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71.
72.
为了保证岗南水库大坝的安全运营 ,采用Fellenius圆弧法对整个岗南水库大坝断面的安全稳定性进行了分析 ,确定了不满足稳定性要求的断面的最小稳定安全系数及其最危险滑弧位置 ,并对其可能的原因进行了分析评价 ,给出了结论和建议 相似文献
73.
Stephen M. Born Kenneth D. Genskow Timothy L. Filbert Nuria Hernandez-Mora Matthew L. Keefer Kimberly A. White 《Environmental management》1998,22(3):359-370
/ There are tens of thousands of small dams in the United States; many of these aging structures are deteriorating. Governments and dam owners face decisions regarding repair or removal of these structures. Along with the many benefits society derives from dams and their impoundments, numerous recent ecological studies are revealing the extensive alteration and degradation of river ecosystems by dams. Dam removal-a principal restoration strategy-is an infrequent event. The major reasons for removal have been public safety and the high costs associated with repair; the goal of river ecosystem restoration now warrants greater attention. Substantial study is being given to the environmental aspects of dams and dam removals, but very little attention has been given to the socioeconomic and institutional dimensions associated with the removal of dams, although these factors play a significant role in the removal decision-making process. Based on a case study of dam removals in Wisconsin-where more than 30 of the state's 3600 small dams have been removed in the past few decades-legal, financial, and socioeconomic issues associated with dam removal are documented and assessed. Dam removal has been complex and contentious, with limited community-based support for removal and loss of the impounded waters. In cases examined here, the estimated costs of repairing a dam averaged more than three times the cost of removal. The availability of governmental financing has been a key determinant in removal decisions. Watershed-scale ecological considerations are not major factors for most local interests. As watershed management and restoration increasingly include dam removal options as part of an integrated strategy, more attention will need to be focused on socioeconomic factors and stakeholder perspectives-variables that strongly influence the viability of this management alternative.KEY WORDS: Dam removal; River restoration; Institutions; Stakeholders 相似文献
74.
Nature reserves have developed rapidly over the decades in China and play a significant role in the function of ecosystem services. The function of ecosystem services in nature reserves, however, has tended to decline in recent years due to natural hazards and human activities. Based on land use, the variation of ecosystem services value (ESV) during 2000–2010 in national nature reserves in Sichuan was evaluated. We analyzed the comprehensive effects of natural disasters and human activities on the decline of ESVs. Total ESV in the national nature reserves in Sichuan was approximately 2741.35 million US$ in 2000, 2616.81 million US$ in 2005, and 2499.06 million US$ in 2010, representing a decrease of 242.29 million US$, or 8.84%, in the decade. Forestland, grassland, wetland, and water bodies played vital roles in the function of ecosystem services, with an aggregated ESV of 99% of the total. The largest proportion of the total ESV was the protection of biodiversity at 48.6%. ESV of all land use types and single ecosystem services continued to decline during 2000–2010. A mechanism of adaptable risk prevention should be established, and unreasonable human activities should be avoided to protect ecosystems and to improve the functions of ecosystem services. 相似文献
75.
76.
Impulsive waves caused by subaerial landslides 总被引:10,自引:0,他引:10
This paper presents the experimental results of impulsive waves caused by subaerial landslides. A wide range of effective
parameters are considered and studied by performing 120 laboratory tests. Considered slide masses are both rigid and deformable.
The effects of bed slope angle, water depth, slide impact velocity, geometry, shape and deformation on impulse wave characteristics
have been inspected. The impulse wave features such as amplitude, period and also energy conversation are studied. The effects
of slide Froude number and deformation on energy conversation from slide into wave are also investigated. Based on laboratory
measured data an empirical equation for impulse wave amplitude and period have been presented and successfully verified using
available data of previous laboratory works. 相似文献