, an assessment of their pathways, fate, and impact in the aquatic environment is performed. Since GRs and VGSs are already considered to be solutions for stormwater quantity and quality management in urban areas, recommendations for mitigating their environmental impact through runoff are needed. It can be concluded that special focus should be placed on measures that target the pollution source, such as optimizing GR and VGS construction practices and materials used, as well as establishing appropriate decentralized stormwater treatment measures. Both of these approaches will help to reduce or even entirely avoid the emission of relevant pollutants into the aquatic environment.

The wellbeing, socio-economic viability and the associated health of the inhabitant species of any ecosystem are largely dependent on the quality of its water resources. In this regard, we developed a protocol to measure the potential impact of various environmental and anthropogenic factors on runoff quality at 22 water sampling sites across the Bumbu Watershed in Papua New Guinea. For this purpose, we utilized Digital Elevation Models and several GIS techniques for delineation of stream drainage patterns, classification of the watershed based on Land Use/Land Cover, spatial interpolation of rainfall patterns and computation of the corresponding factor runoff. Our study concludes that a variety of potential challenges to surface water quality are possible such as natural geologic and geochemical inputs, runoff accumulation of precipitation and organic matter pollutants. The developed protocol can also accommodate socio-economic factors such as community and household health, sanitation and hygiene practices, pollution and waste disposal. This research lays the foundation for further development of an all-inclusive correlational analysis between the relative importance values of the factors influencing runoff and spatially distributed water quality measurements in the Bumbu basin.

This review is a synthesis of the current knowledge regarding the effects of green roof substrate components and their retentive capacity for nutrients, particularly phosphorus (P). Substrates may behave as either sources or sinks of P depending on the components they are formulated from, and to date, the total P-adsorbing capacity of a substrate has not been quantified as the sum of the contributions of its components. Few direct links have been established among substrate components and their physicochemical characteristics that would affect P-retention. A survey of recent literature presented herein highlights the trends within individual component selection (clays and clay-like material, organics, conventional soil and sands, lightweight inorganics, and industrial wastes and synthetics) for those most common during substrate formulation internationally. Component selection will vary with respect to ease of sourcing component materials, cost of components, nutrient-retention capacity, and environmental sustainability. However, the number of distinct components considered for inclusion in green roof substrates continues to expand, as the desires of growers, material suppliers, researchers and industry stakeholders are incorporated into decision-making. Furthermore, current attempts to characterize the most often used substrate components are also presented whereby runoff quality is correlated to entire substrate performance. With the use of well-described characterization (constant capacitance model) and modeling techniques (the soil assemblage model), it is proposed that substrates optimized for P adsorption may be developed through careful selection of components with prior knowledge of their chemical properties, that may increase retention of P in plant-available forms, thereby reducing green roof fertilizer requirements and P losses in roof runoff. [ABSTRACT FROM AUTHOR]

The concentration levels of selected chemical compositions in samples of rainwater (precipitation - open atmosphere) and runoff waters from different rooftop buildings and parking lots of Al al-Bayt University premises in Jordan have been presented and analyzed. The runoff from rooftop buildings and parking lots was compared to rainwater collected for the concentrations of the following major cations and anions: Na+1, K+1, Mg+2, Ca+2, HCO3-1, Cl-1, NO3-1, SO4-2, as well as heavy metals: Al+3, Pb+2, Mn+2 and Cd+3. Furthermore, pH and total dissolved solids (TDSs) were measured. Sampling procedures were basically depending on 11 rainstorms taken after rainfall events over a period of 6 months, between December 2010 and May 2011. Average concentrations of Al+3, Cl-1, HCO3-1, Mg+2, Na+1, Mn+2, SO4-2 and TDSs were found to be less than or equal to those given in the Jordanian Water Standard (JWS) for drinking water, while for Ca+2, the average concentration, exceeds that given in the Jordanian Water Standard (JWS) (=75 mg/l) for all roofing materials. K+1 concentration was found to be larger than that given in the JWS (=20 mg/l) for most of the roofing materials. Additionally, the average concentration for NO3-1 was found to be larger than that given in the JWS (=50 mg/l) for seal coat. Two categories of water type were found: mixed Ca+2 - Mg+2 - Cl- -type and Ca+2 - HCO3- type. The average concentration order of all roofing materials can be arranged as follows in terms of quality of harvested water: metal insulation < mixed concrete insulation < mixed asphalt insulation = concrete insulation < water insulation = seal coat insulation < roll asphalt insulation < thermal insulation. [ABSTRACT FROM AUTHOR]

Growth substrate plays an important role in determining the quality of runoff from green roofs. However, no systematic research has been conducted to design a substrate to improve runoff quality. Hence, the present study aimed at designing and developing a green roof substrate using low-cost and environmentally-benign materials. The inorganic fraction of the substrate includes purosil, vermiculite, sand and light-weight clay aggregates (LECA); whereas the organic fraction includes coco-peat andSargassum wightii. Through factorial design, 13 different substrate mixes were prepared and the optimum mix (20% purosil, 30% vermiculite, 10% sand, 20% LECA, 10% coco-peat and 10%S. wightii) was found to have high water holding capacity (67.6%), air filled porosity (21%), hydraulic conductivity (5524 mm/h) and low bulk density (495 kg/m3). The substrate also provided maximum support for the growth ofPortulaca oleracea. Experiments with metal-contaminated influent from the down-flow of a packed reactor revealed that the green roof substrate possesses a high sorption capacity towards various metal ions. [ABSTRACT FROM AUTHOR]

Urbanization leads to higher phosphorus (P) concentration in urban catchments. Among different stormwater retention measures, green roofs are the least efficient in phosphorus retention. Moreover, much research has shown that green roofs act as sources of phosphorus, and they can emit P in significant loads. In this study low P emission green roof substrate was developed based on the proposed step by step procedure for the selection of materials including laboratory tests, column experiments, and the monitoring of the open air green roof model. Developed substrate is the mixture of crushed red brick (35% of volume), crushed limestone (20% of volume), and sand (45% of volume), and is characterized by a bulk density of 1.52 g/cm³, water permeability of 9 mm/min, water capacity of 24.6% of volume, and granulometric composition that meets the Landscaping and Landscape Development Research Society (FLL) guidelines. Limestone was added to limit the potential P leaching from crushed red brick and vegetated mate consisted of Sedum album, Sedum acre, Sedum kamtschaticum, Sedum spurium, Sedum reflexum, Sedum sexangulare, Dianthus deltoides, Dianthus carthusianorum, and Thymus vulgaris. The open air model experiment was run for 319 days, from March 2015 to February 2016. The total water runoff from the green roof model amounted to 43.3% of runoff from the reference roof. The only one runoff event polluted with phosphorus was connected with the outflow of melted snow from an unfreezing green roof model. [ABSTRACT FROM AUTHOR]

Characterising stormwater runoff quality provides useful insights into the dynamics of pollutant generation and wash off rates. These can be used to prioritise stormwater management strategies. This study examined the effects of a low intensity rainfall climate on zinc contributions from different impermeable urban surface types. First flush (FF) and steady state samples were collected from seven different surfaces for characterisation, and the data were also used to calibrate an eventbased pollutant load model to predict individual 'hotspot' surfaces across the catchment. Unpainted galvanised roofs generated very high concentrations of zinc, primarily in the more biologically available dissolved form. An older, unpainted galvanised roof had FF concentrations averaging 32,338 µg/L, while the new unpainted roof averaged 4,782 µg/L. Roads and carparks also had elevated zinc, but FF concentrations averaged only 822-1,584 µg/L. Modelling and mapping expected zinc loads from individual impermeable surfaces across the catchment identified specific commercial roof surfaces to be targeted for zinc management. The results validate a policy strategy to replace old galvanised roof materials and avoid unpainted galvanised roofing in future urban development for better urban water quality outcomes. In the interim, readily-implemented treatment options are required to help mitigate chronic zinc impacts on receiving waterways. [ABSTRACT FROM AUTHOR]

Green roofs (GRs) are a feasible solution for mitigating increased runoff volumes in urban areas. Though many studies have focused their analysis on the quantity and quality of GR runoff, with respect to the relevance of specific site conditions in GR performance, the information gathered for the tropical Andes is not sufficient. This study assessed the hydrological performance and runoff water quality of 12 green roof modular systems located at the Universidad de los Andes campus (Bogotá, Colombia). Based on 223 rainfall events spanning a 3-year period, average rainfall retention was 85% (coefficient of variation = 29%). t-tests, the Welch Test, multiple linear regressions, and correlation analysis were performed in order to assess the potential effect of air temperature, substrate type, vegetation cover, relative humidity, antecedent dry weather period (ADWP), rainfall duration, and rainfall maximum intensity. In some cases, GR design variables (i.e., substrate type and vegetation cover) were found to be significant for describing rainfall retention efficiencies and, depending on the GR type, some hydrological variables were also correlated with rainfall retention. Rainfall and GR runoff from 12 rainfall events were also monitored for total Kjeldahl nitrogen (TKN), nitrates, nitrites, ammonia, total phosphorus (TP), phosphates, pH, total dissolved solids (TDS), total suspended solids (TSS), color, turbidity, biological oxygen demand (BOD), chemical oxygen demand (COD), total coliforms, metals (i.e., zinc, copper, nickel, lead, selenium, aluminum, barium, boron, calcium, strontium, iron, lithium, magnesium, manganese, potassium, sodium), and polyaromatic hydrocarbons (PAHs). The results obtained confirmed that GR systems have the ability to neutralize pH, but are a source of the rest of the aforementioned parameters, excluding PAHs (with concentrations below detection limits), ammonia, TSS, selenium and lithium, where differences with control cases (rainfall and plastic panel runoff) were not statistically significant. Substrate type, event size, and rainfall regime are relevant variables for explaining runoff water quality.

Pollutant first flush (FF) is a critical phenomenon in urban regions driven by multiple factors. Therefore, having a robust mathematical FF definition and modeling tool along with thorough knowledge of its main influencing variables, is essential. Machine-learning techniques have been widely exploited in the water-quality field; however , their use to predict FF occurrence and pollutant load is limited. This study developed a generic machine-learning framework based on the two most commonly adopted FF definitions (30/80 and M(V) curve) and implemented for three of the most detected pollutants in urban areas (TSS, TN, and TP). This framework is able to accurately predict if a rainfall event generates FF and, in case it does, the correspondent pollutant load ("very good" model performance). It can also quantify and rank the most influencing factors using a non-model-biased method based on game theory (Shapley Additive exPlanations (SHAP)), showing that the rainfall variables are the most significant predictors of sediment and nutrient FF occurrence in urban regions. The findings proved that the machine-learning framework developed in this study can be a valuable modeling tool for improving the accuracy and reliability of pollutant load prediction during FF events in urban areas. Furthermore, they represent one of the first steps towards a robust mathematical FF definition, which is still a topic under debate. • The machine-learning framework satisfactorily predicts pollutant load. • It ranks the influencing variables by their importance in predicting pollutant load. • It is implemented for three pollutants and two first-flush definitions. • It can be applied to any geographical region. • Accurate pollutant-load predictions will aid first-flush treatment system design. [ABSTRACT FROM AUTHOR]

Green roof substrates are usually designed to achieve desirable characteristics such as low bulk density, preparation cost, high water holding capacity (WHC), hydraulic conductivity (HC) and airfilled porosity (AFP). However, no importance is given to sorption capacity or leaching potential of substrate. Thus, in the present study, novel attempt was made to incorporate a brown-seaweed ( Turbinaria conoides ) in growth substrate to enhance the runoff quality from green roofs. The green roof substrate, prepared using 30% perlite, 20% vermiculite, 10% sand, 20% crushed brick, 10% cocopeat and 10% T. conoides , was found to have favourable characteristics such as low bulk density (477.7 kg/m 3 ), high WHC (49.5%), AFP (20.5%) and HC (4210 mm/h). With the aid of down-flow fixed column, sorption capacity of green roof substrate towards various metal ions (Na, K, Ca, Mg, Al, Fe, Cd, Cu, Cr, Ni, Pb and Zn) was examined and results indicated that the column was able to operate for 1440 min at a flow rate of 5 mL/min before outlet Ni concentration reached the inlet. Green roof experiments were performed using pilot-scale assemblies with Portulaca grandiflora as vegetation. Under rainfall simulations, it was observed that vegetated-green roof assemblies acted as a sink for various metal ions and produced better runoff. In addition, green roofs buffered acidic rain and delayed runoff generation. [ABSTRACT FROM AUTHOR]

The ArcSWAT2009 model with an improved sub-model (SWAT-GC) was used to assess plant growth to evaluate sediment and nutrient runoff yields from an alternating grass-covered/tilled inter-row vineyard (VP) and from disk harrowing (DH) and grass cover (GC) management techniques in an olive orchard in Castelfiorentino (Florence), Tuscany, Italy. The model was calibrated for field plots (0.11 to 0.12 ha) using runoff volume and composition measured from January 2010 to December 2010 and validated using measured data from January 2011 to August 2013. The results obtained with the SWAT-GC were compared with those obtained with the standard model (SWAT) calibrated in situ. Daily performance of the calibrated SWAT model in simulating runoff, sediment, and nutrient yields for all treatments was good or very good according to the Nash–Sutcliffe model efficiency (NSE), the mean percentage error (M%E), and the median-based root mean square error (RSR). However, based on validation results, daily performance of the SWAT model was unsatisfactory. On the contrary, the SWAT-GC model provided very good predictions of average daily runoff and soil and nutrient loss during both the calibration and validation periods. Moreover, results indicate that SWAT-GC model is capable of adequately modeling differences in nutrient yields between the different tillage practices by calibrating crop growth, runoff, and sediment yields only. In fact, calibration for N and P resulted in identical calibration parameters regardless of tillage practice on olive orchard. [ABSTRACT FROM AUTHOR]

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The present study examines whether green roofs act as a sink or source of contaminants based on various physico-chemical parameters (pH, conductivity and total dissolved solids) and metals (Na, K, Ca, Mg, Al, Fe, Cr, Cu, Ni, Zn, Cd and Pb). The performance of green roof substrate prepared using perlite, vermiculite, sand, crushed brick, and coco-peat, was compared with local garden soil based on improvement of runoff quality. Portulaca grandiflora was used as green roof vegetation. Four different green roof configurations, with vegetated and non-vegetated systems, were examined for several artificial rain events (un-spiked and metal-spiked). In general, the vegetated green roof assemblies generated better-quality runoff with less conductivity and total metal ion concentration compared to un-vegetated assemblies. Of the different green roof configurations examined, P. grandiflora planted on green roof substrate acted as sink for various metals and showed the potential to generate better runoff. [ABSTRACT FROM AUTHOR]

Many studies worldwide have investigated the potential benefits achievable by transforming brown roofs of buildings to green roofs. However, little literature examined the runoff quality/sorption ability of green roofs. As the green roof substrate is the main component to alter the quality of runoff, this investigation raises the possibility of using a mixture of low-cost inorganic materials to develop a green roof substrate. The tested materials include exfoliated vermiculite, expanded perlite, crushed brick and sand along with organic component (coco-peat). Detailed physical and chemical analyses revealed that each of these materials possesses different characteristics and hence a mix of these materials was desirable to develop an optimal green roof substrate. Using factorial design, 18 different substrate mixes were prepared and detailed examination indicated that mix-12 exhibited desirable characteristics of green roof substrate with low bulk density (431 kg/m³), high water holding capacity (39.4%), air filled porosity (19.5%), and hydraulic conductivity (4570 mm/h). The substrate mix also provided maximum support to Portulaca grandiflora (380% total biomass increment) over one month of growth. To explore the leaching characteristics and sorption capacity of developed green roof substrate, a down-flow packed column arrangement was employed. High conductivity and total dissolved solids along with light metal ions (Na, K, Ca and Mg) were observed in the leachates during initial stages of column operation; however the concentration of ions ceased during the final stages of operation (600 min). Experiments with metal-spiked deionized water revealed that green roof substrate possess high sorption capacity towards various heavy metal ions (Al, Fe, Cr, Cu, Ni, Pb, Zn and Cd). Thus the developed growth substrate possesses desirable characteristics for green roofs along with high sorption capacity. [ABSTRACT FROM AUTHOR]

Green roofs recover green spaces in urban areas and benefit the public, farmers, and wildlife by providing many environmental, ecological, and economic advantages. Green roofs reduce stormwater runoff, mitigate urban heat island effects, absorb dust and smog, sequester carbon dioxide, produce oxygen, create space for food production, and provide natural habitat for animals and plants. Here, we studied the environmental impact of green roofs in terms of runoff quality and greenhouse gas CO sequestration. We screened more than 650 scientific papers and we reviewed detailed findings from 52 publications. There are two major points: (1) Concerning pollution, the concentrations of minor pollutants, such as heavy metals, biochemical oxygen demand (BOD), total suspended solids (TSS), and turbidity, are small and thus do not pose an immediate threat to the environment. However, the concentrations of major pollutants, such as nitrogen of 0.49-9.01 mg/l and phosphorus of 0.04-25 mg/l, vary highly for different green roofs and can adversely affect runoff quality. Nutrient leaching may be controllable through proper mitigation measures including better design and system management which require further research. According to both laboratory experiments and field monitoring data, the main factors affecting runoff quality are precipitation properties, growth media composition and depth, plant species, and maintenance protocols. Research gaps exist in quantifying how these factors affect leachate pollutant load. Systematic studies are needed for improving green roof designs to reduce adverse impacts. (2) Concerning CO sequestration, studies reveal that green roofs directly sequester substantial amounts of carbon in plants and soils through photosynthesis. Green roofs reduce ambient CO concentrations in the vicinities. Green roofs also indirectly reduce CO releases from power plants and furnaces by reducing demand for heating and cooling, suggesting long-term economic and environmental benefits of green roofs. [ABSTRACT FROM AUTHOR]

Monitoring the quality and quantity of agricultural runoff offers many challenges. Various instruments are available and range in terms of complexity, initial costs, operating costs, and accuracy. This paper describes a low-cost multislot passive sampler (the crown divisor sampler) used to measure runoff from a 0.41 ha (1 ac) field. Similar samplers have been used in laboratory and plot-scale studies, but their accuracy has not been studied in the field. For this study, the crown divisor sampler was placed in series with a calibrated 0.2 m (0.8 ft) HS flume. The accuracy of the sampler was assessed by comparing the runoff volume predicted by the sampler to the known volume measured by the flume for several storm events. A series of tests were also performed in which a simulated storm event was routed through the flume and crown divisor sampler. The flume was acceptably accurate for the simulated storm event tests and for some of the storm events. In addition to the quantitative results, many practical lessons have been learned and are documented in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Green roofs have multiple environmental benefits and are widely used around the world. In keeping with this mainstream movement, the use of green roofs has been increasing in Taiwan in recent years. This paper reviews policies promoting green roof development in Taiwan, and compares the environmental and economic performance of green roofs in Taiwan to those in East Asian countries and worldwide. National and regional government policies have stimulated the development of green roofs by establishing goals for reducing carbon emissions of cities, promoting green construction, mitigating heat island effects, and increasing urban flood control. Local studies of green roof performance are few, other than thermal investigations. These studies have shown that green roofs significantly contribute to thermal reduction and moderate temperature variations around buildings. One study sampled stormwater runoff from green roof sites and found that sediment and nutrient concentration on these roofs are up to ten times higher than on conventional bare roofs; however, acid rain can be neutralized by green roofs. Hydrographs have shown that reductions in runoff from green roofs are not as great as expected because retention and detention are affected by high rainfall intensity, which is the typical precipitation pattern in Taiwanese cities. Without additional maintenance, green roofs can contribute to nonpoint source pollution in urban cities in wet and hot weather zones, because of high runoff and associated mass loading. Moreover, the environmental benefits of green roofs in Taiwan may not be as significant as those in other countries in which utility costs are higher, where decreasing energy consumption and CO2 emissions would be of greater benefit. [Copyright &y& Elsevier]

Conversion from annual cropping to perennial forages may be a beneficial management practice (BMP) to reduce runoff quantity and improve surface water quality. Runoff variables were determined in two 30 ha producer's fields over 4 years (2004-2007) using a rainfall simulator. Field 1 was cropped to barley (Hordeum vulgare L.) in 2004 and then an alfalfa (Medicago sp.) and grass mix used for hay and fall grazing was grown from 2005 to 2007. Field 2 was cropped to barley-winter triticale (WT) (Triticosecale Rimpavi Wittm.) in 2005 and alfalfa-grass for hay was grown in 2006 and 2007. Runoff variables measured were runoff depth, electrical conductivity, and concentrations and loads of total suspended solids, total N, total P, and dissolved reactive P fractions. Conversion from barley to alfalfa-grass for hay and fall grazing in Field 1 resulted in reductions for only 13% of the 10 runoff variables, 33% of runoff variables were unaffected, and 53% of variables were significantly increased. Conversion from barley-WT to alfalfa-grass used for hay in Field 2 significantly reduced 25% of the 10 variables, 40% were unaffected, and 35% were significantly increased. Converting from annual cropping to forage did not improve the majority of runoff variables. [ABSTRACT FROM AUTHOR]

Summary: Stormwater drainage systems can have a large effect on urban runoff quality, but it is unclear how ephemeral urban streams alter runoff hydrochemistry. This problem is particularly relevant in semi-arid regions, where urban storm runoff is considered a renewable water resource. Here we address the question: how do stream channels alter urban runoff hydrochemistry? We collected synoptic stormwater samples during three rainfall–runoff events from nine ephemeral streams reaches (three concrete or metal, three grass, three gravel) in Tucson, Arizona. We identified patterns of temporal and spatial (longitudinal) variability in concentrations of conservative (chloride and isotopes of water) and reactive solutes (inorganic-N, soluble reactive phosphorous, sulfate-S, dissolved organic carbon (DOC) and nitrogen, and fecal indicator bacteria). Water isotopes and chloride (Cl) concentrations indicate that solute flushing and evapoconcentration alter temporal patterns in runoff hydrochemistry, but not spatial hydrochemical responses. Solute concentrations and stream channel solute sourcing and retention during runoff were significantly more variable at the grass reaches (CV=2.3−144%) than at the concrete or metal (CV=1.6−107%) or gravel reaches (CV=1.9−60%), which functioned like flow-through systems. Stream channel soil Cl and DOC decreased following a runoff event (Cl: 12.1–7.3μgg−1 soil; DOC: 87.7–30.1μgg−1 soil), while soil fecal indicator bacteria counts increased (55–215CFUg−1 soil). Finding from this study suggest that the characteristics of the ephemeral stream channel substrate control biogeochemical reactions between runoff events, which alter stream channel soil solute stores and the hydrochemistry of subsequent runoff events. [Copyright &y& Elsevier]

In order to investigate the characterization of runoff in storm sewer from various urban catchments, three monitoring systems at different spatial scales have been installed separately. They have been held since July 2010 in urban area of Beijing (China). The monitoring data revealed that chemical oxygen demand (COD), total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), and NH3-N values significantly exceed the Class V surface water quality standard developed by Ministry of Environmental Protection of the People's Republic of China (MEP). A surface solids buildup and wash off model for small watershed was adopted to analyze and discuss the process of a runoff pollutant discharge. More than a half of pollutant parameters presented a good fit to the model. However, a slightly worse-fit to the wash off model appeared in less than half of the data. Due to the influence of sewer sediments, sewer system characteristics, catchment characteristics, and other reasons, first flush was seldom observed in storm sewer runoff from these three survey areas. Meanwhile, the correlation between TSS and any other pollutant was analyzed according to cumulative load of pollutants in runoff events. An event mean concentrations (EMCs) approach was adopted to quantify the pollution of runoff. EMCs of various pollutants in storm sewer runoff between different rainfall events were slightly higher than the typical values observed in similar areas at home and abroad, according to other studies reported in literature. Based on quantitative analysis, it can be concluded that urban nonpoint source pollution is recognized as the major causes of quality deterioration in the receiving water bodies. This is after the point source pollution has been controlled substantially in Beijing. An integrated strategy, which combines centralized and decentralized control, along with the conditions of meteorology, hydrology, urban planning, existing drainage system, etc., will be an effective and economic approach to urban runoff pollution control. [ABSTRACT FROM AUTHOR]

Abstract: Green (vegetated) roofs are emerging as practical strategies to improve the environmental quality of cities. However, the impact of green roofs on the storm water quality remains a topic of concern to city planners and environmental policy makers. This study investigated whether green roofs act as a source or a sink of various metals (Na, K, Ca, Mg, Al, Fe, Cu, Cd, Pb, Zn, Mn, Cr, Ni, Li and Co), inorganic anions (, , , , Cl−, F− and Br−) and cation (). A series of green roof assemblies were constructed. Four different real rain events and several artificial rain events were considered for the study. Results showed that concentrations of most of the chemical components in runoff were highest during the beginning of rain events and subsided in the subsequent rain events. Some of the important components present in the runoff include Na, K, Ca, Mg, Li, Fe, Al, Cu, , and . However, the concentration of these chemical components in the roof runoff strongly depends on the nature of substrates used in the green roof and the volume of rain. Based on the USEPA standards for freshwater quality, we conclude that the green roof used in this study is reasonably effective except that the runoff contains significant amounts of and . [Copyright &y& Elsevier]

The use of sustainable drainage systems (SuDS) or best management practice is becoming increasingly common. However, rather than adopting the preferred 'treatment train' implementation, many developments opt for end-of-pipe control ponds. This paper discusses the use of SuDS in series to form treatment trains and compares their potential performance and effectiveness with end-of-pipe solutions. Land-use, site and catchment characteristics have been used alongside up-todate guidance, Infoworks CS and MUSIC to determine whole-life-costs, land-take, water quality and quantity for different SuDS combinations. The results presented show that the use of a treatment train allows approaches differing from the traditional use of single SuDS, either source or 'end-of pipe', to be proposed to treat and attenuate runoff. The outcome is a more flexible solution where the footprint allocated to SuDS, costs and water quality can be managed differently to fully meet stakeholder objectives. [ABSTRACT FROM AUTHOR]

Installation of intensive and extensive green roofs is becoming popular for reducing runoff from impervious surfaces in many cities around the world. Most studies on runoff quality from green roofs have been conducted in cooler northern climates. We examined the losses and gains of nutrients, cations and selected anions in planted and unplanted growth medium and compared these to initial growth medium (IGM) typically used for green roof modules in south-central Texas. Water extracts of growth medium and leachate from three replicates of unplanted growth medium and three planted species ( Sedum kamtschaticum, Delosperma cooperi and Talinum calycinum) were examined. During the first 6 months after establishment we observed high losses of nitrate (25 to 44 mg kg), dissolved organic carbon (DOC: 155 to 190 mg kg) and nitrogen (DON: 9.0 to 11.2 mg kg) and orthophosphate-P (1 to 2 mg kg). Average leachate concentrations based on four rain events 6 months after establishment ranged from 0.3 to 6.6 mg L in planted modules and 6.3 mg L in unplanted modules for nitrate-N, 38 to 42 mg L in planted modules and 32 mg L in unplanted modules for DOC, 2.1 to 3.1 mg L in planted modules and 2.1 mg L in unplanted modules for DON and 0.27 to 0.37 mg L in planted modules and 0.40 mg L in unplanted modules for orthophosphate-P. We suggest that after the establishment of green roofs, leachate losses may contribute some runoff concentrations of nitrogen, carbon and phosphorous in urban areas. [ABSTRACT FROM AUTHOR]

Green-factor systems, rating the "ecological value" of a site and the green factors for landscape elements according to their positive effects on the ecosystem, are adaptable and applicable to many cities. The "positive effects" of landscape elements, however, vary with climatic and geographic conditions. One method of evaluating elements such as green roofs, permeable pavement, vegetated walls, rain gardens, and bioswales considers their contribution to stormwater management. In this study, runoff depth, volume, peak-flow rate, and the mass loading of contaminants, determined through analysis of a typical Calgary residential site using climatic data and simulation tools (NRCS-CN, crop coefficient, and Rational Methods), are compared with those of two green-intervention scenarios with differing landscape elements achieving a Seattle Green Factor of 0.3. Calculated results show that Scenario 1--with green roofs and vegetated walls--could reduce total annual runoff volume by 31 percent, peak-flow runoff by 17 percent, mass loading of total suspended solids by 8 percent, and nutrient content to 36 percent. Scenario 2--with green roofs, permeable pavement, rain garden and bioswales--could reduce total annual runoff volume by 96 percent, peak-flow runoff by 28 percent, mass loading by 90 percent, and nutrient content to 96 percent. [ABSTRACT FROM AUTHOR]

The use of sustainable drainage systems (SUDS) or best management practice (BMP) is becoming increasingly common. However, rather than adopting the preferred "treatment train" implementation, many developments opt for end-of-pipe control ponds. This paper discusses the use of SuDS in series to form treatment trains and compares their potential performance and effectiveness with end-of-pipe solutions. Land use, site and catchment characteristics have been used alongside up-to-date guidance, Infoworks CS and the model for urban stormwater improvement conceptualisation to determine whole-life-costs, land take, water quality and water quantity for different SuDS combinations. The results presented show that the use of a treatment train allows approaches differing from the traditional use of single SUDS, either source or "end-of-pipe", to be proposed to treat and attenuate runoff. This outcome provides a more flexible solution where the footprint allocated to SUDS, costs and water quality can be managed differently to more comprehensively meet stakeholder objectives. [ABSTRACT FROM AUTHOR]

Abstract: This review paper addresses the role of green roofs in urban drainage considering both management of water quantity and quality. Results from investigation of full scale installations as well as from laboratory models are reviewed. The following factors affecting runoff dynamics from green roofs are discussed: type of green roof and its geometrical properties (slope); soil moisture characteristics; season, weather and rainfall characteristics; age of green roof; vegetation. Design parameters as suggested by different authors are also reviewed. Factors which affect influence of a green roof on runoff water quality are discussed in general terms followed by the review of data regarding concentrations of phosphorus, nitrogen, and heavy metals in green roof runoff, its’ pH, and first flush effect. Linking among fertilization, runoff pollution and vegetation development is given a particular focus. The review indicates clearly that there is a need for more research into a green roof performance in an urban environment. The differences measured by few existing studies between the early years performance of green roofs and the later years indicate a need for long term monitoring of green roofs. [Copyright &y& Elsevier]

The use of Sustainable Drainage Systems (SuDS) or Best Management Practice (BMP) is becoming increasingly common. However, rather than adopting the preferred "treatment train" implementation, many developments opt for end of pipe control ponds. This paper discusses the use of SuDS in series to form treatment trains and compares their potential performance and effectiveness with end of pipe solutions. Land-use, site and catchment characteristics have been used alongside up-to-date guidance, Infoworks CS and MUSIC to determine whole-life-costs, land-take, water quality and water quantity for different SuDS combinations. The results presented show that the use of a treatment train allows approaches differing from the traditional use of single SuDS, either source or "end of pipe", to be proposed to treat and attenuate runoff. The outcome is a more flexible solution where the footprint allocated to SuDS, costs and water quality can be managed differently to satisfy more efficiently the holistically stakeholders' objectives. [ABSTRACT FROM AUTHOR]

This paper describes a preliminary evaluation of two types of greenwaste (fresh and aged) used as a mulch layer to control runoff from disturbed landfill areas. Fresh greenwaste refers to woody and herbaceous garden waste that has been recently collected, chopped and shredded. Aged greenwaste is greenwaste which has been stockpiled for 18 months. We used rainfall simulator tests to investigate two aspects: (1) the performance of greenwaste mulch in reducing runoff during designed storm events with a high frequency of occurrence and (2) the release of pollutants via runoff as total suspended solids (TSS) and total organic carbon (TOC) during rain. Rainfall of <5-year average recurrence interval (ARI) was generally applied, consistent with stormwater compliance requirements for many Australian landfills. TOC released from fresh greenwaste material was higher in concentration than from aged greenwaste. However, when used as a 10-cm-deep mulch layer, fresh greenwaste was able to completely prevent runoff, even when tested under rainfalls of up to 50-year ARI duration. An equivalent mulch layer of aged greenwaste was also effective in reducing runoff volume and TSS concentration compared with the bare soil during a 3.5-year ARI rainfall, but mean TOC concentration was higher. Based on these preliminary results, fresh greenwaste mulching of bare soils is an attractive option to control runoff and erosion from areas subject to intermittent landfill operations and worthy of further investigations. [ABSTRACT FROM AUTHOR]

The purpose of this preliminary study was to evaluate the quality of stormwater runoff, and determine the impact of land use on the level of runoff contamination. To accomplish this, 36 samples were collected from 6 sampling locations in the 'Al-Asema' governorate - the capital of the state of Kuwait - over six rain events. Samples were analysed for total suspended solids, total dissolved solids, volatile suspended solids, chemical oxygen demand, biochemical oxygen demand, pH, total coliform, and oil and grease. The results indicated that land use had a significant influence on the major water quality constituents. Stormwater runoff was highly polluted exceeding the accepted limit for TSS, BOD, and total coliform. [ABSTRACT FROM AUTHOR]

Abstract: Vegetated roofs are becoming a trend in urban design, among others as a tool for city greening, mitigating urban heat island effect, and lowering urban storm runoff. Additionally, pollutant removal within vegetated roofs is often expected; however, it is commonly not a design feature. This study investigated influence on runoff water quality from two full-scale vegetated roofs (an intensive from Japan and an extensive from Sweden). Results show that both extensive and intensive vegetated roofs are a sink of nitrate nitrogen and ammonium nitrogen with similar performance. The intensive vegetated roof is also a sink of total nitrogen in contrast to the extensive roof. Phosphorus release is observed from the extensive vegetated roof but not from the intensive vegetated roof; release of dissolved organic carbon and potassium is observed from both roofs. The vegetated roofs, if not retaining the metal pollutants, were generally not a significant source. The increase of average pH during rainwater passage through the intensive vegetated roof indicated rapid neutralization of the acid depositions. [Copyright &y& Elsevier]