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71.
Philip M. Fearnside 《Environmental management》1989,13(4):401-423
The Balbina Dam in Brazil's state of Amazonas floods 2360 km2 of tropical forest to generate an average of only 112.2 MW of electricity. The flat topography and small size of the drainage basin make output small. Vegetation has been left to decompose in the reservoir, resulting in acidic, anoxic water that will corrode the turbines. The shallow reservoir contains 1500 islands and innumerable stagnant bays where the water's residence time will be even longer than the average time of over one year. Balbina was built to supply electricity to Manaus, a city that has grown so much while the dam was under construction that other alternatives are already needed. Government subsidies explain the explosive growth, including Brazil's unified tariff for electricity. Alternative power sources for Manaus include transmission from more distant dams or from recently discovered oil and natural gas deposits. Among Balbina's impacts are loss of potential use of the forest and displacement of about one third of the surviving members of a much-persecuted Amerindian tribe: the Waimiri-Atroari. The dam was closed on 1 October 1987 and the first of five generators began operation in February 1989. The example of Balbina points to important ways that the decision-making process could be improved in Brazil and in the international funding agencies that have directly and indirectly contributed to the project. Environmental impact analyses must be completed prior to decisions on overall project implementation and must be free of influence from project proponents. The current environmental impact assessment system in Brazil, as in many other countries, has an undesirable influence on science policy, in addition to failing to address the underlying causes of environmentally destructive development processes and inability to halt irreversible projects like Balbina. 相似文献
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73.
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
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75.
This paper examines the recent appearance of four migratory species in the Upper Mekong: Dasyatis laosensis, Anguilla bicolor, Anguilla marmorata, and Chitala ornata. Since 2006 these species have been continually sampled in an area below Jinghong Dam in Xishuangbanna, China. This region is far beyond their historical upstream distribution, and the reasons for these appearances and their subsequent impact on river ecosystem are considered. 相似文献
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