GPS用于滑坡监测的试验与研究   总被引：12，自引：0，他引：12  

徐绍铨  李英冰 《全球定位系统》2003,28(1):2-8

通过三峡库区滑坡GPS监测（静态相对定位），龙羊峡水库近岸滑坡GPS监测（快速静态相对定位）的试验，结果表明，GPS完全可以代替常规的监测方法，用于滑坡监测领域。  相似文献   

中国沿海造船工业发展与展望   总被引：3，自引：0，他引：3  

张耀光  董丽晶  李春平 《地域研究与开发》2003,22(2):16-20

中国是古老的造船国家，目前已发展成为世界第三大造船国，是具有船舶产量发展速度快、技术含量高、具备国际性产业基本特征的工业部门。文章分析了我国造船工业分布的现状特征、存在问题与差距。对我国造船工业特别是在加入WTO后，如何进一步发展，提出了措施与对策。  相似文献   

我国西南岩溶地区土地石漠化研究   总被引：21，自引：0，他引：21  

李林立  况明生  蒋勇军 《地域研究与开发》2003,22(3):71-74

在西南地区分布着以贵州为中心的、面积约54万km^2的碳酸盐岩山区，它是我国喀斯特地貌最发育的地区。同时也是石漠化最严重的地区。石漠化的产生与发展既有自然方面的原因，又有人为方面的原因，究其根本原因，是其岩溶生态系统中土壤这个关键因子的脆弱性所致。文章试图从土壤这个角度来全新阐述石漠化的成因及防治对策  相似文献   

The influence of the coast on the dynamics of upwelling fronts: Part I. Laboratory experiments     

Pascale Bouruet-Aubertot  P. F. Linden 《Dynamics of Atmospheres and Oceans》2002,36(1-3)

We describe laboratory experiments on the instability and later evolution of a front in a two-layer rotating fluid. In particular, we focus on the influence of a nearby boundary on instability growth and eddy formation. The front is produced through the adjustment of a buoyant fluid initially confined within a bottomless cylinder. Typically a front in quasi-cyclostrophic balance establishes after two rotation periods, after which it becomes unstable. Measurements of the velocity and vorticity fields at the surface are made which provide detailed information on the evolution of the front as the instability grows to finite amplitude. We focus on the time evolution of the vorticity and distinguish between the cyclonic and anticyclonic components. The spatial averages of the cyclonic and anticyclonic vorticity first grow exponentially. This growth saturates when eddies form and are advected across the front. The growth rate depends upon two nondimensional parameters: the width W of the upwelling region in units of the internal radius of deformation and the depth ratio δ between the two layers. Measurements of the growth rates for the average of the cyclonic and anticyclonic vorticity are compared to the values inferred from a simplified model for baroclinic instability. A good agreement is obtained when the front develops far from the boundary (i.e. W1). However, the agreement is only qualitative when the front is near the boundary (i.e. W1). We find that, as W decreases, the growth of cyclonic eddies consisting of dense—“coastal”—water is enhanced compared to that of anticyclonic vorticity consisting of buoyant—“off-shore”—water. This crucial effect of the boundary with respect to the instability of the front has significant impact on exchanges across the front.  相似文献   

Sedimentation in a fluvially infilling, barrier-bound estuary on a wave-dominated, microtidal coast: the Ouémé River estuary, Benin, west Africa     

Edward J. Anthony  Lucien M. Oyéd醠 Jacques Lang‡ 《Sedimentology》2002,49(5):1095-1112

The Ouémé River estuary is located on the seasonally humid tropical coast of Benin, west Africa. A striking feature of this microtidal estuary is the presence of a large sand barrier bounding a 120 km² circular central basin, Lake Nokoué, that is being infilled by heterogeneous fluvial deposits supplied by a relatively large catchment (50 000 km²). Borehole cores from the lower estuary show basal Pleistocene lowstand alluvial sediments overlain by Holocene transgressive–highstand lagoonal mud and by transgressive to probably early highstand tidal inlet and flood‐tidal delta sand deposited in association with non‐preserved transgressive sand barriers. The change in estuary‐mouth sedimentation from a transgressive barrier‐inlet system to a regressive highstand barrier reflects regional modifications in marine sand supply and in the cross‐barrier tidal flux associated with barrier‐inlet systems. As barrier formation west of the Ouémé River led to an increasingly rectilinear shoreline, the longshore drift cell matured, ensuring voluminous eastward transport of sand from the Volta Delta in Ghana, the major purveyor of sand, to the Ouémé embayment, 200 km east. Concomitantly, the number of tidal inlets, and the tidal flux associated with a hitherto interlinked lagoonal system on this coast, diminished. Complete sealing of Lake Nokoué has produced a large, permanently closed estuary, where tidal intrusion is assured through the interconnected coastal lagoon via an inlet located 60 km east. Since 1885, tides have entered the estuary directly through an artificial outlet cut across the sand barrier. Although precluding the seaward loss of fluvial sediments, permanent estuary‐mouth closure has especially deprived the highstand estuary of marine sand, a potentially important component in estuarine infill on wave‐dominated coasts. In spite of a significant fluvial sediment supply, estuarine infill has been moderate, because of the size of the central basin. Estuarine closure has resulted in two co‐existing highstand sediment suites, with limited admixture, the marine‐derived, estuary‐mouth barrier and upland‐derived back‐barrier sediments. This situation differs from that of mature barrier estuaries characterized by active fluvial‐marine sediment mixing and facies interfingering.  相似文献   

抚仙湖北岸景观生态建设   总被引：3，自引：0，他引：3  

吴献花  侯长定 《云南地理环境研究》2002,14(2):56-60

抚仙湖北岸是旅游业发展的黄金海岸，开发历史长，污染较为集中。通过对现存的主要环境问题的分析，根据流域生态学与管理学的原理，提出抚仙湖北岸景观生态建设的途径：（1）实施老环湖公路以下农田的退垦还湖，减少农田污染；（2）拆迁湖滨带居民点，消除农村污染。（3）拆除部分规模小、污染大的旅游度假设施，消除旅游污染和景观障碍。（4）建立主要人湖口经济性人工湿地，净化面源污水。（5）恢复万米沙滩，营造自然和谐的湖滨环境。（6）发展观光农业生态园，创建高原湖泊滨海旅游度假区新型模式。  相似文献   

2000年来华南沿海气候与环境变化   总被引：21，自引：3，他引：21       下载免费PDF全文

李平日  谭惠忠  侯的平 《第四纪研究》1997,17(1):86-94

通过华南沿海两个钻孔剖面的孢粉分析，并用14种热带、南亚热带木本植物花粉含量之和与5种中、北亚热带和暖温带木本植物花粉含量之和的比值作为冷热变化的温度半定量曲线；利用2000年来古籍、地方志记载的典型热带动、植物分布、兴衰的变化作冷暖变化事件；以华南沿海罕见的降雪记载，特别是对15世纪以来的降雪现象分纬度统计其出现频率，探讨华南的小冰期。据此分析华南沿海2000年来的气候和环境变化。  相似文献   

东南沿海地区旱涝气侯准周期振荡特征及其变化趋势   总被引：1，自引：0，他引：1  

蔡学湛  张容焱 《热带地理》1997,(4)

本文提出干旱指数与洪涝指数二分序列，讨论了东南沿海地区1470～1993年时间序列上旱、涝气候准周期振荡特征．结果表明，旱的周期振动与涝的周期振动存在着差异，在不同的时间尺度上都有所反映，作周期分析时有必要分别寻求旱与涝各自的周期振动分量．结果还表明，太阳活动11年周期，22年磁周期和日月地相对运动19年周期，都与该区旱涝长期变化存在着较强的统计对应关系，并且太阳活动强弱世纪周期对其长期变化也有一定的影响。  相似文献   

Pb-210 and Cs-137 distribution in Burullus lagoon sediments of Nile river delta, Egypt: sedimentation rate after Aswan High Dam     

Zhuang XU  Alaa SALEM  Zhongyuan CHEN  Weiguo ZHANG  Jing CHEN  Zhanghua WANG  Qianli SUN  Daowei YIN 《Frontiers of Earth Science》2008,2(4):434-438

This paper examines the Burullus lagoon deposits of the Nile delta coast and the distribution of Pb-210 and Cs-137. Three vibrocores from the lagoon have revealed densely concentrated shell fragments of brackish water origin in the upper (<ca. 15cm, in general) core sediments. Pb-210 and Cs-137 are in general measurable above this sediment core horizon, but, the rest downcore remains as an irregular distribution pattern, probably incurred due to secondary sediment transport or seawater seepage related processes. The present study of Pb-210 and Cs-137 and associated sediment nature of Burullus lagoon prefers sediments of <15 cm in vibrocores to after Aswan High Dam constructed in 1964, with sedimentation rate of 0.42-0.56 cm/a.  相似文献   

渤海湾西岸BZ₁钻孔的磁性地层学研究   总被引：7，自引：1，他引：6       下载免费PDF全文

肖国桥  郭正堂  陈宇坤  姚政权  邵永新  王旭龙  郝青振  卢演俦 《第四纪研究》2008,28(5):909-916

文章对位于渤海湾西岸黄骅坳陷内的BZ1钻孔进行了详细的磁性地层学研究。结果表明,204.51m的岩芯记录了布容正向极性时(Brunhes)、贾拉米洛(Jaramillo)和奥尔都维(Olduvai)极性亚时,钻孔底部年龄约为2.21Ma。本项研究结果为该区约2.21Ma以来的古环境和相关研究提供了可靠的地层年代框架。与沧县隆起区的BZ2钻孔地层结果对比表明,两个构造单元的沉积物厚度在布容期以来差异较大,即在此期间黄骅坳陷相对沧县隆起下沉40余米,表明1Ma前后发生的新构造运动导致黄骅坳陷区构造下沉速率显著增加。  相似文献