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Burghard W. Flemming 《Sedimentary Geology》2007,202(3):425-435
To this day, deterministic physical models capable of explaining the evolution of grain-size distributions in the course of transport are still lacking. For this reason, various attributes of particle frequency distributions, in particular curve shapes and textural parameters, have for many decades been investigated for potential information about transport behaviour and size-sorting processes of sediments in numerous environments. Such approaches are essentially conceptual and hence rely heavily on the validity of the assumptions on which they are based. A factor which has to date been largely ignored in this context, is the fact that different methods of grain-size analysis (e. g. sieving, laser absorption and diffraction, settling velocity measurements), when applied to the same sample material, produce variable curve shapes, and hence incongruous textural data. This is illustrated by selected examples showing the differences between sieving and settling results, conversion of settling velocities into equivalent settling diameters (psi-phi-transformations), and the influences of particle shape, particle density, and water temperature. It is demonstrated that particle-size distributions are not only method-dependent but also dependent on the adopted post-processing procedure. As a result, only frequency curves generated by the same method and subsequently processed by identical computational procedures can be meaningfully compared. Furthermore, the computation of textural parameters from bi- or multimodal size distributions produces spurious results which are unrelated to the processes leading to the mixing of different size populations frequently observed in nature. In such cases, only the decomposition of such distributions into individual populations and the spatial comparison of such populations makes any sense. Because a physical explanation for the generation of size distributions is lacking, a particular curve shape of a grain-size population has no meaning on its own. Only a systematic comparison of progressively changing curve shapes (and associated textural parameters) of sediments collected on a closely spaced grid can yield data suitable for sediment trend analysis. 相似文献
24.
上海城市游憩者流动行为研究 总被引:165,自引:9,他引:165
由参与游憩活动的本地居民和外来游客共同构成城市游憩者。城市游憩者在空间上的流动规律将影响城市游憩设施和旅游资源的开发管理。通过旅行测定手段获得基本数据,运用游憩活动空间和使用曲线分析技术,研究上海城市游憩者的流动规律。 相似文献
25.
瞬态面波技术在冲洪积层勘察中的应用 总被引:2,自引:0,他引:2
瞬态面波技术具有速度快、精度高、对场地要求低等特点。采用适宜的工作参数和技术方法,在冲洪积层勘察中可较好地了解其物质分布,从而进行场地土类划分及评价、饱和砂土液化分析等,为设计、施工提供各层位物理力学指标等参数,亦为抗震设计提供场地卓越周期等资料,补充和丰富工程勘察资料,提高精度,缩短工程周期。 相似文献
26.
北京市经济增长与环境污染水平计量模型研究 总被引:171,自引:10,他引:171
选取北京市 1985~ 1999年经济与环境数据 ,通过分析经济因子与环境因子相互关系 ,探究北京市经济增长与环境质量演替轨迹 ,以建立北京市经济增长与环境污染水平计量模型 ,为评价北京市环境政策提供依据。实证研究表明 :北京市自 1985年以来随着经济增长其环境恶化程度在下降 ,且已进入经济与环境协调发展后期阶段。北京市各环境指标与人均GDP演替轨迹呈现显著的环境库兹涅茨曲线特征 ,但比发达国家较早实现了其环境库兹涅茨曲线转折点 ,且到达转折点的时间跨度小于发达国家。这主要归功于中国及北京市政府近 10年来 ,尤其 1995年以来有效环境政策和巨额环境投资以及科技后发优势。 相似文献
27.
Relationship between economic growth and water environmental quality of Anshan city in Northeast China 总被引:1,自引:0,他引:1
Based on the decomposition model of environmental quality and univariate regression model, the relationships of industrial wastewater drainage with economic scale, economic structure, and technological level in Anshan, a mining city in Northeast China, were studied. The results showed that, due to scale effect, the drainage of three important industrial wastewater pollutants (COD, NH3-N and petroleum) increased 8505t, 671t and 384t, respectively, and due to structure effect, those pollutants drainage increased 3996t, 174t and 120t from 2001 to 2006. While due to technological effect, the drainage of COD, NH3-N and petroleum reduced 4452t, 458t and 331t, and due to cross effect, those pollutants drainage reduced 7270t, 575t and 476t simultaneously. Meantime, the relationships between household consumption structure and domestic sewage discharge were analyzed, and domestic sewage discharges in different income levels were also compared. The results showed that, the domestic sewage discharges would increase 376t with 1000 yuan (RMB) increased in the traffic and communication consumption, and they would be 344t, 219t, 428t, 1873t, respectively, in housing consumption, food consumption, medical consumption, miscellaneous commodity consumption. The proportion of domestic sewage discharge increased for high income residents significantly, but reduced for lower income residents. The industrial wastewater pollutants drainage tends to be reduced by technical progress, while domestic sewage discharge will be a more important factor for urban water environment quality. 相似文献
28.
江苏省工业废水排放与经济增长的动态关系 总被引:8,自引:0,他引:8
本文研究了1980~2004年江苏省工业废水排放与经济增长的动态关系,结果表明1980年以来江苏省工业废水排放量在波动中平缓增长,排放强度不断下降,主要来源于制造业和能源生产部门,南京市、苏南三市和苏中苏北九市的排放量大致各占排放总量的1/3。采用环境库兹涅茨曲线模型模拟了1980~1996年和1997~2004年工业废水排放量和人均GDP之间的关系,结果显示未来江苏省工业废水排放趋向于在经历较短时间的上升后逐渐下降。采用分解分析方法分析了三种效应在工业废水排放变化中的贡献率,结果表明广义技术效应、规模效应是影响工业废水排放的重要因素,但广义技术效应起到决定性的作用。 相似文献
29.
基于Weibull函数和Gamma函数的环境污染与经济增长的关系 总被引:4,自引:1,他引:3
环境库兹涅茨曲线是研究环境污染与经济增长之间关系的有效工具。传统的环境库兹涅茨曲线研究大多采用线性模型或对数线性模型,其在采用模型描述关系的问题上存在一定的不足。为克服这些不足,本文采用Weibull函数和Gamma函数形式的面板数据模型对中国29个省区1989~2005年四种环境污染指标人均排放量与人均收入之间的关系予以研究。结果表明Weibull函数和Gamma函数的面板数据模型拟合效果较好,且参数具有较好的解释能力;人均废水和人均SO2都随人均收入增加先上升后减少,在25000元附近出现结构转变点,而人均固体废弃物和人均废气随人均收入增加则呈现单调增加的变化趋势,没有出现结构转变点。 相似文献
30.
Remote sensing and GIS for artificial recharge study, runoff estimation and planning in Ayyar basin, Tamil Nadu, India 总被引:4,自引:0,他引:4
This paper focuses on artificial groundwater recharge study in Ayyar basin, Tamil Nadu, India. The basin is covered by hard crystalline rock and overall has poor groundwater conditions. Hence, an artificial recharge study was carried out in this region through a project sponsored by Tamil Nadu State Council for Science and Technology. The Indian Remote Sensing satellite 1A Linear Imaging Self Scanning Sensor II (IRS 1A LISS II) satellite imagery, aerial photographs and geophysical resistivity data were used to prioritize suitable sites for artificial recharge and to estimate the volume of aquifer dimension available to recharge. The runoff water available for artificial recharge in the basin is estimated through Soil Conservation Service curve number method. The land use/land cover, hydrological soil group and storm rainfall data in different watershed areas were used to calculate the runoff in the watersheds. The weighted curve number for each watershed is obtained through spatial intersection of land use/land cover and hydrological soil group through GeoMedia 3.0 Professional GIS software. Artificial recharge planning was derived on the basis of availability of runoff, aquifer dimension, priority areas and water table conditions in different watersheds in the basin. 相似文献