City profile: Ningbo

Ningbo is located in the south-east of Yangtze River Delta by the East China Sea, 220 km south of Shanghai. The city has been an important port in East China for foreign trade since 7th century. Since 1980s, encouraged by China’s economic “open-door” policy, one of the ways the city attracted foreign investment and thus grew its economy was by establishing multi-functional economic development zones near its deep-water port. As a result, Ningbo is now one of the top ten coastal ports in the world (as measured in Twenty-Foot Equivalent Units, TEUs). Similarly, the city’s GDP per capita is approximately three times the national average. The current and historic prosperity of Ningbo is in no small way related to its geographical position, just 20 km inland from the Hangzhou estuary and the gateway to the East China Sea. It is also the approximate centre of a 1000 km2 coastal plain, at the confluence of the Fenghua and Yao Rivers, and from where the Yong River leads to the sea. However, also a result of this geographic location the city is now facing an increasing risk of coastal flooding caused by increase in urban area; climate change (increased rainfall intensity); and predicted sea-level rise. As a result both water management and current flood management practice (and related infrastructure) are under scrutiny. In addition to describing the evolution of the city, this paper focuses on the implication of current planning practices in Ningbo, which aim to ensure the sustainable development of the city both in terms of its natural resources and its expected rate of economic growth

Identifying enablers and barriers to the implementation of the green infrastructure for urban flood management: a comparative analysis of the UK and China

Climate change and urbanization are increasing the urban flood risk, which can cause adverse on socio-economic and environmental impacts. Green Infrastructure (GI) can reduce stormwater runoff and offer multiple benefits that have been initiated in the United Kingdom (UK) and China, namely Sustainable Urban Drainage Systems (SUDS) and Sponge Cities Program (SCP) respectively. Currently, the implementation of GI is restricted to small spatial (site specific) scale and facing several constraints such as financial investment and governance, that limited its fuller functions and potential. This study aims to identify the barriers and enablers for the adoption of GI by investigating SUDS and SCP in the UK and China, through twelve in-depth semi-structured interviews with stakeholders. Our results found that multiple benefits of the SUDS and SCP were identified, as the main enablers in both countries with reducing the stormwater runoff and alleviating peak discharge in the drainage system, also contributing to social well-being and climate adaptations. Some barriers found the current practices are facing challenges from financial, biophysical and socio-political circumstances in both cases. We conclude that it is beneficial to learn the comparative findings and experiences from both countries, which contributes to stakeholders for improving current GI practices, in prior to achieve more sustainable long-term deliverables

Challenges in urban stormwater management in Chinese cities: A hydrologic perspective

For managing the worsening urban water disasters in China, the Government of China proposed the concept of “Sponge City” in 2013 and initiated the strategy in 30 pilot cities from 2015. Despite the promise of the concept, there have been many challenges in implementing the “Sponge City” program (SCP). In this manuscript, we discuss the hydrology-related challenges in implementing the SCP. In particular, we consider two key challenges: (1) Determination of the “Volume Capture Ratio of Annual Rainfall” (VCRAR), as controlling urban stormwater runoff is one of the core targets of the SCP; and (2) Estimation of a proper rainfall threshold, which influences the layout of green-infrastructures in the SCP to achieve the core VCRAR target. To discuss these challenges, we consider the city of Beijing, the capital of China, as a case study. Our analysis shows that the trade-offs between the investment for the SCP and its potential economic benefits should be considered by undertaking a proper determination of VCRAR. The VCRAR estimated for Beijing from the present analysis is 0.73. This value is more reasonable than the empirical value of 0.80 that is presently used, as it can guarantee the positive rate of return on the investment. We also find that the nonstationary characteristics of rainfall data and their spatiotemporal differences are important for the estimation of the rainfall threshold in SCP. For instance, even using the daily rainfall data over a period of 30 years (1983–2012) in Beijing, as required by the National Assessment Standard, the estimated rainfall threshold of 27.3 mm underestimates the reasonable rainfall threshold that should at least be larger than 30.0 mm. Thus, the former cannot ensure the VCRAR target of 0.80. Based on these results, we offer proper approaches and key suggestions towards useful guidelines for delivering better SCP in the Chinese cities

Understanding environmental justice capital in China — a new framework to study environmental justice in contexts

Environmental justice has drew worldwide attention since the 1982 protest in USA to against duping toxic waste. In the globalization era, worldwide scholars and environmental activists are actively engaged in related studies and social movements. However, these researches and movements usually ignore the influences of local contexts on local environmental justice configurations, including related researches in China. Whilst, evidences have been provided that different forms of capital from contexts, such as economic, social, political, natural capital and cultural capital, will affect the local concept of environmental justice. That is to say environmental justice should have different discourse from what has been researched in western countries in different contexts. Thus, this research will discuss the common ground of environmental justice study framework and promote the new conceptual framework “environmental justice capital” for having a better understanding environmental justice in contexts. Additionally, the framework of “environmental justice capital” will be put in Chinese contexts as a preliminary discussion to get an initial image of environmental justice in China

Mapping the research landscape of nature-based solutions in urbanism

Nature-based solutions (NBS) are an innovative concept that mimics the processes of natural ecosystems, popularized principally in the European Union. With a substantial body of literature amassed since the term’s inception in 2015, there is a need to systematically review existing literature to identify overarching gaps and trends, according to disciplinary focus, geographic scope, and key themes, and direct future research inquiry and policy recommendations. This review consists of bibliometric analysis and thematic analysis for NBS studies in urbanism. NBS studies were found to relate strongly with other concepts of ‘Ecosystem Services’, ‘Green Infrastructure’, ‘Climate Change’, and ‘Risk management and Resilience’, which align with four major thematic goals set by the European Commission. Within NBS scholarship, various sub-themes have emerged, namely, ‘Greening’, ‘Urban Development’, ‘Water’, ‘Wellbeing’, and ‘Governance’. Furthermore, we illustrate that the amount and thematic focus of NBS research have been unevenly distributed worldwide. Analysis of emerging trends shows a recent increase in topics, such as adaptive governance of NBS, and the incorporation of social justice in sustainability transitions. Based on an assessment of extant NBS literature, we offer some recommendations for the future direction of the research fields

Spatio-temporal pattern of land degradation from 1990 to 2015 in Mongolia

Land degradation is an important environmental problem facing the world. "Land Degradation Neutrality" is one of the core indicators in the 15th goal of the "United Nations Sustainable Development Goals" for 2030. Mongolia is an important country for global land degradation. The increasingly serious land degradation has caused a direct impact on the ecosystem of the entire Mongolian plateau. We analyzed the patterns of land degradation and restoration during 1990-2010 and 2010-2015 and determined the driving forces behind the variations, by using fine resolution land cover data for the first time in Mongolia. The results showed that the spatial distribution of newly increased land degradation and restoration have a strong transitional nature. For the past 25 years, the trend of land change in Mongolia was dominated by land degradation. However, land degradation was accompanied by ongoing restoration of some land areas, and the capacity for land restoration has been gradually improved. This study discovers a series of typical land degradation and restoration regions and provides an interpretation of the driving forces in these areas. The joint effects of natural and socioeconomic factors have been found to result in land degradation and restoration in different regions

Correlation-aided method for identification and gradation of periodicities in hydrologic time series

Identification of periodicities in hydrological time series and evaluation of their statistical significance are not only important for water-related studies, but also challenging issues due to the complex variability of hydrological processes. In this article, we develop a “Moving Correlation Coefficient Analysis” (MCCA) method for identifying periodicities of a time series. In the method, the correlation between the original time series and the periodic fluctuation is used as a criterion, aiming to seek out the periodic fluctuation that fits the original time series best, and to evaluate its statistical significance. Consequently, we take periodic components consisting of simple sinusoidal variation as an example, and do statistical experiments to verify the applicability and reliability of the developed method by considering various parameters changing. Three other methods commonly used, harmonic analysis method (HAM), power spectrum method (PSM) and maximum entropy method (MEM) are also applied for comparison. The results indicate that the efficiency of each method is positively connected to the length and amplitude of samples, but negatively correlated with the mean value, variation coefficient and length of periodicity, without relationship with the initial phase of periodicity. For those time series with higher noise component, the developed MCCA method performs best among the four methods. Results from the hydrological case studies in the Yangtze River basin further verify the better performances of the MCCA method compared to other three methods for the identification of periodicities in hydrologic time series

Widespread occurrence of microplastics in marine bays with diverse drivers and environmental risk

Microplastic contamination in the sediment of marine bays has attracted widespread attention, whereas the distribution, sedimentation, morphology and risk of microplastics at regional scale remain poorly understood. By introducing a data mining framework into microplastic research, we compiled a microplastic dataset of 649 samples from 24 bays to enhance the understanding of geographical difference and drivers, transfer, composition profile and environmental risk of sedimental microplastics. Microplastic abundance varied from 0.72 to 1963.96 items/kg dry weight, with higher concentrations mainly occurring in East Asian bays. The spatial pattern in abundance was driven by the river plastic emissions, aquaculture production and hydrodynamic condition. A significantly positive correlation between microplastic abundance in water and sediment was found, and microplastic sedimentation was related to polymer density, hydrodynamic conditions and sediment properties. The dominant shape and polymer of sedimental microplastics were fiber and polypropylene, respectively, and the similarity of microplastic composition decreased with increasing geographical distance. The environmental risks of microplastics were partitioned into three classes (Rank II-Rank IV) with a two-dimensional assessment system considering the bioavailability and toxicity of microplastics, and Asian bays were identified as potential high-risk areas. To reduce the environmental risk of sedimental microplastics in bays, priority should be given to the removal of microfibers, and control measures depend on the risk classes and dominant polymers. Microplastic abundance and composition were significantly affected by methodological choices regarding sampling, pretreatment and identification, suggesting a unified methodology is essential to further enhance our knowledge on the distribution and risk of microplastics in marine bays

Addressing challenges of urban water management in Chinese sponge cities via nature-based solutions

Urban flooding has become a serious issue in most Chinese cities due to rapid urbanization and extreme weather, as evidenced by severe events in Beijing (2012), Ningbo (2013), Guangzhou (2015), Wuhan (2016), Shenzhen (2019), and Chongqing (2020). The Chinese “Sponge City Program” (SCP), initiated in 2013 and adopted by 30 pilot cities, is developing solutions to manage urban flood risk, purify stormwater, and provide water storage opportunities for future usage. Emerging challenges to the continued implementation of Sponge Cities include (1) uncertainty regarding future hydrological conditions related to climate change projections, which complicates urban planning and designing infrastructure that will be fit for purpose over its intended operating life, and (2) the competing priorities of stakeholders and their reluctance to make trade-offs, which obstruct future investment in the SCP. Nature-Based Solutions (NBS) is an umbrella concept that emerged from Europe, which encourages the holistic idea of considering wider options that combine “Blue–Green” practices with traditional engineering to deliver “integrated systems of Blue–Green–Grey infrastructure”. NBS includes interventions making use of natural processes and ecosystem services for functional purposes, and this could help to improve current pilot SCP practices. This manuscript reviews the development of the SCP, focusing on its construction and design aspects, and discusses how approaches using NBS could be included in the SCP to tackle not only urban water challenges but also a wide range of social and environmental challenges, including human health, pollution (via nutrients, metals, sediments, plastics, etc.), flood risk, and biodiversity