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31.
基于HJ-1A高光谱的黄河口碱蓬和柽柳盖度反演模型研究 总被引:1,自引:2,他引:1
碱蓬和柽柳是黄河口湿地典型的盐生植物类型,是多种保护珍禽的主要栖息地,具有景观尺度较小、分布广且多混生的特点。应用覆盖黄河口北部潮滩的HJ-1A高光谱遥感影像,基于现场测量的端元光谱和从遥感影像中使用顺序最大角凸锥法(SAMCC)自动提取的端元光谱,应用线性光谱分解法(LSU)、正交子空间投影法(OSP)、匹配滤波法(MF)、最小能量约束法(CEM)和自适应一致估计法(ACE)5种不同光谱解混方法进行混合像元光谱解混,对比两种方法得到的端元光谱分别对碱蓬和柽柳盖度的反演能力,并给出相应的反演模型。结果显示:(1)现场测量端元光谱取得了较好的碱蓬和柽柳盖度反演结果,其中应用LSU方法的光谱解混结果与现场测量盖度的决定系数对于碱蓬和柽柳分别达到了0.88和0.95;(2)两种端元获取方式的光谱解混结果中,LSU和OSP方法均获得了较高的相关性,ACE解混方法的相关性都最低;(3)SAMCC方法提取端元光谱对柽柳的分解结果与现场测量盖度的相关性远高于碱蓬。 相似文献
32.
徐一剑 《气候变化研究进展》2020,16(1):88-98
我国沿海地区战略地位十分重要,并呈现“区域发展沿海化,沿海城市临海化”的趋势,但同时却面临着全球气候变化引起的海平面上升、极端气候灾害频发等诸多严峻挑战。为在战略层面解决我国向海发展的战略与全球气候变化的矛盾与冲突,文中提出了我国沿海城市应对气候变化的发展战略:确定了总体目标是建设适合我国国情的沿海气候弹性城市,提出了“规划引领、陆海统筹、主动适应、积极减排、适度冗余、增加弹性”的应对原则,明确了强化城市规划管控、控制空间发展方向、严控围填海造地、优化城市空间布局、提高规划设计标准、加强海岸防护设施、夯实城市基础设施和提升监测预警应急等8项重点任务。 相似文献
33.
34.
Quantitative assessment of vulnerability is a core aspect of wetland vulnerability research. Taking Baiyangdian (BYD) wetlands in the North China Plain as a study area and using the ‘cause-result’ model, 23 representative indicators from natural, social, sci-tech and economic elements were selected to construct an indicator system. A weight matrix was obtained by using the entropy weight method to calculate the weight value for each indicator. Based on the membership function in the fuzzy evaluation model, the membership degrees were determined to form a fuzzy relation matrix. Finally, the ecological vulnerability was quantitatively assessed based on the comprehensive evaluation index calculated by using a composite operator to combine the entropy weight matrix with the fuzzy relation matrix. The results showed that the ecological vulnerability levels of the BYD wetlands were comprehensively evaluated as Grade II, Grade Ⅲ, Grade IV, and Grade Ⅲ in 2010, 2011-2013, 2014, and 2015-2017, respectively. The ecological vulnerability of the BYD wetlands increased from low fragility in 2010 to general fragility in 2011-2013, and to high fragility in 2014, reflecting the fact that the wetland ecological condition was degenerating from 2010 to 2014. The ecological vulnerability status then turned back into general fragility during 2015-2017, indicating that the ecological situation of the BYD wetlands was starting to improve. However, the ecological status of the BYD wetlands on the whole is relatively less optimistic. The major factors affecting the ecological vulnerability of the BYD wetlands were found to be industrial smoke and dust emission, wetland water area, ammonia nitrogen, total phosphorus, rate of industrial solid wastes disposed, GDP per capita, etc. This illustrates that it is a systematic project to regulate wetland vulnerability and to protect regional ecological security, which may offer researchers and policy-makers specific clues for concrete interventions. 相似文献
35.
36.
Chemical methods are generally chosen to monitor soil pollution but magnetic measurements proved to yield additional information at low cost and less time consumption. In this investigation, the novel use of rapid and non-destructive magnetic measurements to characterize Br levels in Xuzhou (China) urban roadside soils was reported. X-ray fluorescence spectrometry (XRF) was used to quantify Br in the soil samples. Data from 21 roadside soil samples confirm Br contamination, with a mean level of 4.36 mg kg−1 and a range of 2.4–8.7 mg kg−1. These values are higher than that of unpolluted soils in Xuzhou that averages 1.1 mg kg−1. Hierarchical clustering analysis shows Br in Xuzhou roadside soils is mainly from road traffic. Clear correlations between Br levels and simple magnetic parameters [mass specific susceptibility (χ
LF), susceptibility of anhysteretic remanent magnetization (χ
ARM), saturation isothermal remanence (SIRM)] are observed. The present study shows that these three magnetic parameters can be used as a proxy for Br levels in Xuzhou urban roadside soils. 相似文献
37.
The notion of the “urban experiment” has become increasingly prevalent and popular as a guiding concept and trope used by both scholars and policymakers, as well as by corporate actors with a stake in the future of the city. In this paper, we critically engage with this emerging focus on “urban experiments”, and with its articulation through the associated concepts of “living labs”, “future labs”, “urban labs” and the like. A critical engagement with the notion of urban experimentation is now not only useful, but a necessity: we introduce seven specific areas that need critical attention when considering urban experiments: these are focused on normativity, crisis discourses, the definition of “experimental subjects”, boundaries and boundedness, historical precedents, “dark” experiments and non-human experimental agency. 相似文献
38.
城市地表饮用水源保护研究进展 总被引:24,自引:5,他引:24
城市水资源短缺和地表饮有水污染已成为全球范围的重大问题和人类社会共同关注的焦点。城市地表饮用水源的保护已越来越受到人们的重视,它的研究应该在城市地表饮用水源的科学管理和保护中发挥重要的作用。对国内外地表饮用水源保护研究现状和地表饮用水源保护现状进行综述,同时重点分析和讨论了国内外研究存在的不足,提出城市地表饮用水源保护的未来研究重点。 相似文献
39.
Vertical turbulent fluxes of water vapour, carbon dioxide, and sensible heat were measured from 16 August to the 28 September
2006 near the city centre of Münster in north-west Germany. In comparison to results of measurements above homogeneous ecosystem
sites, the CO2 fluxes above the urban investigation area showed more peaks and higher variances during the course of a day, probably caused
by traffic and other varying, anthropogenic sources. The main goal of this study is the introduction and establishment of
a new gap filling procedure using radial basis function (RBF) neural networks, which is also applicable under complex environmental
conditions. We applied adapted RBF neural networks within a combined modular expert system of neural networks as an innovative
approach to fill data gaps in micrometeorological flux time series. We found that RBF networks are superior to multi-layer
perceptron (MLP) neural networks in the reproduction of the highly variable turbulent fluxes. In addition, we enhanced the
methodology in the field of quality assessment for eddy covariance data. An RBF neural network mapping system was used to
identify conditions of a turbulence regime that allows reliable quantification of turbulent fluxes through finding an acceptable
minimum of the friction velocity. For the data analysed in this study, the minimum acceptable friction velocity was found
to be 0.15 m s−1. The obtained CO2 fluxes, measured on a tower at 65 m a.g.l., reached average values of 12 μmol m−2 s−1 and fell to nighttime minimum values of 3 μmol m −2 s−1. Mean daily CO2 emissions of 21 g CO2 m−2d −1 were obtained during our 6-week experiment. Hence, the city centre of Münster appeared to be a significant source of CO2. The half-hourly average values of water vapour fluxes ranged between 0.062 and 0.989 mmol m−2 s−1and showed lower variances than the simultaneously measured fluxes of CO2. 相似文献
40.