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261.
潮汐站资料分析表明香港地区海平面每年以1mm的速度上升。然而,在沿海填海地区,由于受长期地面沉陷的影响,下沉速度超过上升速度,导致海平面明显相对上升。受大规模地面沉陷的影响。填海区在台风暴潮期间极易受海水浸淹。为了有助于未来海岸的开发,建议利用现有技术水平的测量方法,包括卫星测高和激光测距方法等,对填海区进行长期连续的地面沉陷监测。对下沉问题提出预警,以便采取措施,如修筑海提,建抽水站等,以抵御海 相似文献
262.
全球变化对农业的影响及适应对策 总被引:7,自引:0,他引:7
政府间气候变化专门委员会是为气候变化框架公约提供科学和技术评价的机构,下设负责气候和温室气体、影响和对策、社会和经济问题三个工作组。它的第一次评价报告完成于1990年,修订于1992年。为了于1995年9月完成它的第二次评价报告,IPC组织了世界各国200多名各领域的科学家(13名来自中国)分50多个章节撰写,于1995年3月完成了IPCC第二次评价报告的第三稿。本文浓缩介绍了IPCC第二工作组D 相似文献
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265.
南极晚更新世40,000年B.P.和在20,000年B.P.间曾有两次海侵,当时的海面比现在高6-35m。在18,000年B.P.全球低海面时,中国南极长城给所在的南设得兰群岛为一相连大岛,当时的海面比现在低100-130m。冰后期南极海面上升,在6,000年B.P.为高海面,当时海面比现在高2m。随后的6,000年以来,南极处于地壳均衡上升阶段,形成海拔20m以下连续发育的海岸阶地。 相似文献
266.
Entropy principles in the prediction of water quality values at discontinued monitoring stations 总被引:1,自引:0,他引:1
A new methodology for predicting water quality values at discontinued water quality monitoring stations is proposed. The method is based upon the Principle of Maximum Entropy (POME) and provides unbiased predictions of water quality levels at upstream tributaries and on the mainstem of a river given observed changes in the distribution of the same water quality parameter at a downstream location. Changes in the values of water quality parameters which are known a priori to have occurred upstream, but which are not sufficiently large to account for all the observed change in the same water quality parameter at the downstream location are able to be incorporated in the method through the introduction of a new term in the basic entropy expression. Application of the procedure to water quality monitoring on the Mackenzie River in Queensland, Australia indicates the method has considerable potential for prediction of water quality at discontinued stations. The method also has potential for identifying the location of causes of observed changes in water quality at a downstream station. 相似文献
267.
Peterson James T. Komhyr W. D. Waterman L. S. Gammon R. H. Thoning K. W. Conway T. J. 《Journal of Atmospheric Chemistry》1986,4(4):491-510
The first 10 years (1973–1982) of atmospheric CO2 measurements at Barrow, Alaska, by the NOAA/GMCC program are described. The paper updates and extends the Barrow CO2 record presented in Tellus (1982). The data are given in final form, based on recent calibrations of the Scripps Institution of Oceanography, with selected values identified as representative of large, spacescale conditions. Analyses of the data show: (1) a long-term CO2 average increase of 1.3 ppm per year, but with large year-to-year variations in that growth rate; (2) a suggestion, not statistically significant, of a secular increase in the amplitude of the annual cycle, presumably a reflection of global-scale biospheric variability; and (3) good absolute agreement between the Barrow results and those from four neighboring high latitude sites between 50 and 82°N. 相似文献
268.
Kahak salt playa in South Khorasan province of Iran, have special geomorphological characteristics by the presence of ephemeral saline lakes, wetlands, salt crusts, surface accumulations of salt and zones of patterned ground. Salt crusts in the soil surface are unique in the region and have laminated horizons in the playa soil. Soil-surface salt accumulations are dominated by NaCl and gypsum. It has been found that distribution of chemical soluble is not uniform across the playa landscape, and this result influences on the variety form of patterned ground. In this study, the percent changes in some of the chemical elements such as NaCl, gypsum and also brine extent have been calculated in the playa. Indicating changes in Kahak salt playa is the main aim of this study by using remote sensing and GIS techniques. In this paper, techniques such as spectral un-mixing, maximum likelihood classification, band rationing, fuzzy classification and correlation relationships are discussed. This contribution presents modeling of temporal and spatial changes of salinity and playa developing using combined approaches that incorporate different data-fusion and data-integration techniques for two periods of date. Furthermore, percent changes in the surface-patterned ground of the playa have been calculated using texture and pattern analysis of the PCA1. Results have revealed that, in the playa developing, chemical materials such as sodium, NaCl, gypsum and also brine extent are positively correlated with each other and the most increased changes are related to gypsum and the most decreased changes are related to the NaCl. Also changes in the amount of agricultural area in the playa-lakes margin, show low effects in the desertification process. 相似文献
269.
Categorical maps, comparisons, and confidence 总被引:2,自引:0,他引:2
The comparison of categorical maps is a common problem in several different contexts. Differences between categorical maps can be characterized and measured in a variety of ways. In 2004 we invited individuals from remote sensing, geographical information analysis, spatial modelling, and landscape ecology to participate in a virtual workshop in order to compare strategies for comparison. This revealed that the key dimensions of comparison relate to (1) the map characteristics considered, (2) the nature of the comparison, (3) the handling of geographical space, (4) the units of computed measures, and (5) the tests of significance.Ferko Csillag deceased 相似文献
270.