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本文分析水利工程对生态系统胁迫的分析,主要是水利工程对河流生态系统的胁迫的原因分析。本文主要分析河流生态系统的特征以及其价值,然后分析水利工程对于河流生态系统的胁迫,最后简要分析水利工程对于生态系统胁迫的原因。 相似文献
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通过分析人类经济与河流作用的历史过程,探求符合“人与自然和谐相处”的河流生态系统与人类经济发展的模式,使得人与河流之间的相互作用沿着这种变化趋势发展,促进人类与自然之间关系的进—步协调,保障经济社会的可持续发展。 相似文献
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以往人们在城市河道整治过程中只考虑到工程结构的安全性及耐久性,故多采用砌石、混凝土等材料修筑硬质护岸,隔断了水生生态系统和陆地生态系统之间的联系,导致河流失去原本完整的结构和作为城市生态廊道的功能,进而影响到整个城市生态系统的稳定。因此,做好城市河流的生态修复工作对于生态城市的建设具有十分重要的意义。 相似文献
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一位科学家以一份迟到20年的环评报告,为一条内陆江河的"消失"立此存照。作为一条江,"九龙江"事实上已经消失了。它被称为闽南地区的母亲河,流经龙岩、漳州、厦门三市。更严谨的说法应该是:九龙江流域已经被切割成数百个不连续的、非自然的河段,造成生态破碎,河流生态已完全改变。横锁它的是遍布整个流域的超过1000座的水电站,没 相似文献
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山区通航河流中桥梁选址和设计应注意的问题及通航影响评价 总被引:2,自引:0,他引:2
文章就山区通航河流的基本特征、河道特性,阐述了桥梁在选址和设计时应注意的一些基本问题,并在建桥对河道通航影响作出评价的基础上,简述了保障桥区通航安全的相应措施和手段。 相似文献
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河道二维数值模拟糙率横向分布研究 总被引:2,自引:0,他引:2
糙率是河道对水流阻力大小的描述。文中系统地总结了推求糙率的各种常用方法,分析了糙率沿河道横断面分布的非统一性。采用横断面各个垂线能坡相同的假定原理,利用谢才—曼宁公式,推导出了断面糙率再分配函数。通过点绘多条河流不同河型的不同断面形态的实测水文资料,建立了可应用于平面二维水流数值模拟中阻力沿河宽分布的经验公式,将得到的断面糙率再分配函数应用到对应的河段的平面二维流场数值计算中,计算结果与实测结果吻合良好,解决了计算流速与天然实测流速断面分布不一致的问题,提高了水流二维数值模拟的精度。 相似文献
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S. G. Hosking 《Coastal management》2013,41(1):35-46
Estuaries are last in line as a recipient of river water and for this reason they are particularly vulnerable to negative environmental impacts due to water scarcity and pollution. They only receive the runoff that has not been abstracted or prevented from reaching rivers. When this runoff is substantially reduced their functionality is undermined and they often become less attractive for recreational use. This article explores some aspects entailed in efficiently managing the allocation of water to estuaries problem and some associated problems. It is shown that efficient management requires the marginal social costs of the inflows to be brought into equivalence with the marginal social values of the inflows, and these values may be estimated, but that there are the challenges in this estimation and in linking these estimates to the welfare of the people in whom the managers of river systems are (presumed to be) interested. 相似文献
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Lu Guangbin 《中国水运》2006,(2)
我国河流众多,可开发的航运资源丰富,但在各类交通运输系统日益发达的今天,我国内河航运却陷入了停滞不前的困境。如何认清我国内河航运的现状,结合绿色航运的理念来开发航运资源,实现内河航运的可持续发展,是本文探讨的主要内容。 相似文献
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The Black Sea northwestern shelf (NWS) ecosystem has been subjected to the strongest anthropogenic pressure of the entire Black Sea as about 80% of the freshwater runoff is discharged there.This paper presents a review of the global environmental changes related mainly to increased eutrophication in the western Black Sea basin.A case study (CoMSBlack 92a cruise) attempts to highlight the interaction of some natural and anthropogenic factors responsible for specific chemical and biological features in the western Black Sea environment. The significance of processes located near the Danube river mouth, which, due to their relatively small space scale, have not been recognized before, is clarified. Hydrological processess of specific importance to the distribution and transformation of antropogenic inputs are river plume dynamics, coastal upwelling and mixing and downwelling over the shelf break and slope in this part of the basin. A layer of low hydrological variability (“conservative layer”) appears to be a natural feature of the area, hypothesized to precondition specific biological and chemical processes there.The results suggest that the interplay between the Danube anthropogenic nutrient load with the natural hydrological fronts and gradients provides opportunities for enhanced biological activity thus contributing to the global environmental changes in the Black Sea NWS. 相似文献
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舵机是船舶的重要设备,其功用是根据驾驶人员的意图改变船舶航向或维持拟定航向,使船舶具有航行所必需的操纵性。在滩多流急、水情复杂的川江,舵机就像驾引人员的生命—样,是船舶安全的保障,其重要性不言而喻。但近来川江发生的几起舵机失灵事故,使得我们不得不从深层次分析其原因,采取有效的对策和应对措施,杜绝类似事故的发生。 相似文献