.
29.Rethinking big data A review on the data quality and usage issues
ISPRS Journal of Photogrammetry and Remote Sensing, 2016, 115: 134-142
Jianzheng Liu, Jie Li, Weifeng Li*, Jianzheng Wu
Abstract: The recent explosive publications of big data studies have well documented the rise of big data and its ongoing prevalence. Different types of “big data” have emerged and have greatly enriched spatial information sciences and related fields in terms of breadth and granularity. Studies that were difficult to conduct in the past time due to data availability can now be carried out. However, big data brings lots of “big errors” in data quality and data usage, which cannot be used as a substitute for sound research design and solid theories. We indicated and summarized the problems faced by current big data studies with regard to data collection, processing and analysis: inauthentic data collection, information incompleteness and noise of big data, unrepresentativeness, consistency and reliability, and ethical issues. Cases of empirical studies are provided as evidences for each problem. We propose that big data research should closely follow good scientific practice to provide reliable and scientific “stories”, as well as explore and develop techniques and methods to mitigate or rectify those ‘big-errors’ brought by big data.
Sustainability, 2016, 8(2)
Qian Lin, Jiaying Mao, Jiansheng Wu, Weifeng Li, Jian Yang*
Abstract: The famous 0904world0964s factory09 city, Dongguan, like many other places in China, is a typical beneficiary of China0964s Reform and Opening-up Policy. However, rapid urban sprawl and economic growth are at the expense of the destruction of the local environment. Therefore, it is of great importance to establish an ecological security network for sustainable development. InVEST models, effective tools to measure sensitivity and intensity of external threats to quantify habitat value, are used to calculate habitat quality of water and land. By combining structural connectivity and the Least-Cost Path model (LCP model), in which corridors are determined based on the minimum accumulative cost path between each critical point, ecological security patterns were calculated. According to the results, the northwest region of Dongguan, having a large quantity of farmlands and water and therefore many corridors and critical patches, is the most essential area in the overall security of ecological environments, which should be protected first. If developed, it should be dominated by eco-tourism and eco-agriculture. We hope that research on the ecological network, which includes critical patches and corridors formed by greenland and rivers, will lead toward better-informed proposals for local urban planning and regional sustainable development.
27.Effects of Urban Landscape Pattern on PM2.5 Pollution A Beijing Case Study
Plos One, 2015, 10(11)
Jiansheng Wu, Wudan Xie*, Weifeng Li*, Jiacheng Li
Abstract: PM2.5refers to particulate matter (PM) in air that is less than 2.5渭m in aerodynamic diameter, which has negative effects on air quality and human health. PM2.5is the main pollutant source in haze occurring in Beijing, and it also has caused many problems in other cities. Previous studies have focused mostly on the relationship between land use and air quality, but less research has specifically explored the effects of urban landscape patterns on PM2.5. This study considered the rapidly growing and heavily polluted Beijing, China. To better understand the impact of urban landscape pattern on PM2.5pollution, five landscape metrics including PLAND, PD, ED, SHEI, and CONTAG were applied in the study. Further, other data, such as street networks, population density, and elevation considered as factors influencing PM2.5, were obtained through RS and GIS. By means of correlation analysis and stepwise multiple regression, the effects of landscape pattern on PM2.5concentration was explored. The results showed that (1) at class-level, vegetation and water were significant landscape components in reducing PM2.5concentration, while cropland played a special role in PM2.5concentration; (2) landscape configuration (ED and PD) features at class-level had obvious effects on particulate matter; and (3) at the landscape-level, the evenness (SHEI) and fragmentation (CONTAG) of the whole landscape related closely with PM2.5concentration. Results of this study could expand our understanding of the role of urban landscape pattern on PM2.5and provide useful information for urban planning.
26.Impact of Urban Green Space on Residential Housing Prices_ Case Study in Shenzhen
Journal of Urban Planning and Development, 2015, 141(4)
Jiansheng Wu, Meijuan Wang, Weifeng Li, Jian Peng, Li Huang
Abstract: Public resources such as transportation, hospitals, parks, and schools are important factors in housing prices. However, studies on property value have mainly concentrated on transportation, and few studies have focused on the effect that green space has on property values. Researchers have mainly focused on specific parks within different communities rather than parks (on a larger scale) to study the average impact of green space on housing prices. Therefore, the objective of this research is to quantify the effect of public resources on property value, especially green space, using the hedonic pricing method (HPM). This paper focuses on 71 parks within Shenzhen to make results universal. Transaction price data and the structural attributes of 6,473 dwelling units were collected. This paper looks at HPM from three dimensions: structural attributes, location variables, and environmental variables. The results showed that (1) proximity to a central business district (CBD) produced the greatest effect on housing prices, followed by distance to park, distance to school, distance to arterial road, and distance to subway; (2) proximity to a park noticeably contributes to housing prices at 0.041%, and housing prices decline at a rate of 20,920 CNY (US$3,356)/km depending on distance to the nearest park; and (3) the average influence radius of Shenzhen parks was 1.73 km, and the 71 parks could promote an increase in value across 412.14 km2 of land. This research will be helpful in residential housing purchase decision-making, for reasonable estate development layouts (for developers), and for governments (in terms of increasing environmental tax to promote green space preservation).
25. Applying land use regression model to estimate spatial variation of PM2.5 in Beijing, China
Environmental Science and Pollution Research, 2015, 22(9): 7045-7061
Jiansheng Wu, Jiacheng Li, Jian Peng, Weifeng Li, Guang Xu, Chengcheng Dong
Abstract: Fine particulate matter (PM2.5) is the major air pollutant in Beijing, posing serious threats to human health. Land use regression (LUR) has been widely used in predicting spatiotemporal variation of ambient air-pollutant concentrations, though restricted to the European and North American context. We aimed to estimate spatiotemporal variations of PM2.5 by building separate LUR models in Beijing. Hourly routine PM2.5 measurements were collected at 35 sites from 4th March 2013 to 5th March 2014. Seventy-seven predictor variables were generated in GIS, including street network, land cover, population density, catering services distribution, bus stop density, intersection density, and others. Eight LUR models were developed on annual, seasonal, peak/non-peak, and incremental concentration subsets. The annual mean concentration across all sites is 90.7 μg/m(3) (SD = 13.7). PM2.5 shows more temporal variation than spatial variation, indicating the necessity of building different models to capture spatiotemporal trends. The adjusted R (2) of these models range between 0.43 and 0.65. Most LUR models are driven by significant predictors including major road length, vegetation, and water land use. Annual outdoor exposure in Beijing is as high as 96.5 μg/m(3). This is among the first LUR studies implemented in a seriously air-polluted Chinese context, which generally produce acceptable results and reliable spatial air-pollution maps. Apart from the models for winter and incremental concentration, LUR models are driven by similar variables, suggesting that the spatial variations of PM2.5 remain steady for most of the time. Temporal variations are explained by the intercepts, and spatial variations in the measurements determine the strength of variable coefficients in our models.
24. Assessing Landscape Ecological Risk in a Mining City A Case Study in Liaoyuan City, China
Sustainability, 2015, 7(7): 8312-8334
Jian Peng*, Minli Zong, Yi'na Hu, Yanxu Liu, Jiansheng Wu
Abstract: Landscape ecological risk assessment can effectively identify key elements for landscape sustainability, which directly improves human wellbeing. However, previous research has tended to apply risk probability, measured by overlaying landscape metrics to evaluate risk, generally lacking a quantitative assessment of loss and uncertainty of risk. This study, taking Liaoyuan City as a case area, explores landscape ecological risk assessment associated with mining cities, based on probability of risk and potential ecological loss. The assessment results show landscape ecological risk is lower in highly urbanized areas than those rural areas, suggesting that not only cities but also natural and semi-natural areas contribute to overall landscape-scale ecological risk. Our comparison of potential ecological risk in 58 watersheds in the region shows that ecological loss are moderate or high in the 10 high-risk watersheds. The 35 moderate-risk watersheds contain a large proportion of farmland, and the 13 low-risk watersheds are mainly distributed in flat terrain areas. Our uncertainty analyses result in a close range between simulated and calculated values, suggesting that our model is generally applicable. Our analysis has good potential in the fields of resource development, landscape planning and ecological restoration, and provides a quantitative method for achieving landscape sustainability in a mining city.
Landscape and Urban Planning, 2015, 143: 56-68
Jian Peng*, Yanxu Liu, Jiansheng Wu, Huiling Lv, Xiaoxu Hu
Abstract: Ecosystem health assessment is always one of the key topics of ecosystem management. However, few studies has focused on assessing ecosystem health of landscapes, which are geo-spatial units composed of different kinds of ecosystem mosaics. Healthy ecosystems should sustainably provide a range of ecosystem services to meet human needs, and such a concept often cannot be expressed using the traditional ecosystem health assessment. Using Shenzhen City in China as a case study area, this research aims to assess the ecosystem health of urban landscapes based on ecosystem services. Results showed a distinct deterioration of urban ecosystem health for all of the 30 units assessed in Shenzhen City during 1978â2005. Five levels were classified with respect to health using fixed thresholds. There were 12 towns appearing with the worst level and 4 towns disappearing with the best level in 2005 compared with the status in 1978. Although there was no significant decrease in the level of health during 1978â2000, by 2005 more than 70% of towns belonged to the top two levels, classifying them as unhealthy. Among all the assessing indicators, the indicators of ecosystem organization contributed least to ecosystem health, except in 1986, and ecosystem services were found to be the most contributive indicator during 1978â2005. It was also suggested that land use patterns provided an integrating bridge among regional ecosystem health, economic development, and environmental performances.
Journal of Urban Planning and Development, 2015, 141(4)
Zhe Feng, Jiansheng Wu, Yang Gao, Jian Peng
Abstract: The balance between overall economic growth and protection of the environment is an important research topic of urban sustainable development. In 2005, Shenzhen promulgated the regulations, Administrative Regulations of Shenzhen Municipality on the Essential Area for Protecting Ecology [abbreviated as essential area policy (EAP)], which limited development to protect ecology. In order to evaluate the effects of this policy, a computer model was used to simulate land-use change based on a land-use change survey dataset of Shenzhen, a typical rapid urbanization area, under four scenarios. The writers aimed at developing a clear understanding of not only the effects of land protection policies for urban ecosystems but of a well-grounded prospect for regionally coordinated development as well. Five landscape structure metrics were chosen to describe the landscape pattern, including (1) number of patches, (2) mean patch area, (3) landscape shape index, (4) aggregation index, and (5) contagion index. In calculating and comparing these landscape metrics, the results support the conclusion that facing pressure from urban sprawl, agroecological land, water, and other nature-dominated areas shrink to high-altitude regions, and many small landscape patches disappear altogether, especially in the mixed periurban region in each scenario. The rapid growth of construction zones causes landscape fragmentation and renders the shape of the urban landscape more regular and smooth. However, EAP can keep small land patches from being developed into built-up areas; improve the percentage of agroecological land, water, and other nature-dominated areas within protected zones; and impel the relocation of these kinds of land-use from outside to inside the zone. The EAP affects the landscape pattern by increasing the mean area of each patch and the number of patches. If EAP were implemented in 2008, the number of patches and the landscape shape index would be relatively higher, whereas the aggregation and contagion indices would be lower than those resulting from nonimplementation. If EAP were implemented in 2008 but abolished in 2013, the number of patches and the landscape shape index would decrease, while the aggregation and contagion indices would increase. In contrast, if EAP were implemented in 2013, the number of patches and the landscape shape index would increase, while the aggregation and contagion indices would decrease. Delimitation of the boundary of an essential area is a critical factor in designing an effective policy. This paper enables land planners to understand the effects of EAP and highlights its importance as a tool for policymakers and stakeholders.
21.MSPA-Based Urban Green Infrastructure Planning and Management Approach for Urban Sustainability: Case Study of Longgang in China
Journal of Urban Planning and Development, 2015, 141(3)
Qing Chang, Xiaowen Liu, Jiansheng Wu, Pan He
Abstract: In China, rapid city expansion and the consequent loss and fragmentation of green spaces presents a major challenge for urban planners wanting to maintain urban sustainability. The aim of this paper is to formulate a workable framework to plan and manage urban green infrastructure for urban sustainability through a case study of Longgang, a typical developed area in China. Urban green infrastructure is associated with various landscape types, which have different functional niches in a UGI network. By integrating morphological spatial pattern analysis (MSPA) into landscape ecological principles based on a geographic information system, the functional niches of landscapes were defined as core areas, connectors, islets, and three levels of potential connectors. Then a future urban green infrastructure scenario with hierarchical hubs, links, and sites was delineated. Finally, by contrasting the plan scenario and the basic ecological control line (BECL) of Longgang, some focus areas for management strategies were proposed. With this approach, green infrastructure elements are preserved first in a given region, and new greening element locations and adaptive measures are emphasized. It is hoped that this framework could be used to promote the spatial navigation of urban green-space system planning and urban sustainability in China.
20.Dynamics of Urban Density in China Estimations Based on DMSPOLS Nighttime Light Data
Ieee Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2014, 7(10): 4266-4275
Jiansheng Wu, Lin Ma, Weifeng Li, Jian Peng, Hao Liu
Abstract: In China, rapid urbanization has increased the demand for urban land and intensified the conflict between limited land resources and urban development. In response, high urban density has been proposed to realize sustainable urban development. Achieving this goal requires an examination of the dynamics of urban density in China. Nighttime light (NTL) data from the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) are a good indicator of human activity. We applied NTL data to measure urban density in 70 major cities in China during 1992-2010. Based on temporal changes in NTL, we identified seven classes of urban density and clustered the distributions of urban density in 70 cities into six types. The dynamics of urban density were then obtained from the GDP density as an index of city development. The curves of urban density distribution gradually changed from a concave increase to W-shaped and S-shaped to a concave decrease, indicating that the current urban land use in China is unsustainable and that the shortage of land resources must be addressed. An examination of the distribution of urban density in Hong Kong revealed a different pattern and a potential solution for cities in mainland China.
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