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81.
The siltation of reservoir causes many problems of management and environmental disturbances that are important to minimize. Solving these problems requires in particular a good knowledge of mud bank instabilities. In partnership with the Laboratoire National d'Hydraulique (LNH), a subsidiary of Electricite de France (E.D.F.), authors realize a study of soft soils sliding entailed by reservoir emptying. Using a geotechnical flat sliding mechanism, the theoretical formulation of the safety factor can be established when the sediment mass is submerged and emergent. The measurement campaign carried out makes it possible to obtain bathymetric and topographic surveys and a geotechnical characterization of the soil for the whole reservoir of Grangent dam, located on the Loire (France). The proposed model appears to agree satisfactorily with the instability of the zones emerged because of the emptying and with the stability of the profile after emptying. The use of this model within the framework of forecasts  相似文献   
82.
Since 1983, Ghana has been undergoing World Bank and International Monetary Fund (IMF) sponsored Structural Adjustment Programs (SAPs). The implementation of the SAPs, it is claimed, has arrested Ghana's economy from complete collapse, resulted in consistent growth in GDP averaging 6% over the past decade, reduced inflation levels, created budget surplus, and increased export earnings. Compared to the 1970s, these are the best of times indeed. But while these SAPs‐derived improvements in the national economy have been recorded at the macro level, the benefits at the micro level are a matter of considerable debate. This study revisits the issue of socioeconomic and spatial disparities that have characterized Ghana since colonial times, emphasizing the period from 1983 when Ghana's SAPs began. It examines current patterns of socioeconomic disparities with emphasis on the distribution of, and access to, health, education, basic services, and the like. The study focuses on urban‐rural as well as interregional disparities in the country.  相似文献   
83.
An oil spill fishery impact assessment model system has been applied to the Georges Bank-Gulf of Maine region to assess the sensitivity of probable impact on several key fisheries to spill location and timing. Simulations of the impact on the fishery of tanker spills (20 million gallons released over 5 days), at two separate locations for each season of the year, and blowout spills (68 million gallons released over 30 days) at one location, with monthly releases and at six other locations with seasonal spills have been studied. Atlantic cod has been employed as the principal fish species throughout the simulations. Impacts on Atlantic herring and haddock have also been investigated for selected cases. All spill sites are located on Georges Bank with the majority in the general region of OCS leasing activity.The results of these simulations suggest a complex interaction among spill location and timing, the spatial and temporal distribution of spawning, the population dynamics of the species under study, and the hydrodynamics of the area. For the species studied, spills occurring during the winter and spring have the largest impact with cod being the most heavily impacted followed by haddock and herring. In all cases, the maximum cumulative loss to the fishery of a one time spill event never exceeded 25% of the annual catch with the exact value depending on the number of ichthyoplankton impacted by the spill and the compensatory dynamics of the population.  相似文献   
84.
孙凡  于非  司广成  潘俊 《海洋科学》2019,43(1):15-27
在1982—2016年,苏北浅滩及长江口海域春季海表面温度主要呈现出从南至北、从近岸至离岸升温趋势逐渐减小的特征,其中长江口附近海域升温速率最大。研究显示,苏北浅滩及长江口附近海域春季海表面温度的长期升温趋势主要与该海域经向热输送及长江平流热输送的增强有关。进一步的研究发现,春季经向风速的增强导致该海域经向热输送的增加,而春季经向风速的年际及年代际变率又受到太平洋年代际振荡、北极涛动的调控,其中,太平洋年代际振荡指数与经向风速呈负相关,北极涛动指数与经向风速呈正相关,北极涛动指数的年际增加以及太平洋年代际振荡指数的年际降低使得春季南风增强,进而南向的冷平流减弱,北向的热平流增强,使该海域春季海表面温度长期升温。在此过程中,净热通量对其升温过程起到抑制作用,而前冬海温主要是对春季海表面温度的年代际振荡产生重要影响,其主要体现为1982—1999年的升温及2000—2016年的降温过程。  相似文献   
85.
颜万才 《江苏地质》1998,22(4):231-237
位于长江下游北岸某凹岸区的扬州港,因受局部塌岸的危害,多处建构物被毁,新落成的客运大楼产生不均匀沉降与裂缝,直接危及大楼的安全与使用,迫使该港长航客运中断。后在大楼西南侧岸边构筑了一道防护帷幕墙,并对大楼地基土进行了压密注浆加固,保住了大楼,控制了沉降,并使大楼处于稳定状态,恢复了长航客运。简述了该建筑物病害的成因,治理加固方案的设计与施工,效果验证等问题。  相似文献   
86.
广角地震测线(OBS973-2)位于南海南部陆缘,其地壳深部构造是研究南海共轭扩张及形成演化的直接证据之一.本文采用2D射线追踪技术,结合与之重合的多道地震测线(NH973-2)时深转换结果,对OBS973-2测线重新进行了正、反演研究,得到了礼乐滩及邻近海区的精细地壳结构.与前人结果相比,本文基于正反演速度模型,把测线分为陆壳区(0~200 km)、洋陆过渡区(200~280 km)和洋盆区(280~370 km).地壳结构在不同区域差异明显,陆壳区沉积层厚度横向差异大,且速度横向不均匀,地壳整体厚度大(约20 km),有横向速度差;洋陆过渡区速度和厚度横向均匀,地壳减薄(约8 km);洋壳区地壳厚度减薄至6 km.与以往研究相比,新的认识集中在两个方面,(1)在方法上,综合广角地震和多道地震数据,借助正演和反演方法,能够得到更多更可靠的地壳结构信息.(2)在地壳结构上,结合广角地震与多道地震,得到洋陆过渡区莫霍面向海减薄的形态及其埋深(约12~18 km,海平面为0 km);进一步验证礼乐滩区域在洋陆过渡区没有明显的高速层,为非火山型陆缘,其共轭扩张点为中沙地块;陆壳区上地壳强烈的拉张作用在速度模型表现出横向速度异常和低速区,在多道地震剖面上表现为大量10~20 km的正断层.  相似文献   
87.
The Asian Development Bank's (ADB) support for the development of the clean energy sector in Asia and the Pacific is examined, together with its implications for mitigating climate change. A key question is whether financing has shifted from fossil fuel projects to renewable energy and energy efficiency in the past decade (2000–2009). Financial data from the ADB – a multilateral source of significant financing in the region – are assessed, and 127 technology-deploying projects and 199 technical assistance projects are evaluated. The assessment suggests that clean energy assistance has gained momentum during the last few years, peaking in 2008, implying a considerable shift in energy investments from conventional fossil-fuel projects to clean energy. Although private sector involvement has been central to the ADB's investment policy, only 30% of funding has been channelled into this sector over the past decade. The reporting of clean energy investments has also progressed within the ADB by including renewable and energy efficiency components in conventional energy projects and other investments, which was not previously accounted for. Nevertheless, the ADB needs to address several challenges in the future, including sustaining funding for clean energy, strengthening private sector investments and improving financial reporting.  相似文献   
88.
1994-1997年的渔业统计显示:夏、秋汛渔获量高于冬、春汛.本文还探讨了1987-1998年中上层鱼类渔获量的变化与厄尔尼诺现象等的可能关系,提出了保护中上层鱼类资源的一些建议.  相似文献   
89.
1987年12月—1988年11月对闽南-台湾浅滩渔场上升流生态系进行了调查研究。研究结果表明,本研究海区的海水N/P比值的空间分布与水团的分布具有密切的关系。各水团的N/P比值不遵守Redfield常数15:1,并且在水团间存在一定的差别。在研究水团的分布及划分中,N/P比值可作一较好的参考值。闽浙沿岸水、次表层水和中深层水的N/P比值大于15;海峡南部混合水、海峡暖水、夏季近岸涌升水和浅滩南部涌升水的N/P比值小于15。前者主要是入海径流及有机体的充分分解所致,后者则为浮游植物对NO3-N和PO4-P的大量吸收及NO3-N和PO4-P再生速率上差异的结果。本文还讨论了水团的分布对营养盐和叶绿素分布的影响。  相似文献   
90.
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