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Surface water flooding is currently viewed as the most serious water-related issue in many of the China's large cities due to rapid urbanization, land-use change and the process of rapid socio-economic development. In 2014, the People's Republic of China established the concept of the ‘Sponge City’ which will be used to tackle urban surface-water flooding and related urban water management issues, such as purification of urban runoff, attenuation of peak run-off and water conservation. The concept is being developed to make use of ‘blue’ and ‘green’ spaces in the urban environment for stormwater management and control. It is envisaged that related practices will enhance natural ecosystems and provide more aesthetically pleasing space for the people that live and work in urban environments, in addition enabling nature-based solutions to improve urban habitats for birds and other organisms. Until recently, grey infrastructure and hard engineering-based management approaches have been adopted in the rapidly developing Chinese urban environment as urban flood and drainage issues are predominantly managed by municipal water engineers. The Sponge City concept and related guidelines and practices will provide multiple opportunities to integrate ideas from eco-hydrology, climate change impact assessment and planning, and consideration of long-term social and environmental well-being, within the urban land-use planning process. This paper aims to explicate the Sponge city concept and its development, and consider the implications of the transformation of urban land-use planning and urban-water management practice in China. To achieve the dual goals of sustainable water-use and better flood control (as targeted by the Sponge City concept), more effective development and implementation of land-use guidance and assessment tools (with explicit integration of urban flood-risk assessment, land-drainage guidance, climate projection methods, and assessment of long-term sustainability) are recommended. © 2018 Elsevier Ltd

Link: https://doi.org/10.1016/j.landusepol.2018.03.005

Actions: Coastal Resilience, Sustainable use of Matter & Energy

Goals: Risk Management and Resilience, Sustainable Urbanisation in cities

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Algal blooms have become a pressing issue in inland freshwater systems on local and global scales. A plausible approach to reducing algae without the use of chemical/biological agents is through the use of UV-C radiation from lamps potentially powered by in situ solar panels to eliminate algae. Yet, the quantitative scientific base has not been established. Our objective is to conduct a controlled experiment to quantify the effectiveness of UV-C radiation on the reduction of Chlorella vulgaris, a common algal species in the Great Lakes region. A full factorial design of three intensities of UV-C radiation (0, 15, and 30�W) and three sources of C. vulgaris was constructed to test the corresponding hypotheses. Empirical models were constructed to predict the reductions. UV-C radiation effectively reduced the algal concentration with clear differences by radiation level and source of algal water. Algal concentration decreased exponentially over time, with distinct decreasing trends among the radiation intensities and the samples. With 15�W UV-C radiation, algal concentration of three samples were reduced to 75.3%, 51.5%, and 70.0% of the initial level within an hour, respectively. We also found a clear density-dependent reduction rate by UV radiation. Using this information, more efficient treatment systems could be constructed and implemented for cleaning algae-contaminated water. � 2017 Elsevier Inc.

Link: https://doi.org/10.1016/j.envres.2017.03.007

Actions: Enhancing Ecosystems' Insurance Value

Goals: Restoring Degraded Ecosystems Using NbS

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Based on a site experiment on a typical steppe of Inner Mongolia, the short term effects on aboveground biomass, soil water content, soil organic carbon, and soil total nitrogen of four cultivated pastures (CPs) with different compositions of herbaceous species were examined and compared to those of adjacent, natural grassland (NG) enclosed simultaneously. All CPs produced significantly higher aboveground biomass than did the NG after two years of establishment, and the mixed culture of Agropyron cristatum (A. cristatum) and Medicago sativa (M. sativa) produced the highest (312.39% higher than the NG). Without irrigation, soil water content in the 10-20 cm soil layer was also found to be significantly higher in the CPs than in the NG, especially for the mixed cultures of A. cristatum and M. sativa, A. cristatum, M. sativa and Lolium perenne (L. perenne), by 184.25% and 125.97%, respectively. The improvements in soil organic carbon and soil total nitrogen in CPs were less obvious and mixed, with different species compositions showing significant increases at different depths. The experimental results suggested that, with carefully selected species compositions and proper farming measures, CPs could have a positive effect on some of the pathways that generate ecosystem services, at least in the short term. We also analyzed the underlying institutional and socioeconomic causes of China's underdevelopment of CPs, and proposed a two-step development strategy. The first is to promote rain-fed CPs on small-hold farms, which require relatively low inputs in fertilizers and labor. The second is to promote large-scale operations, which will require significantly more inputs in land, irrigation, fertilizers, and machinery. © 2016 by the authors.

Link: https://doi.org/10.3390/su8040392

Actions: Sustainable use of Matter & Energy

Goals: Restoring Degraded Ecosystems Using NbS

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Introduction: Among the most dangerous pollutants is PM2.5, which can directly pass through human lungs and move into the blood system. The use of nature-based solutions, such as increased vegetation cover in an urban landscape, is one of the possible solutions for reducing PM2.5 concentration. Our study objective was to understand the importance of green spaces in pollution reduction. Methods: Daily PM2.5 concentrations were manually collected at nine monitoring stations in Nanjing over a 534-day period from the air quality report of the China National Environmental Monitoring Center (CNEMC) to quantify the spatiotemporal change of PM2.5 concentration and its empirical relationship with vegetation and landscape structure in Nanjing. Results: The daily average, minimum, and maximum PM2.5 concentrations from the nine stations were 74.0, 14.2, and 332.0 μg m−3, respectively. Out of the 534 days, the days recorded as “excellent” and “good” conditions were found mostly in the spring (30.7 %), autumn (25.6 %), and summer (24.5 %), with only 19.2 % of the days in the winter. High PM2.5 concentrations exceeding the safe standards of the CNEMC were recorded predominately during the winter (39.3–100.0 %). Our hypothesis that green vegetation had the potential to reduce PM2.5 concentration was accepted at specific seasons and scales. The PM2.5 concentration appeared very highly correlated (R2 > 0.85) with green cover in spring at 1–2 km scales, highly correlated (R2 > 0.6) in autumn and winter at 4 km scale, and moderately correlated in summer (R2 > 0.4) at 2-, 5-, and 6-km scales. However, a non-significant correlation between green cover and PM2.5 concentration was found when its level was >75 μg m−3. Across the Nanjing urban landscape, the east and southwest parts had high pollution levels. Conclusions: Although the empirical models seemed significant for spring only, one should not devalue the importance of green vegetation in other seasons because the regulations are often complicated by vegetation, meteorological conditions, and human activities. © 2016, Chen et al.

Link: https://doi.org/10.1186/s13717-016-0052-6

Actions: Carbon Sequestration, Urban Regeneration, Well-being in Urban Areas

Goals: Sustainable Urbanisation in cities

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If a ‘Renaturing of Cities’ strategy is to maximise the ecosystem service provision of urban green infrastructure (UGI), then detailed consideration of a habitat services, biodiversity-led approach and multifunctionality are necessary rather than relying on the assumed benefits of UGI per se. The paper presents preliminary data from three case studies, two in England and one in Germany, that explore how multifunctionality can be achieved, the stakeholders required, the usefulness of an experimental approach for demonstrating transformation, and how this can be fed back into policy. We argue that incorporating locally contextualised biodiversity-led UGI design into the planning and policy spheres contributes to the functioning and resilience of the city and provides the adaptability to respond to locally contextualised challenges, such as overheating, flooding, air pollution, health and wellbeing as well as biodiversity loss. Framing our research to encompass both the science of biodiversity-led UGI and co-developing methods for incorporating a strategic approach to implementation of biodiversity-led UGI by planners and developers addresses a gap in current knowledge and begins to address barriers to UGI implementation. By combining scientific with policy learning and defined urban environmental targets with community needs, our research to date has begun to demonstrate how nature-based solutions to building resilience and adaptive governance can be strategically incorporated within cities through UGI. © 2016 Elsevier Ltd

Link: https://doi.org/10.1016/j.envsci.2016.01.013

Actions: Urban Regeneration, Well-being in Urban Areas

Goals: Sustainable Urbanisation in cities

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Margins of water reservoirs associated with dams can have high-frequency tides, promoting soil erosion and nutrient leaching. We propose the use of biocrusts for restoration and ecological engineering purposes, due to their poikilohydric character, to stabilize reservoir margins. We promoted biocrust growth under controlled conditions, testing two types of substrate: native sand and organic substrate. After 2 months, biocrusts grew on organic substrate covering almost all the area, but not on native sand. This fast and easy nature-based solution for soil stabilization can be used as an environmental engineering tool in highly degraded sites. © 2018 Society for Ecological Restoration

Link: https://doi.org/10.1111/rec.12688

Actions: Enhancing Ecosystems' Insurance Value, Watershed Management & Ecosystem Restoration

Goals: Restoring Degraded Ecosystems Using NbS

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Despite their evidently different assumptions and operationalization strategies, the concepts of Circular Economy, Green Economy and Bioeconomy are joined by the common ideal to reconcile economic, environmental and social goals. The three concepts are currently mainstreamed in academia and policy making as key sustainability avenues, but a comparative analysis of such concepts is missing. The aim of this article is thus to comprehensively analyse the diversity within and between such concepts. The results are drawn from a bibliometric review of almost two thousand scientific articles published within the last three decades, coupled with a conceptual analysis. We find that, for what concerns environmental sustainability, Green Economy acts as an ‘umbrella' concept, including elements from Circular Economy and Bioeconomy concepts (e.g. eco-efficiency; renewables), as well as additional ideas, e.g. nature-based solutions. In particular, Circular Economy and Bioeconomy are resource-focused, whereas in principle Green Economy acknowledges the underpinning role of all ecological processes. Regarding the social dimension, Green Economy is more inclusive of some aspects at local level (e.g. eco-tourism, education), while there is an emerging discussion in Bioeconomy literature around local processes in terms of biosecurity and rural policies. When considering weak/strong sustainability visions, all concepts remain limited in questioning economic growth. By comparing the different sustainability strategies promoted by these concepts we do not advocate for their substitutability, but for their clarification and reciprocal integration. The findings are discussed in light of the concepts' synergies and limits, with the purpose to inform research and policy implementation. © 2017 The Authors

Link: https://doi.org/10.1016/j.jclepro.2017.09.053

Actions: Sustainable use of Matter & Energy

Goals: Climate Change Adaptation and Mitigation

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The growing evidence base for the benefits for people and wildlife of nature-based solutions to managing urban green infrastructure lacks research investigating land manager perspectives on their implementation. To address this gap, we explored UK local authority manager perceptions of the challenges and opportunities of introducing perennial urban meadows to prioritise biodiversity and aesthetics. This was co-produced as an experiment in urban greenspaces with Luton Parks Service and Bedford Borough Council 2013–15. We conducted semi-structured interviews with the eight stakeholder managers involved to identify key factors impacting on the perceived feasibility of future urban meadow establishment in other areas. All managers identified three dominant factors (aesthetics and public reaction, locational context, and human resources and economic sustainability). Additional factors (local politics, communication, biodiversity and existing habitat and physical factors) varied in importance according to personal values and managerial role. Support for future meadow introduction and a desire to overcome the economic challenge of the disposal of meadow arisings were related to manager biocentricity. Managers were aware of changing public values leading to increasing acceptance of a messier urban aesthetic. They perceived perennial meadows as a realistic alternative to amenity mown grass that in specific contexts could increase local biodiversity and enhance aesthetics if implemented in consultation with the public and local councillors. Our findings have relevance for the wider implementation of such nature-based solutions to urban GI management: Changes in management practice such as the introduction of perennial meadows have significant political, strategic, economic and practical implications and cannot be viewed purely as a technical challenge. © 2017 The Authors

Link: https://doi.org/10.1016/j.ufug.2017.05.009

Actions: Carbon Sequestration, Urban Regeneration, Well-being in Urban Areas

Goals: Climate Change Adaptation and Mitigation, Sustainable Urbanisation in cities

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A high percentage of urban areas are covered by impermeable surfaces which reduce infiltration and landscape retention of stormwater. Moreover, the pollution flushed from these areas, particularly after intensive rainfall, is often drained directly to rivers and reservoirs which, in many cases, also serve a recreational function in cities. Stormwater runoff contributes to degradation of aquatic ecosystems and their intensified eutrophication which, in growing seasons, results in toxic cyanobacterial blooms. The hybrid system (combined of engineering and biological measures) tested in this research was constructed in 2013 in Łódź city (POLNAD) to retain and purify stormwater runoff from a street that runed directly to a cascade of recreational reservoirs. The hybrid system consists of an underground separators system that is combined with a sequential sedimentation-biofiltration system (SSBS). In the first two years of the system's operation, it effectively reduced pollution transported to the urban river system by reducing 86.0% of total suspended solids, 71.5% of total nitrogen (TN), 66.7% of total phosphorous (TP), and from 40.7% to 78.3% of PO4 3− and NO2 −, respectively. In addition, the system was able to reduce the hydraulic stress induced by extreme discharges and mitigated discharges for precipitation amounts less than 9 mm. The hybrid system is an example of a nature-based solution measure reducing the negative effects of nutrients transfer, eutrophication and flooding in urbanized areas, as part of the blue-green infrastructure. © 2017 Elsevier B.V.

Link: https://doi.org/10.1016/j.ecoleng.2017.09.019

Actions: Sustainable use of Matter & Energy, Urban Regeneration, Well-being in Urban Areas

Goals: Sustainable Urbanisation in cities

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Nature-based solutions promoting green and blue urban areas have significant potential to decrease the vulnerability and enhance the resilience of cities in light of climatic change. They can thereby help to mitigate climate change-induced impacts and serve as proactive adaptation options for municipalities. We explore the various contexts in which nature-based solutions are relevant for climate mitigation and adaptation in urban areas, identify indicators for assessing the effectiveness of nature-based solutions and related knowledge gaps. In addition, we explore existing barriers and potential opportunities for increasing the scale and effectiveness of nature-based solution implementation. The results were derived from an inter- and transdisciplinary workshop with experts from research, municipalities, policy, and society. As an outcome of the workshop discussions and building on existing evidence, we highlight three main needs for future science and policy agendas when dealing with nature-based solutions: (i) produce stronger evidence on nature-based solutions for climate change adaptation and mitigation and raise awareness by increasing implementation; (ii) adapt for governance challenges in implementing nature-based solutions by using reflexive approaches, which implies bringing together new networks of society, nature-based solution ambassadors, and practitioners; (iii) consider socio-environmental justice and social cohesion when implementing nature-based solutions by using integrated governance approaches that take into account an integrative and transdisciplinary participation of diverse actors. Taking these needs into account, nature-based solutions can serve as climate mitigation and adaptation tools that produce additional cobenefits for societal well-being, thereby serving as strong investment options for sustainable urban planning. © 2016 by the author(s).

Link: https://doi.org/10.5751/ES-08373-210239

Actions: Carbon Sequestration, Coastal Resilience, Urban Regeneration, Well-being in Urban Areas

Goals: Climate Change Adaptation and Mitigation, Sustainable Urbanisation in cities

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