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Editorial

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4 pages, 179 KiB

Open AccessEditorial

Green Infrastructures for Urban Water System: Balance between Cities and Nature

by Robert Sitzenfrei, Manfred Kleidorfer, Peter M. Bach and Taneha Kuzniecow Bacchin

Water 2020, 12(5), 1456; https://doi.org/10.3390/w12051456 - 20 May 2020

Cited by 5 | Viewed by 3586

Abstract

Urban water systems face severe challenges such as urbanisation, population growth and climate change. Traditional technical solutions, i.e., pipe-based, grey infrastructure, have a single purpose and are proven to be unsustainable compared to multi-purpose nature-based solutions. Green Infrastructure encompasses on-site stormwater management practices, [...] Read more.

Urban water systems face severe challenges such as urbanisation, population growth and climate change. Traditional technical solutions, i.e., pipe-based, grey infrastructure, have a single purpose and are proven to be unsustainable compared to multi-purpose nature-based solutions. Green Infrastructure encompasses on-site stormwater management practices, which, in contrast to the centralised grey infrastructure, are often decentralised. Technologies such as green roofs, walls, trees, infiltration trenches, wetlands, rainwater harvesting and permeable pavements exhibit multi-functionality. They are capable of reducing stormwater runoff, retaining stormwater in the landscape, preserving the natural water balance, enhancing local climate resilience and also delivering ecological, social and community services. Creating multi-functional, multiple-benefit systems, however, also warrants multidisciplinary approaches involving landscape architects, urban planners, engineers and more to successfully create a balance between cities and nature. This Special Issue aims to bridge this multidisciplinary research gap by collecting recent challenges and opportunities from on-site systems up to the watershed scale. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

Research

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19 pages, 1806 KiB

Open AccessArticle

Performance Evaluation of Stormwater Management Systems and Its Impact on Development Costing

by Farjana Akhter, Guna A. Hewa, Faisal Ahammed, Baden Myers and John R. Argue

Water 2020, 12(2), 375; https://doi.org/10.3390/w12020375 - 30 Jan 2020

Cited by 8 | Viewed by 5646

Abstract

The contribution of this paper is a comparison of the installation cost of a conventional drainage system consisting of a network of pits and pipes, with that of a hybrid drainage system comprising a network of pits and pipes, supported by allotment scale [...] Read more.

The contribution of this paper is a comparison of the installation cost of a conventional drainage system consisting of a network of pits and pipes, with that of a hybrid drainage system comprising a network of pits and pipes, supported by allotment scale infiltration measures in a modern greenfield residential development. The case study site is located in Pipers Crest, near Strathalbyn, South Australia. This as-built site consists of 56 allotments, 42 pits (hence 42 sub-catchments), one detention basin and over 1000 m of drainage pipes. In this study, conventional and hybrid (combination of conventional and Water Sensitive Urban Design, WSUD systems) drainage systems were designed to convey minor storm events of 10% annual exceedance probability (AEP), and checked for major storm events of 5% AEP, using the DRAINS model and/or source control principles. The installation costs of the conventional and hybrid drainage systems were estimated and compared based upon cost estimates derived from Australian literature. The results of the study indicate that satisfactory drainage was possible using the conventional or hybrid system when the two systems were designed to have outflow not exceeding the pre-developed flow. The hybrid drainage system requires smaller pipe sizes compared to the conventional system. Also, the size of the detention basin and maximum outflow rate of the hybrid system were smaller than those for the conventionally drained site. The installation cost of the hybrid drainage system was 18% less than that of the conventional drainage system when the objective was to accommodate 10% and 5% AEP storms. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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22 pages, 2175 KiB

Open AccessArticle

Sustainable Rainwater Management Concept in a Housing Estate with a Financial Feasibility Assessment and Motivational Rainwater Fee System Efficiency Analysis

by Izabela Godyń, Agnieszka Grela, Dominika Stajno and Patrycja Tokarska

Water 2020, 12(1), 151; https://doi.org/10.3390/w12010151 - 03 Jan 2020

Cited by 25 | Viewed by 4073

Abstract

Unresourceful usage of rainwater continues to be a serious problem as this type of natural resource is still treated as wastewater that most often ends up directly in the sewer system. The aim of the article is to present a concept of sustainable [...] Read more.

Unresourceful usage of rainwater continues to be a serious problem as this type of natural resource is still treated as wastewater that most often ends up directly in the sewer system. The aim of the article is to present a concept of sustainable rainwater management within a completed housing estate in Cracow (Poland). Sustainable solutions are proposed, such as rain gardens, soakaways, permeable surfaces, and infiltration boxes, limiting the surface runoff, feasible for implementation in an existing development. Their efficacy was shown by estimating the runoff reduction and two financial assessments: (1) the required investment costs converted to costs per 1 m² of residential area and as per 1 household, and (2) the assessment of financial profitability by the rate of return and the payback period, which are the basic tool for making decisions by potential investors: developers and residents. On the cost side, investment costs are included, and on the benefit side, savings resulting from the reduction of national and municipal rainwater fees. The analysis also aims to examine the incentive nature of these fees. National rainwater drainage fees, which have been introduced to encourage rainwater retention, have low non-incentive rates and the potential benefits of reducing them maybe around 1% of investment capital, which gives a payback period of almost 100 years. Higher rates of municipal fees are more motivating for investors; the proposed concept of rainwater management can potentially bring savings of around 9% (rate of return), and investment can be recovered within 12 years. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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25 pages, 4958 KiB

Open AccessArticle

Urban Spatial Configuration and Functional Runoff Connectivity: Influence of Drainage Grid Density and Landscape Metrics

by Vincent Smets, Boud Verbeiren, Martin Hermy and Ben Somers

Water 2019, 11(12), 2661; https://doi.org/10.3390/w11122661 - 17 Dec 2019

Cited by 4 | Viewed by 3167

Abstract

Due to changing precipitation patterns induced by climate change, urban planners are confronted with new challenges to effectively mitigate rainfall runoff. An important knowledge gap that needs to be addressed before tackling these challenges is how and to which extent street/drainage grid density [...] Read more.

Due to changing precipitation patterns induced by climate change, urban planners are confronted with new challenges to effectively mitigate rainfall runoff. An important knowledge gap that needs to be addressed before tackling these challenges is how and to which extent street/drainage grid density and spatial land use configuration influence the amount of runoff. Therefore, a virtual experiment was conducted to assess the influence of grid density and spatial land use configuration on the functional runoff connectivity (F_c), which is a measure of the easiness by which water flows through the landscape. Through the use of a design of experiments approach in combination with the SCS—Curve Number runoff model, a wide variety of neutral landscape models with a fixed percentage of pervious- and impervious cover were generated that maximized the variance of F_c. Correlations between landscape metrics and neutral landscape models were calculated. Our results indicated that, out of the 17 landscape metrics tested, the average impervious cluster area, the number of impervious clusters, the standard deviation of the cluster size, two proximity indexes and the effective impervious area were strongly correlated with F_c throughout all grid scenarios. The relationship between F_c on the one hand and the average impervious cluster area and the effective impervious area on the other hand, was modelled. The average impervious cluster area models showed a relationship with F_c that closely approximated a logarithmic function (R²: 0.49–0.73), while the effective impervious area models were found to have a linear relationship with F_c (R²: 0.63–0.99). A dense grid was shown to cause a strong increase in F_c, demonstrating the effectiveness of an urban grid in channeling and removing runoff. Our results further indicate that fine-grained landscapes with a lot of small impervious clusters are preferred over course-grained landscapes when the goal is to reduce F_c. In highly urbanized landscapes, where the percentage of impervious area is high, small changes in landscape pattern could significantly reduce F_c. By using a downward hydrological modeling approach this research aims to bring more clarity to the underlying variables influencing F_c, rather than trying to generate realistic prediction values. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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18 pages, 825 KiB

Open AccessArticle

Co-Design of Engineered Hyporheic Zones to Improve In-Stream Stormwater Treatment and Facilitate Regulatory Approval

by Skuyler P. Herzog, William A. Eisenstein, Brittnee N. Halpin, Andrea C. Portmann, Nicole J. M. Fitzgerald, Adam S. Ward, Christopher P. Higgins and John E. McCray

Water 2019, 11(12), 2543; https://doi.org/10.3390/w11122543 - 01 Dec 2019

Cited by 9 | Viewed by 3449

Abstract

Green infrastructure is an increasingly popular approach to mitigate widespread degradation of urban waters from stormwater pollution. However, many stormwater best management practices (BMPs) have inconsistent water quality performance and are limited to on-site, land-based deployments. To address basin-wide pollutant loads still reaching [...] Read more.

Green infrastructure is an increasingly popular approach to mitigate widespread degradation of urban waters from stormwater pollution. However, many stormwater best management practices (BMPs) have inconsistent water quality performance and are limited to on-site, land-based deployments. To address basin-wide pollutant loads still reaching urban streams, hyporheic zone engineering has been proposed as an in-stream treatment strategy. Recognizing that regulator and practitioner perspectives are essential for innovation in the water sector, we interviewed U.S. water management professionals about the perceived risks, opportunities, and knowledge gaps related to in-stream stormwater treatment. We used engineered hyporheic zones as a case study to understand interviewee perspectives on an emerging class of in-stream treatment technologies. Interviews revealed that many considerations for in-stream stormwater treatment are common to land-based BMPs, but in-stream BMPs have additional unique design and siting requirements. Here, we synthesize practitioner goals, their recommendations on in-stream BMP design, and open research questions related to in-stream BMPs. Many interviewees suggested pairing engineered hyporheic zones with other BMPs in a treatment train to improve in-stream treatment, while simultaneously reducing risk and cost. We discuss how treatment trains and other strategies might also help overcome regulatory hurdles for innovative stormwater treatment. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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17 pages, 7802 KiB

Open AccessArticle

Geographic Object Based Image Analysis of WorldView-3 Imagery for Urban Hydrologic Modelling at the Catchment Scale

by Mark Randall, Rasmus Fensholt, Yongyong Zhang and Marina Bergen Jensen

Water 2019, 11(6), 1133; https://doi.org/10.3390/w11061133 - 30 May 2019

Cited by 10 | Viewed by 3472

Abstract

China’s Sponge City initiative will involve widespread installation of new stormwater infrastructure including green roofs, permeable pavements and rain gardens in at least 30 cities. Hydrologic modelling can support the planning of Sponge Cities at the catchment scale, however, highly detailed spatial data [...] Read more.

China’s Sponge City initiative will involve widespread installation of new stormwater infrastructure including green roofs, permeable pavements and rain gardens in at least 30 cities. Hydrologic modelling can support the planning of Sponge Cities at the catchment scale, however, highly detailed spatial data for model input can be challenging to compile from the various authorities, or, if available, may not be sufficiently detailed or updated. Remote sensing methods show great promise for mitigating this challenge due to their ability to efficiently classify satellite images into categories relevant to a specific application. In this study Geographic Object Based Image Analysis (GEOBIA) was applied to WorldView-3 satellite imagery (2017) to create a detailed land cover map of an urban catchment area in Beijing. While land cover classification results based on a Bayesian machine learning classifier alone provided an overall land cover classification accuracy of 63%, the subsequent inclusion of a series of refining rules in combination with supplementary data (including elevation and parcel delineations), yielded the significantly improved overall accuracy of 76%. Results of the land cover classification highlight the limitations of automated classification based on satellite imagery alone and the value of supplementary data and additional rules to refine classification results. Catchment scale hydrologic modelling based on the generated land cover results indicated that 61 to 82% of rainfall volume could be captured for a range of 24 h design storms under varying degrees of Sponge City implementation. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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11 pages, 888 KiB

Open AccessArticle

Stormwater Retention and Reuse at the Residential Plot Level—Green Roof Experiment and Water Balance Computations for Long-Term Use in Cyprus

by Katerina Charalambous, Adriana Bruggeman, Marinos Eliades, Corrado Camera and Loukia Vassiliou

Water 2019, 11(5), 1055; https://doi.org/10.3390/w11051055 - 21 May 2019

Cited by 23 | Viewed by 4062

Abstract

Green roofs can provide various benefits to urban areas, including stormwater retention. However, semi-arid regions are a challenging environment for green roofs as long dry weather periods are met with short but intense rainfall events. This requires green roofs to retain maximum volumes [...] Read more.

Green roofs can provide various benefits to urban areas, including stormwater retention. However, semi-arid regions are a challenging environment for green roofs as long dry weather periods are met with short but intense rainfall events. This requires green roofs to retain maximum volumes of stormwater, while being tolerant to minimal irrigation supplies. The objectives of this study are (i) to quantify the stormwater retention of two substrate mixtures with two plant species under natural rainfall; (ii) to assess the performance of two plant species under two levels of deficit irrigation; and (iii) to compute stormwater runoff reduction and reuse by green roofs and rooftop water harvesting systems for three standard residential plot types in urban Nicosia, Cyprus. A rooftop experiment was carried out between February 2016 and April 2017 and results were used to compute long-term performance. Average stormwater retention of the 16 test beds was 77% of the 371-mm rainfall. A survival rate of 88% was recorded for Euphorbia veneris and 20% for Frankenia laevis, for a 30% evapotranspiration irrigation treatment. A combination of a green roof, rainwater harvesting system and 20-m³ tank for irrigation and indoor greywater use reduced stormwater runoff by 47–53%, for the 30-year water balance computations. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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Review

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16 pages, 2670 KiB

Open AccessReview

Wetland Roofs as an Attractive Option for Decentralized Water Management and Air Conditioning Enhancement in Growing Cities—A Review

by Andreas Zehnsdorf, Keani C. U. Willebrand, Ralf Trabitzsch, Sarah Knechtel, Michael Blumberg and Roland A. Müller

Water 2019, 11(9), 1845; https://doi.org/10.3390/w11091845 - 05 Sep 2019

Cited by 11 | Viewed by 6352

Abstract

While constructed wetlands have become established for the decentralized treatment of wastewater and rainwater, wetland roofs have only been built in isolated cases up to now. The historical development of wetland roofs is described here on the basis of a survey of literature [...] Read more.

While constructed wetlands have become established for the decentralized treatment of wastewater and rainwater, wetland roofs have only been built in isolated cases up to now. The historical development of wetland roofs is described here on the basis of a survey of literature and patents, and the increasing interest in this ecotechnology around the world is presented. In particular, this article describes the potential for using wetland roofs and examines experience with applications in decentralized water management in urban environments and for climate regulation in buildings. Wetland roofs are suitable as a green-blue technology for the future—particularly in cities with an acute shortage of unoccupied ground-level sites—for the decentralized treatment of wastewater streams of various origins. Positive “side effects” such as nearly complete stormwater retention and the improvement of climates in buildings and their surroundings, coupled with an increase in biodiversity, make wetland roofs an ideal multi-functional technology for urban areas. Full article

(This article belongs to the Special Issue Green Infrastructures for Urban Water System: Balance between Cities and Nature)

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