共查询到20条相似文献，搜索用时 824 毫秒
1.
2.
《Marine Policy》2005,29(3):223-234
In a previous paper on Canal management we examined the treaties and regulations underpinning firstly American and later Panamanian administration of the Canal. We also looked at the transfer of the Canal into Panamanian hands, including the management models used, ending with a review of toll structures and results. The subject of this paper is the operation of the Canal and the heated debate surrounding its modernisation, with a view to determining the adequacy of projected plans, as well as any future requirements, for maintaining its capacity in the 21 century. This paper seeks to analyse the Canal's operation, modernisation programmes and traffic systems as well as its key element: human resources. 相似文献
3.
《Marine Policy》2005,29(1):25-37
Two major components of the Panamanian economy are its maritime sector and the Canal. The author covered the analysis of the former in a previous paper. For a rigorous study on the future capacity of the Canal, it is required, on the one hand, that an analysis of its management be done and, on the other hand, of its operation, modernisation and future scope. This paper focuses on the Canal management since its creation, reviewing its historical background, legal foundations, as well as its management and toll system currently in place—which is the responsibility of Panama nationals, once the Canal was transferred by the USA. Present management indicates optimum performance and outstanding improvements. It is successfully facing the challenge of maintaining the operating capacity to accommodate future world traffic. Its operation, traffic and modernisation will be the subject of our next paper. 相似文献
4.
为研究莱州湾水交换对胶莱运河修建工程的响应,以及为海洋污染治理问题提供参考,以莱州湾为重点模拟区域建立了二维平面潮流和对流扩散模型,利用渤海、黄海、莱州湾地形及海洋环境资料,结合2018年莱州湾海水水质监测结果,初步分析了胶莱运河的修建对莱州湾海洋环境现状的影响。模拟结果表明,胶莱运河建成后年径流总量约为7.2×109 m3,净流方向由胶州湾流向莱州湾;工程后整个莱州湾水交换能力略有增强,东部强于西部,半交换周期缩短14 d;黄海海水经由胶州湾进入胶莱运河输送至莱州湾,冲淡莱州湾内非优良水体,从一定程度上缓解了莱州湾东部河口入海处小范围海域海水水质现状。 相似文献
5.
内河航运是交通运输业重要的组成部分，具有独特的优越性。京杭运河距今已有近2500年的历史，是世界上开凿最早、最长的人工运河。鲁西南地区具有丰富的煤炭、石膏等矿产资源，长江以南京杭运河南段苏浙沪水网地区，是我国重要的工业生产基地．迫切需要从北方调入大量煤炭，在津浦线运力早已饱含的情况下，京杭运河济宁至徐州段续建工程更显得十分必要。该工程包括：航道、船闸、公路桥、节制闸、港口、船厂、航修站、微波通信等项目。工程总投资14．96亿元，完工后可净增港口吞吐能力1550万t，三级航道的年货物通过能力将达4000万t．京杭运河山东段工程的续建和崛起必将为齐鲁经济和强国富民做出更大贡献。 相似文献
6.
W.C. Seabergh 《Ocean Engineering》2010,37(1):48-58
A 1:50 scale physical model was constructed for the 17th Street Canal region, New Orleans, on the southern coast of Lake Pontchartrain, as part of the Interagency Performance Evaluation Task Force (IPET) study of Hurricane Katrina. The purpose of the 1350 m2 physical model that represented about 3.4 km2 of the local area was to aid in defining wave and water velocity conditions in the 17th Street Canal during the time period leading up to the breaching of the floodwall within the Canal. In the immediate period following this disaster, there were many hypothesis of failure put forth in the media. Some of these hypothesis indicated wave action may have been the underlying cause of the failure of the 17th Street Canal floodwall. Some performed numerical work with inappropriate boundary conditions, which indicated strong wave-generated currents may have caused erosion along the floodwalls. This physical model study indicated a number of wave-attenuating processes occurring as waves approached the location of the breach. Wave height reduction resulted due to: (1) refraction of wave energy over the shallower submerged land areas surrounding the harbor away from the canal; (2) reflection of energy off vertical walls in the region between the entrance to the canal near the Coast Guard Harbor and the bridge; and (3) interaction of the wave with the Hammond Highway bridge, including reflection and transmission loss. Wave heights near the lakeside of the bridge were 0.3-0.9 m in height, reduced from 1.8 to 2.7 m wave heights in the open lake. Waves on the south side of the bridge, near the breach, were further reduced to heights below 0.3 m. These results supported the conclusion that waves were not a significant factor for the 17th Street Canal floodwall failure. Other IPET investigations determined floodwall failure was of a geotechnical nature due to the high surge water level. The physical model also provided calibration information for numerical wave models. The effects of debris on flow and waves after the breach was formed were also investigated. 相似文献
7.
大型底栖动物是河流生态系统中重要的生态类群,研究其群落组成及分布特征能为河流生态系统管理提供理论支撑。2018年6月(夏季)和11月(秋季),在崇明岛内河设置16个固定站点,开展了拖网和地笼相结合的大型底栖动物调查,分析研究了崇明岛内河大型底栖动物群落的组成与分布特征及影响因子。调查期间共采集到大型底栖动物14种,分属5目8科,主要为节肢动物。其中,淡水型10种,河口半咸水型3种,降海洄游型1种。从空间分布来看,北横引河记录12种,南横引河记录6种,竖河记录11种;不同河道大型底栖动物群落组成均以淡水型种类为主,主要优势物种为日本沼虾(Macrobrachium nipponense)和秀丽白虾(Exopalaemon modestus);北横引河大型底栖动物群落的物种数、多度及生物量均高于南横引河;而竖河介于两者之间。夏季大型底栖动物群落的物种数、多度和生物量均高于秋季,季节变化是崇明岛内河大型底栖动物群落组成变化的重要特征之一。综合来看,崇明岛内河大型底栖动物群落组成特征兼具内陆河流和河口区特点,它与崇明岛区位特征、河流水文及生境条件、水质特征及区域人类活动等多种因素有关。 相似文献
8.
Erkan Gökaşan Oya Algan Hüseyin Tur Engin Meriç Ahmet Türker Mehmet Şimşek 《Geo-Marine Letters》2005,25(6):370-377
A detailed stratigraphic investigation based on high-resolution seismic profiles revealed that the delta at the southern entrance
of the Istanbul Strait consists of three parasequence sets. The lowermost parasequence shows a sea-level stillstand at the
beginning of the lowstand systems tract, possibly at 11,000±1,100 a b.p., whereas the upper two parasequences reflect deposition
at lowstand and during the subsequent transgression. A maximum flooding surface may be developing on the delta at present.
The delta is located on the eastern side of the Istanbul Strait canyon, with east–west prograding parasequences. The development
of the delta is clearly associated with the Kurbağalı Stream on the east coast, and not with the Black Sea outflow through
the strait. The geometry of the delta indicates a radial architecture arranged from northeast to southwest. 相似文献
9.
Scales of recruitment variability in warming waters: Comparing native and introduced oysters in Hood Canal,Washington, USA 
下载免费PDF全文
下载免费PDF全文 The effect of climate change on natural oyster recruitment has the potential to disrupt many of the ecosystem services oysters provide. Due to the temperature‐sensitivity of reproduction, oyster recruitment may shift as water temperatures rise. A biological imprint of climate change was revealed in a multi‐decadal time series of recruitment of non‐native Pacific oysters (Crassostrea gigas) in the main stem of Hood Canal, Washington, USA, extracted from historic fishery documents. Water in July and August warmed significantly from 1945 to 1995 (0.028 ± 0.004°C per year [±SE]) and accounted for an increase in Pacific oyster recruitment (7% per year, 0.028 ± 0.006 spat per year on log scale [±SE]); recruitment also strongly tracked inter‐annual variability in summer water temperature. Methods used to collect historical data were repeated in 2013–2015 when recruitment of both Pacific oysters and native Olympia oysters (Ostrea lurida) were recorded in main stem and lower Hood Canal. Both historic and modern data show large variation within and between years for temperature as well as recruitment. The modern data add information regarding spatial variation, in that recruitment patterns in the two regions of Hood Canal were decoupled. As temperatures continue to increase, non‐native Pacific oysters are likely to be favored over Olympia oysters, which recruit earlier at lower temperatures and presently contribute less than half of total oyster recruits. Future recruitment, however, may be limited by environmental factors other than temperature, a point indicated particularly in Hood Canal where many subtidal species already respond strongly to gradients in dissolved oxygen. 相似文献
10.
京杭运河续建工程韩庄枢纽船闸基坑开挖施工 总被引：1，自引：0，他引：1
韩庄船闸是京杭运河续建工程建设中重要工程,本文对船闸基坑大开挖施工以及施工过程中出现的问题和采取的处理措施进行了总结。 相似文献
11.
The historical Golden Horn Estuary (GHE), near the confluence of the Istanbul Strait (Bosphorus) and the Sea of Marmara in
the European part of Istanbul, has been used as a natural harbor since 330 a.d. The sedimentary infill of the GHE is 15–46 m thick, deposited unconformably above the turbiditic sandstones of the Carboniferous
Trakya Formation. Chronostratigraphic and paleontological analyses of the infill sequence indicate that the GHE was a fluvial
channel prior to 13,500 cal. a (calibrated to calendar years) B.P. It subsequently became gradually influenced by marine waters,
and was a brackish-water environment until 9,500 cal. a B.P. Normal marine salinities prevailed at ca. 9,500−5,600 cal. a
B.P., with suboxic/dysoxic bottom-water conditions. The increase in salinity at 9,500 cal. a B.P. was most likely caused by
Mediterranean water outflow into the Black Sea through the Istanbul Strait. The estuary was influenced by large fluvial inputs
between 5,600 and 1,000 cal. a B.P., possibly during a distinct pluvial period, as shown by coarse siliciclastic sediments
deposited on the flanks. It has become a highly polluted environment with marked anthropogenic inputs during the last millennium.
The finding that the sediment infill sequence above the Carboniferous basement is not older than about 20 ka strongly suggests
that the Golden Horn Estuary acquired its present-day morphology during the late glacial–Holocene period. 相似文献
12.
In previous papers we have looked at open registries, the Panama maritime sector and Panama Canal operations and management. No maritime study of Panama is complete, however, without a detailed look at the Panama Canal's main port system, which has enjoyed remarkable growth since the privatization of the terminal ports of Cristóbal and Balboa in 1995. This paper looks at the evolution and development of the Canal's port system; its stewardship, initially by the American authorities governing the Canal and, post-transition, by the Panamanians, and includes a study of the driving forces that led to privatization. We will conclude by looking at the results of the successful reform of the system, currently considered a primary model for other Latin American countries. 相似文献
13.
利用二维水动力数学模型模拟胶莱人工河道潮流运动,并分析了胶州湾湾口设置潜堤前后胶莱人工河道水质点的运动轨迹和水位变化过程。结果表明,开通胶莱人工河道能够使黄海的胶东湾海水向渤海的莱州湾输运,但不设置潜堤时从胶州湾到莱州湾的海水输运平均流速较小;设置潜堤后胶州湾水位高于莱州湾水位的时间变长,从黄海到渤海之间的水体输运能够得到加速。计算结果还表明,潜堤顶部与平均水面距离较小时,黄、渤海之间水体输运较快。 相似文献
14.
针对目前京驼河续建工程港口建设的实际情况,分析了影响京杭运河续建工程港口建设的主要问题是投资制品大,原设计规模偏大,港口运量设计船型和装卸机械偏大,并提出了修正港口初步设计和由航运部门兴建逐渐转为乡镇兴建的建议。 相似文献
15.
Many numerical analyses of New Orleans levee and floodwall sections adopted mostly isotropic soil models partly due to the inherent simplicity of isotropic models. However, the isotropic models may not be sufficient to properly address the anisotropic behavior of soils. To overcome this imperfection, this study incorporated an anisotropic Modified Cam Clay model in a commercially available finite difference code, FLAC3D, and analyzed a floodwall and levee section in the 17th St. Canal in New Orleans. The analysis showed that the anisotropic model resulted in a similar overall deformation to the Mohr-Coulomb isotropic model. However, the anisotropic model showed more widely spread yielded elements and higher shear strain gradient in the Lacustrine clay layer, reconfirming that the Lacustrine clay layer played a major role for the failure in the 17th St. Canal. This result also signified that the isotropic Mohr-Coulomb model might be good for evaluating overall behavior in moderate deformation problems, while the anisotropic Modified Cam Clay model was good even for large strain problems where more accurate evaluation of yielding is needed. 相似文献
16.
17.
荆马河是造成京杭运河徐州段污染的主要纳污、排污河流，河中沉积物约三万吨，沉积深度在０．４米至１．８米之间。本文论述了用柴露草微核技术对沉积物致突变性的研究方法和结果，探讨了对沉积的处理方式。 相似文献
18.
Abstract. The authors demonstrate the probable immigration and stable settling of the pycnogonid Ammothea hilgendorfi (B öhm , 1879) at one station in the lagoon of Venice. The species is widely distributed naturally on both sides of the Pacific Ocean and has probably immigrated on ship hulls through the Suez Canal to the Mediterranean. Two more cases (the pycnogonid Anoplodactylus portus and the amphipod Elasmopus pectenicrus ) of adventitious species in this sea are compared. 相似文献
19.
Mechanics of Sediment Transport. Edited by B. Mutlu Sumer and A. Muller. Proceedings of Euromech 156, Istanbul, 12–14 July 1982. Rotterdam: A. A. Balkema, 1983. 285 pp. $45.00. Gear Drive Systems: Design and Application, Peter Lynwander, New York and Basel: Marcel Dekker, Inc., 1983. Price: $49.50. 相似文献
20.
Stephanie K. Moore Nathan J. Mantua Jan A. Newton Mitsuhiro Kawase Mark J. Warner Jonathan P. Kellogg 《Estuarine, Coastal and Shelf Science》2008,80(4):545-554
Temporal and spatial patterns of variability in Puget Sound's oceanographic properties are determined using continuous vertical profile data from two long-term monitoring programs; monthly observations at 16 stations from 1993 to 2002, and biannual observations at 40 stations from 1998 to 2003. Climatological monthly means of temperature, salinity, and density reveal strong seasonal patterns. Water temperatures are generally warmest (coolest) in September (February), with stations in shallow finger inlets away from mixing zones displaying the largest temperature ranges. Salinities and densities are strongly influenced by freshwater inflows from major rivers during winter and spring from precipitation and snowmelt, respectively, and variations are greatest in the surface waters and at stations closest to river mouths. Vertical density gradients are primarily determined by salinity variations in the surface layer, with stations closest to river mouths most frequently displaying the largest buoyancy frequencies at depths of approximately 4–6 m. Strong tidal stirring and reflux over sills at the entrance to Puget Sound generally removes vertical stratification. Mean summer and winter values of oceanographic properties reveal patterns of spatial connectivity in Puget Sound's three main basins; Whidbey Basin, Hood Canal, and Main Basin. Surface waters that are warmed in the summer are vertically mixed over the sill at Admiralty Inlet and advected at depth into Whidbey Basin and Hood Canal. Cooler and fresher surface waters cap these warmer waters during winter, producing temperature inversions. 相似文献