Knowledge Repository

Aerosols affect the insolation at ground and thus the Aerosol Optical Depth (AOD, a measure of aerosol pollution) plays an important role on the variation of the Physiological Equivalent Temperature (PET) at locations with different aerosol climatology. The aerosol effects upon PET were studied for the first time at four East Asian cities by coupling a radiative transfer model and a human thermal comfort model which were previously well evaluated. Evident with the MODIS and AERONET AOD observations, the aerosol pollution at Beijing and Seoul was higher than at Chiayi (Taiwan) and Hong Kong. Based on the AERONET data, with background AOD levels the selected temperate cities had similar clear-sky PET values especially during summertime, due to their locations at similar latitudes. This also applied to the sub-tropical cities. Increase in the AOD level to the seasonal average one led to an increase in diffuse solar radiation and in turn an increase in PET for people living in all the cities. However, the heavy aerosol loading environment in Beijing and Seoul in summertime (AODs > 3.0 in episodic situations) reduced the total radiative flux and thus PET values in the cities. On the contrary, relatively lower episodic AOD levels in Chiayi and Hong Kong led to strong diffuse and still strong direct radiative fluxes and resulted in higher PET values, relative to those with seasonal averaged AOD levels. People tended to feel from “hot” to “very hot” during summertime when the AOD reached their average levels from the background level. This implies that in future aerosol effects add further burden to the thermal environment apart from the effects of greenhouse gas-induced global warming. Understanding the interaction between ambient aerosols and outdoor thermal environment is an important first step for effective mitigation measures such as urban greening to reduce the risk of human heat stress. It is also critical to make cities more attractive and enhancing to human well-being to achieve enhancing sustainable urbanization as one of the principal goals for the Nature-based Solutions. © 2017 Elsevier Ltd

Link: https://doi.org/10.1016/j.envres.2017.07.036

Actions: Well-being in Urban Areas

Goals: Sustainable Urbanisation in cities

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The valuation of urban water management practices and associated nature-based solutions (NBS) is highly contested, and is becoming increasingly important to cities seeking to increase their resilience to climate change whilst at the same time facing budgetary pressures. Different conceptions of ‘values’ exist, each being accompanied by a set of potential measures ranging from calculative practices (closely linked to established market valuation techniques) – through to holistic assessments that seek to address wider concerns of sustainability. Each has the potential to offer important insights that often go well beyond questions of balancing the costs and benefits of the schemes concerned. However, the need to address – and go beyond – economic considerations presents policy-makers, practitioners and researchers with difficult methodological, ethical and practical challenges, especially when considered without the benefit of a broader theoretical framework or in the absence of well-established tools (as might apply within more traditional infrastructural planning contexts, such as the analysis of transport interventions). Drawing on empirical studies undertaken in Sheffield over a period of 10 years, and delivered in partnership with several other European cities and regions, we compare and examine different attempts to evaluate the benefits of urban greening options and future development scenarios. Comparing these different approaches to the valuation of nature-based solutions alongside other, more conventional forms of infrastructure – and indeed integrating both ‘green and grey’ interventions within a broader framework of infrastructures – throws up some surprising results and conclusions, as well as providing important sign-posts for future research in this rapidly emerging field. © 2017 Elsevier Inc.

Link: https://doi.org/10.1016/j.envres.2017.05.043

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

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

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Currently, economic development has become a dominant factor in the promotion of urban regeneration in China. This means that decision makers often overlook the impacts on the natural environment when planning urban regeneration within a region. To properly face such challenges and others that may arise, a strategy relying on Nature-Based Solutions (NBS) can enhance the physical and ecological environment of a city, while ensuring greater resilience to natural disasters, and the use of fewer resources. NBS also improves the social well-being of citizens by creating more inclusive and engaged communities. This paper reviews the literature concerning urban regeneration and natural disaster vulnerability to discuss the complex mechanisms of the interactions between natural disaster and urban regeneration. Then, the evaluation model of natural disaster vulnerability in urban area is constructed, and data envelopment analysis (DEA) model is used to assess the vulnerability of natural disasters in various regions of Chongqing. Finally, under the background of NBS, this paper puts forward the way of urban regeneration, and provides an important direction for urban regeneration to realize the sustainable development of cities. © 2017 by the authors.

Link: https://doi.org/10.3390/su9071205

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

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

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Spatial planning has to deal with trade-offs between various stakeholders’ wishes and needs as part of planning and management of landscapes, natural resources and/or biodiversity. To make ecosystem services (ES) trade-off research more relevant for spatial planning, we propose an analytical framework, which puts stakeholders, their land-use/management choices, their impact on ES and responses at the centre. Based on 24 cases from around the world, we used this framing to analyse the appearance and diversity of real-world ES trade-offs. They cover a wide range of trade-offs related to ecosystem use, including: land-use change, management regimes, technical versus nature-based solutions, natural resource use, and management of species. The ES trade-offs studied featured a complexity that was far greater than what is often described in the ES literature. Influential users and context setters are at the core of the trade-off decision-making, but most of the impact is felt by non-influential users. Provisioning and cultural ES were the most targeted in the studied trade-offs, but regulating ES were the most impacted. Stakeholders’ characteristics, such as influence, impact faced, and concerns can partially explain their position and response in relation to trade-offs. Based on the research findings, we formulate recommendations for spatial planning. © 2017

Link: https://doi.org/10.1016/j.ecoser.2017.10.011

Actions: Enhancing Ecosystems' Insurance Value

Goals: Restoring Degraded Ecosystems Using NbS

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We considered the limnological literature for an overview of biomanipulation methods that were implemented to avoid or reduce cyanobacterial bloom development in ponds and lakes. For this purpose, we reviewed 48 publications representing 34 whole-lake and large-scale case studies of different biomanipulation approaches clearly mentioning the extent of a cyanobacteria bloom problem and the cyanobacteria taxa involved. This delivered complementary information to the suite of review papers already providing elaborated syntheses on biomanipulation and associated ecotechnological measures as a restoration tool for overall eutrophication reduction and control. We considered nature-based solutions such as fish removal and associated water drawdown, addition of piscivorous fish, filter-feeding planktivorous fish, Daphnia or bivalves, re-introduction of macrophytes and a combination of accompanying restoration methods. Reasons for success or failure to control cyanobacterial blooms of especially Anabaena,Pseudanabaena, Aphanizomenon, Aphanocapsa, Limnothrix, Microcystis, Oscillatoria or Spirulina spp. could be explained through bottlenecks encountered with fish removal, stocking densities, cascading effects, associated zooplankton grazing, diet shifts away from cyanobacteria, macrophyte recovery, nutrient or pH status. Threshold values to avoid failures are synthesized from experiments or monitoring studies and presented in a conceptual scheme about cyanobacteria reduction through (1) direct abatement of existing blooms and forcing/maximization of biotic key interactions (2) reducing risk of blooms and improving lake or pond multi-functionality and (3) avoiding blooms, balancing biotic communities and enhancing existing ecosystem services. More information will be required on temporal dynamics and abundances of cyanobacteria taxa in whole-lake pre- and post-biomanipulation conditions to better evaluate the applicability and effectiveness of such nature-based solutions. © 2015, Springer Science+Business Media Dordrecht.

Link: https://doi.org/10.1007/s10452-015-9548-x

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

Goals: Restoring Degraded Ecosystems Using NbS

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Link: https://doi.org/10.1080/14649357.2016.1158907

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

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

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Environmental protection issues and the monitoring of pollution, especially for the largest cities in Asia, are becoming increasingly prominent factors for inclusive urban planning of public open spaces. Recently, a walkability concept was implemented in many cities, and in 2016 it became a campaign direction for development in Seoul. This paper considers conditions of implementation for the walkability concept, using examples of pedestrian walkway-making initiatives, and regeneration of existing walkways along water streams in urban case studies in Seoul, South Korea. The role of nature-based solutions was considered in relation to aesthetics, and social and environmental characteristics (e.g., air pollution, oxygenation through greenery) obtained through literature reviews for the case studies. Considering the complexity of the situation, with factors such as Air Quality Index (AQI) warning conditions, and the general positive impact of walkability on enhancing a healthy life style and social interaction and on reducing congestion, this study contributes to the discussion on walkability, and the importance of nature-based urban regeneration projects for densely populated areas in cities. The results of particular cases in this paper suggest the need for careful monitoring and consideration of various factors for urban regeneration walkable design projects. © 2017 by the authors.

Link: https://doi.org/10.3390/su9040587

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

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

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Background Quantifying carbon (C) dioxide exchanges between ecosystems and the atmosphere and the underlying mechanism of biophysical regulations under similar environmental conditions is critical for an accurate understanding of C budgets and ecosystem functions. Methods For the first time, a cluster of four eddy covariance towers were set up to answer how C fluxes shift among four dominant ecosystems in Mongolia – meadow steppe (MDW), typical steppe (TPL), dry typical steppe (DRT) and shrubland (SHB) during two growing seasons (2014 and 2015). Results Large variations were observed for the annual net ecosystem exchange (NEE) from 59 to 193 g C m− 2, though all four sites acted as a C source. During the two growing seasons, MDW acted as a C sink, TPL and DRT were C neutral, while SHB acted as a C source. MDW to SHB and TPL conversions resulted in a 2.6- and 2.2-fold increase in C release, respectively, whereas the TPL to SHB conversion resulted in a 1.1-fold increase at the annual scale. C assimilation was higher at MDW than those at the other three ecosystems due to its greater C assimilation ability and longer C assimilation times during the day and growing period. On the other hand, C release was highest at SHB due to significantly lower photosynthetic production and relatively higher ecosystem respiration (ER). A stepwise multiple regression analysis showed that the seasonal variations in NEE, ER and gross ecosystem production (GEP) were controlled by air temperature at MDW, while they were controlled mainly by soil moisture at TPL, DRT and SHB. When air temperature increased, the NEE at MDW and TPL changed more dramatically than at DRT and SHB, suggesting not only a stronger C release ability but also a higher temperature sensitivity at MDW and TPL. Conclusions The ongoing and predicted global changes in Mongolia likely impact the C exchange at MDW and TPL more than at DRT and SHB in Mongolia. Our results suggest that, with increasing drought and vegetation type succession, a clear trend for greater CO2 emissions may result in further global warming in the future. This study implies that diverse grassland ecosystems will respond differently to climate change in the future and can be seen as nature-based solutions (NBS) supporting climate change adaptation and mitigation strategies. © 2017 Elsevier Inc.

Link: https://doi.org/10.1016/j.envres.2017.08.001

Actions: Carbon Sequestration

Goals: Climate Change Adaptation and Mitigation

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Aquaponics is an integrated system in which the water containing fish waste is used as a nutrient source for plant production in a closed recirculation system. In this study, tilapia (Oreochromis niloticus) and pak choi (Brassica chinensis) culture was tested using two techniques: 1) Root floating (RAFT), and 2) Dynamic root floating (DRFT). Water quality parameters, total ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and phosphate were measured. At the end of the experiment, fish and plants were weighed and the required electric power consumption was calculated. There was no significant difference observed between the effect of each treatment group on either tilapia or pak choi production. Tilapia productivity was 1.69 ± 0.22 kg/m3 and 1.71 ± 0.23 kg/m3 and pak choi yield was 7.43 ± 1.23kg/m2 and 7.32 ± 0.76 kg/m2 for the RAFT and DRFT, respectively. Water quality parameters were within the recommended range for the tilapia culture while pH and conductivity were out of range for the pak choi culture; nevertheless, plant production was good. Total ammonia nitrogen and nitrite nitrogen did not reach concentrations that could impede tilapia growth. The DRFT allows the elimination of active aeration in hydroponic systems for tilapia and pak choi production during most of the cycle, reducing the electric power consumption to 10.3% and electricity costs to 11.4% by using a nature-based solution. © 2018 Elsevier Ltd

Link: https://doi.org/10.1016/j.jclepro.2018.02.086

Actions: Enhancing Ecosystems' Insurance Value, Sustainable use of Matter & Energy

Goals: Restoring Degraded Ecosystems Using NbS

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Nature-based solutions, such as living shorelines, have the potential to restore critical ecosystems, enhance coastal sustainability, and increase resilience to natural disasters; however, their efficacy during storm events compared to traditional hardened shorelines is largely untested. This is a major impediment to their implementation and promotion to policy-makers and homeowners. To address this knowledge gap, we evaluated rock sill living shorelines as compared to natural marshes and hardened shorelines (i.e., bulkheads) in North Carolina, USA for changes in surface elevation, Spartina alterniflora stem density, and structural damage from 2015 to 2017, including before and after Hurricane Matthew (2016). Our results show that living shorelines exhibited better resistance to landward erosion during Hurricane Matthew than bulkheads and natural marshes. Additionally, living shorelines were more resilient than hardened shorelines, as they maintained landward elevation over the two-year study period without requiring any repair. Finally, rock sill living shorelines were able to enhance S. alterniflora stem densities over time when compared to natural marshes. Our results suggest that living shorelines have the potential to improve coastal resilience while supporting important coastal ecosystems. © 2018 by the Ecological Society of America

Link: https://doi.org/10.1002/eap.1722

Actions: Coastal Resilience

Goals: Risk Management and Resilience

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