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31.
珠江河口近期岸线演变及其原因 总被引:1,自引:0,他引:1
基于不同时段的珠江河口卫星遥感图像,结合遥感-地理信息系统(RS-GIS)集成技术定量计算分析岸线近期的冲淤变化。从海平面上升和上游来沙等自然演变条件及人类工程活动两大方面分析珠江河口岸线冲淤演变的原因。结果显示:在1976—2006年,珠江河口近岸岸线整体向海淤涨579.2 m,年均淤涨19.3 m,而外海岛屿岸线总共淤涨21.6 m,年均淤涨0.7 m,近岸岸线的淤涨速率远快于自然演变过程。自然条件变化如海平面上升,在河口岸线剧烈的变化中影响较小。20世纪90年代期间上游来沙的减少与岸线淤涨速率变快的结果并不一致。详细的对比分析说明珠江河口地区的土地围垦是其岸线剧烈变化的主要因素。 相似文献
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针对浅滩吹填工程中因吹距远、水深较浅等工况条件限制,绞吸船难以在施工效率、进度、成本等方面发挥自身优势的问题,以北海铁山港的陆域吹填施工为例,通过对小型吹沙船联合施工可行性的研究及实践,得出八爪船-皮带船联合施工适合浅滩吹填的结论,并介绍联合施工的工法、工序及重难点控制。 相似文献
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John Clark 《Coastal management》2013,41(1):103-108
Abstract Analysis of recent substantive coastal land use management laws shows that their main thrust is to provide for protection of the coastal environment from adverse impacts of uncontrolled development. The four purposes cited most frequently among laws of 17 states were: Protection of wildlife and fisheries, protection of ecosystems or the natural environment, control of development, and enhancement of esthetic values. Other purposes were to: Protect life and property, enhance public recreation, conserve soil, and protect water resources. Development and economic purposes were cited in relatively few laws. 相似文献
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Paul Van Seters 《Coastal management》2013,41(2):253-273
Abstract In June 1987, the U.S. Supreme Court in Nollan v. California Coastal Commission held against the California Coastal Commission. Did this legal landmark signal the rise of a new, conservative jurisprudence of takings? And if yes, did that imply the demise of what had been accomplished by the so‐called quiet revolution in land use control that swept the country in the late 1960s and early 1970s? The complexities of this case cannot be understood apart from the historical evolution of the Coastal Commission's policies through the 1970s and 1980s, particularly its coastal access policies. Because of these policies the Coastal Commission, since its inception in 1972, has been subjected to all kinds of criticism, but at the same time has been widely praised for its balanced approach. These varying assessments of the role and record of the Commission also underly the conflicting viewpoints and arguments of Justices Scalia, who wrote for the majority in Nollan, and Brennan, who filed an extremely strong dissent. The resulting legal uncertainties, added to the political setbacks suffered from a lukewarm legislature and a hostile governor, forced the Commission to temper its assertive mission of maximizing coastal access, at least for the time being. 相似文献
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Robert Cervero 《Transportation》1996,23(4):373-394
Neo-traditional designs, proponents argue, reduce dependency on the automobile and provide attractive environments for walking, bicycling, and transit riding. This paper explores the extent to which this proposition holds for seven traditional neighborhoods in the San Francisco Bay Area that evolved around early streetcar services. Matched-pair comparisons of modal shares and trip generation rates for work trips are made between these neighborhoods and newer auto-oriented suburbs, controlling for the effects of income and, to a lesser extent, existing bus service levels. Pedestrian/bicycle modal shares and trip rates tended to be considerably higher, in some cases five time as high, in transit-oriented than in the paired auto-oriented neighborhood. Transit neighborhoods also averaged around 70 more daily transit work trips per 1,000 households than auto-oriented neighborhoods, though trip rates varied considerably among neighborhood pairs. Higher residential densities were also found to have a proportionately greater impact on transit commuting in transit-oriented than in auto-oriented neighborhoods. The paper concludes that in order to yield significant transportation benefits, neo-traditional development must be coordinated with larger regional planning efforts and public policy initiatives to reduce automobile dependency. 相似文献
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