On the Effectiveness of Domestic Rainwater Harvesting Systems to Support Urban Flood Resilience

The effectiveness of domestic rainwater harvesting (DRWH) systems to support urban flood resilience is analysed at the sub-catchment scale, according to a specific DRWH conversion scenario, under 4 degrees of urbanization, 3 drainage network configurations, 4 precipitation regimes and 3 return periods of the rainfall event. At this aim, a suitable modelling framework is implemented: the semi-distributed hydrologic-hydraulic model is undertaken using EPASWMM 5.1.007 where specific tools are developed to simulate DRWH systems at high spatial resolution. The effectiveness of the DRWH systems simulated for the 144 different cases, is analysed at the event scale by using the Volume and Peak Reduction indexes to measure the hydrologic performance. The dimensionless variable, namely the event storage fraction, is defined in order to easily describe the DRWH effectiveness. The event storage fraction is defined as the ratio between the event runoff volume resulting from the impervious surface of the urban catchment in the reference scenario and the storage capacity of the DRWH systems. Modelling results confirm that DRWH catchment-scale applications allow to support specific stormwater control requirements based on peak-flow or volume regulations strategies. Findings of the elaboration reveal for a typical residential catchment in the Italy-France cross-border coastal area, that DRWH effectiveness in supporting the urban flood management becomes significant (i.e. Volume and Peak Reduction indexes greater than 0.2) starting from a storage event fraction of 0.4 that means realizing storage tanks able to contain at least the 40% of runoff volume generated by the targeted event at the sub-catchment scale

Evaluating the Effectiveness of Bioretention Cells for Urban Stormwater Management: A Systematic Review

Bioretention cells (BRCs) are a promising low-impact development (LID) practice that are commonly used in urban settings to improve the water quality and mitigate the hydrological effects of stormwater runoff. BRCs have been the subject of extensive research in order to better comprehend their function and improve their effectiveness. However, BRC performance differs greatly among regions in terms of hydrologic performance and quality enhancement. Due to this variance in BRC effectiveness, the current study conducted a comprehensive systematic review to answer the question, "Are BRCs an effective LID method for urban catchment stormwater management?". This review study analyzed the effectiveness of BRCs in mitigating hydrologic impacts and enhancing the quality of stormwater runoff in urban catchments. A review of 114 field, laboratory, and modeling studies on BRCs found that the promising BRCs may be one of the most successful approaches to restore urban hydrology cycle and improve stormwater water quality. With further development of BRCs, their performance in terms of quantity and quality will become more reliable, helping to develop long-term solutions to stormwater urban drainage issues. At the end of this review, the knowledge gaps and future prospects for BRC research are presented. In addition to providing a foundational grasp of BRC, this review study outlines the key design recommendations for BRC implementation in order to address the issues raised by certain BRC design errors

The laboratory calibration of a soil moisture capacitance probe in sandy soils

Determining and mitigating landslide risk is a technical-scientific objective, particularly for the protection and proper territorial management and planning. The slope stability depends on the pore pressure distribution, which is influenced by the saturation front propagation through the unsaturated zone, whose monitoring is useful to understand any possible instabilities. Such monitoring may be undertaken by sensors based on the measurement of the relative dielectric permittivity. Reliable relationships between the measurement and the soil moisture are necessary. The main objective of this study is to assess a laboratory calibration protocol for a specific capacitance sensor (Drill & Drop, Sentek Sensor Technologies). Two monogranular sands have been selected for the calibration purpose. The laboratory tests were performed under three relative density values (DR equal to 40%, 60% and 80%) for seven volumetric water content values (\u3b8v ranging from 0.00% to 36.26%). Based on the experimental measurements, the soil-specific calibration curves were determined at an assigned relative density value; in particular, a simple power law is adopted to describe the probe\u2019s reading as a function of the volumetric water content. The results point out that the relative density values slightly affect the tests, thus, the soil-specific calibration curves are derived based on a simple regression analysis fitting the whole set of the laboratory tests validated for each sand. The calculated coefficient of determination (R2 = 0.96\uf70.99) and root mean square error (RMSE = 1.4%\uf72.8%) values confirm the goodness of fit. In order to propose more general fitting curves, suitable for both the investigated sands, multiple linear regressions are performed by considering \u3b8v and the mean grain size, D50 as independent variables; again, the R2 and RMSE values equal to 0.97 and 2.41%, respectively, confirm the suitability of the calibration curve. Finally, the laboratory calibration curves are compared with the manufacturer-supplied curves, thus, enhancing the need for the soil-specific calibration

Assessing the socio-economic benefits from green and blue space rehabilitation: a case study for the Confluence area in Lyon

This paper aims to demonstrate the added socio-economic value of green/blue spaces inurban areas. The Sustainable Urban Landscape Development (SULD) hedonic pricingsimulation model is applied to the case-study of Confluence in Lyon, France. Scenariosimulations are performed for the establishment of urban parks, along with the requalificationof riverfronts and development of road infrastructure. Results show that the first twointerventions (parks and parks plus requalification) attract high-income households and,hence, lead to increases in real estate values up to +28%. The latter intervention (parks plusnew road infrastructure) also attracts low-income households, which leads to a smallerincrease in real estate values. SULD aids in improving urban planning strategies, in terms ofdrafting plans, public discussion and monitoring

Balancing social and economic impacts of nature-based solutions for storm water management = Équilibrer les impacts sociaux et économiques des solutions écologiques pour la gestion des eaux pluviales

FR: Les espaces verts et bleus sont mis sous pression alors que les zones urbaines se densifient, sedéveloppent et évoluent. Pourtant, il est avéré que ces espaces fournissent des servicesécosystémiques essentiels - dont la gestion des eaux de ruissellement (inondations), la constructiond'abris pour la faune et la flore (biodiversité) et l'amélioration du cadre de vie (esthétique et récréatif).Ces solutions basées sur l'ingénierie écologique pour des risques d'inondation sont une priorité pourla recherche et dans l'agenda politique européen. La mise en place de ces solutions peut toutefoisconduire à la gentrification des quartiers, où une demande accrue immobilière des ménages àrevenus plus élevés conduit à une augmentation des valeurs immobilières et au déplacement desménages à faible revenu. Cette étude vise à évaluer et à comparer les impacts sociaux etéconomiques des solutions écologiques dans un projet de requalification urbaine à La Confluence(Lyon, France), en utilisant un modèle de simulation hédonique (SULD). Les résultats montrent troisgrandes tendances en ce qui concerne la mise en place de ces solutions dans les paysages urbains:i) l'augmentation de la densité de population, ii) l'augmentation des prix de l'immobilier, et iii) lechangement dans les modes de distribution démographiques. Ces effets de gentrification peuvent êtreatténués par, entre autres, la requalification simultanée des grandes infrastructures routières quipeuvent réduire les déplacements des ménages à faible revenu.Urban green and blue spaces are put under pressure as urban areas grow, develop and evolve. It isincreasingly recognized, however, that green/blue spaces provide critical ecosystem services -including regulating (flood control), habitat (biodiversity) and cultural (aesthetic and recreational)services. These so-called nature-based solutions for flood risk adaptation are a key priority on theEuropean research and policy agenda, given their contribution to welfare and human well-being. Theestablishment of nature-based solutions may, however, lead to gentrification where increased realestate demand from higher-income households leads to increased real estate values and thedisplacement of lower-income households. This paper aims to assess and compare the social andeconomic impacts of nature-based solutions in an urban-requalification project in the Confluence(Lyon, France), using the Sustainable Urbanizing Landscape Development (SULD) hedonic pricingsimulation model. Results show three major tendencies regarding the establishment of nature-basedsolutions in urban landscapes: i) population densities increase, ii) real estate values rise, and iii)demographic distribution patterns change. These gentrification effects may be dampened by, amongstothers, the simultaneous requalification of major road infrastructure that leads to reduceddisplacement of lower-income households

Sustainable Urbanizing Landscape Development (SULD) decision support tool: report on other Aqua Cases. Aqua-Add project

"This report has been developed in the context of the international co-operation projectAqua-Add (Deploying the added value of water in local and regional development), aiming atthe sharing of knowledge and experience between project partners as to better deploy thepotential of 'water' (economically, socially and environmentally) in urbanised landscapes andto improve the implementation of water measures in local and regional spatialdevelopment. Aqua-Add not only collects, analyses, disseminates and promotes the specificfunctions, services and values of green/blue spaces, but also develops and applies a DecisionSupport Tool (DST) that: i) demonstrates the (potential) social, environmental and economicimpacts of different water management scenarios, and ii) facilitates the planning processand better informed decision making across stakeholders.The objective of this report is twofold. First, the importance of stakeholder meetings in thedevelopment and application of the Sustainable Urbanizing Landscape Development (SULD;Roebeling et al., 2007, 2014) decision support tool is assessed. In particular, the extent towhich these meetings facilitated the identification, assessment and communication ofdifferent views and interests and, in turn, encouraged the effective engagement ofstakeholders in the participative design of (peri-) urban development plans. Second, theapplication of SULD to the other Aqua Cases (Bremerhaven DE; Copenhagen DK; DebrecenHU; Imperia IT; Lyon FR; Sofia BU) is presented and discussed, to assess the impact oflocation-specific green/blue space and infrastructure projects on the location of residentialdevelopment, housing quantity, residential development density, population density,population composition, household living space and real estate values. (,,,)

Green Roofs to Improve Water Management

Green roofs are increasingly used as sustainable urban drainage system due to their positive impact on the storm water management. The mitigation consists in reducing the total outflow volume, while delaying the initial time of runoff and distributing the outflow over a longer time period. The retention, detention and infiltration processes promote the occurrence of adsorption and dissolution mechanisms throughout the green roof components generally limiting the total pollutant mass delivered on an event basis. An overview of the green roofs hydrologic performance metrics as well as experimental data to provide a quantitatively assessment is presented. Similarly the impact of green roof in altering storm water quality is examined based on the observed pollutant loads reported in the literature. Finally, the needs for future research and suggestions for green roofs integration in urban water mitigation strategies are discussed