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51.
1991/1992年是厄尔尼诺年,也是全球自然灾害频发、重灾事件突出的异常年份。本文对发生在1991/1992年厄尔尼诺事件期间的全球主要气象灾害进行简介和评述。 相似文献
52.
Analysis of Sediment Retention in Western Riverine Wetlands: The Yampa River Watershed,Colorado, USA
We quantified annual sediment deposition, bank erosion, and sediment budgets in nine riverine wetlands that represented a watershed continuum for 1 year in the unregulated Yampa River drainage basin in Colorado. One site was studied for 2 years to compare responses to peak flow variability. Annual mean sediment deposition ranged from 0.01 kg/m2 along a first-order subalpine stream to 21.8 kg/m2 at a sixth-order alluvial forest. Annual mean riverbank erosion ranged from 3 kg/m-of-bank at the first-order site to 1000 kg/m at the 6th-order site. Total sediment budgets were nearly balanced at six sites, while net export from bank erosion occurred at three sites. Both total sediment deposition (R2 = 0.86, p < 0.01) and bank erosion (R2 = 0.77, p < 0.01) were strongly related to bankfull height, and channel sinuosity and valley confinement helped to explain additional variability among sites. The texture and organic fraction of eroded and deposited sediment were relatively similar in most sites and varied among sites by watershed position. Our results indicate that bank erosion generally balances sediment deposition in riverine wetlands, and we found no distinct zones of sediment retention versus export on a watershed continuum. Zones of apparent disequilibrium can occur in unregulated rivers due to factors such as incised channels, beaver activity, and cattle grazing. A primary function of many western riverine wetlands is sediment exchange, not retention, which may operate by transforming materials and compounds in temporary sediment pools on floodplains. These results are considered in the context of the Hydrogeomorphic approach being implemented by the U.S. government for wetland resource management. 相似文献
53.
三峡水库自 2 0 0 3年蓄水后 ,水对斜坡 (滑坡 )的软化作用和库岸再造大大改变了库区的工程地质条件 ,库区的地质灾害严重制约了库区移民迁镇工程 ,场地建筑安全评价显得尤为重要。笔者根据库区工程地质的特点 ,提出了场地建筑适宜性评价的指标体系 ,建立了场地建筑安全评价人工神经网络模型。通过对红石包滑坡进行各种工况下的稳定性评价 ,利用稳态坡形、坡角工程地质类比法对红石包进行库岸再造的预测 ,对三峡库区巴东县新城区红石包油库建筑进行安全评价。为库区移民迁镇工作提供科学依据。 相似文献
54.
In this paper we examine the reconstitution of the Emergency Operations Centre (EOC) after its destruction in the World Trade Center attack, using that event to highlight several features of resilience. The paper summarises basic EOC functions, and then presents conceptions of resilience as understood from several disciplinary perspectives, noting that work in these fields has sought to understand how a natural or social system that experiences disturbance sustains its functional processes. We observe that, although the physical EOC facility was destroyed, the organisation that had been established to manage crises in New York City continued, enabling a response that drew on the resources of New York City and neighbouring communities, states and the federal government. Availability of resources--which substituted for redundancy of personnel, equipment and space--pre-existing relationships that eased communication challenges as the emergency developed and the continuation of organisational patterns of response integration and role assignments were among the factors that contributed to resilience following the attack. 相似文献
55.
Jason Bradbury Phillip Cullen Grant Dixon Michael Pemberton 《Environmental management》1995,19(2):259-272
The wash from high-speed tourist cruise launches causes erosion of the formerly stable banks of the lower Gordon River within
the Tasmanian Wilderness World Heritage Area. Speed and access restrictions on the operation of commercial cruise vessels
have considerably slowed, but not halted erosion, which continues on the now destabilized banks. To assess the effectiveness
of restrictions, bank erosion and natural revegetation are monitored at 48 sites using erosion pins, survey transects, and
vegetation quadrats. The subjectively chosen sites are grouped on the basis of geomorphology and bank materials. The mean
measured rate of erosion of estuarine banks slowed from 210 to 19 mm/year with the introduction of a 9 knot speed limit. In
areas where cruise vessels continue to operate, alluvial banks were eroded at a mean rate of 11 mm/yr during the three-year
period of the current management regime. Very similar alluvial banks no longer subject to commercial cruise boat traffic eroded
at the slower mean rate of 3 mm/yr. Sandy levee banks have retreated an estimated maximum 10 m during the last 10–15 years.
The mean rate of bank retreat slowed from 112 to 13 mm/yr with the exclusion of cruise vessels from the leveed section of
the river. Revegetation of the eroded banks is proceeding slowly; however, since the major bank colonizers are very slow growing
tree species, it is likely to be decades until revegetation can contribute substantially to bank stability. 相似文献
56.
David Higdon 《Journal of Environmental Planning and Management》1986,29(2):91-95
The author contributed to a short ‘in service’ course for staff engaged on a World Bank upgrading project for Ethiopian housing. The project includes both the building of new houses by self‐build co‐operatives on the periphery of Addis Ababa, and the upgrading of a dense inner city area in conditions of acute deprivation. The paper is a highly personal account of the author's impressions of the value of such initiatives. 相似文献
57.
We evaluated the conservation attitudes of the local villagers living adjacent to the Kalakad-Mundanthurai Tiger Reserve in southern India 6 years after implementation of a World Bank funded eco-development project. We assessed attitudes towards three facets of conservation: the tiger, an emblematic species signifying India's commitment to wildlife conservation; the forest, a principle source of fuel-wood and other products; and the Forest Department, which manages the forest. More specifically we predicted that (i) attitudes would be an effective predictor of resource use interest in the forest and (ii) benefits obtained from the EDP would create more favorable attitudes towards conservation and the protected area employees. Twelve villages located within 3 km from the reserve boundary were chosen and 2-3% of the households interviewed with regard to their attitudes towards these three facets of conservation, their household resource use patterns, wealth, sex, age and length of residency. We found significant associations between wealth, sex, age and both tiger and forest conservation. Providing benefits has not changed the underlying attitudes of the communities. The poorer sections of society, whether receiving benefits or not, tended to support tiger conservation because conserving wildlife did not affect their livelihood in any way, whereas both the rich and poor had misgivings about forest conservation due to dependency on forest products. We conclude that the eco-development project has not effectively addressed the most important of the local concerns. 相似文献
58.
Non-structural streambank stabilization, or bioengineering, is a common stream restoration practice used to slow streambank
erosion, but its ecological effects have rarely been assessed. We surveyed bank habitat and sampled bank macroinvertebrates
at four bioengineered sites, an unrestored site, and a comparatively less-impacted reference site in the urban Peachtree-Nancy
Creek catchment in Atlanta, GA, USA. The amount of organic bank habitat (wood and roots) was much higher at the reference
site and three of the bioengineered sites than at the unrestored site or the other bioengineered site, where a very different
bioengineering technique was used (“joint planting”). At all sites, we saw a high abundance of pollution-tolerant taxa, especially
chironomids and oligochaetes, and a low richness and diversity of the bank macroinvertebrate community. Total biomass, insect
biomass, and non-chironomid insect biomass were highest at the reference site and two of the bioengineered sites (p < 0.05). Higher biomass and abundance were found on organic habitats (wood and roots) versus inorganic habitats (mud, sand,
and rock) across all sites. Percent organic bank habitat at each site proved to be strongly positively correlated with many
factors, including taxon richness, total biomass, and shredder biomass. These results suggest that bioengineered bank stabilization
can have positive effects on bank habitat and macroinvertebrate communities in urban streams, but it cannot completely mitigate
the impacts of urbanization. 相似文献
59.
This study aimed to make a review and forecast on fertilizers consumption worldwide in order to provide basal data for the
decision-making of fertilizers production and for the environmental impact assessment of fertilizers application. It was found
that fertilizers consumption was dependent on human population and the increase of fertilizers consumption was mainly resulted
from expansion of human population. The univariate linear model, y=a+rx(t), where y is the fertilizers consumption, x(t) is the total human population at year t, r is the annual fertilizers consumption per capita, was used to fit historical data of fertilizers consumption, and the forecasts
during 2010 to 2030 were given in detail. Model analysis showed that world’s per capita annual consumption of total fertilizers,
nitrogenous fertilizers, phosphate fertilizers, and potash fertilizers, were 34.6, 24.4, 6.6, and 3.7 kg, respectively. Per
capita annual consumption of total fertilizers for Asia, Africa, Caribbean, Oceania, North & Central America, Europe, and
South America were 38.8, 5.9, 6.8, 114.0, 62.9, −0.9, and 43.6 kg, respectively. Compared to the current level, the world’s
total fertilizers consumption would reach 226,150,381 Mt by 2030, an increase of 32.1% against current level. Worldwide consumption
of nitrogenous fertilizers, phosphate fertilizers, and potash fertilizers would reach 141,800,601, 50,961,129, and 33,388,650 Mt
by 2030, increasing 37.5, 25.8, and 21.2% based on current levels. Consumption of total, nitrogenous, phosphate, and potash
fertilizers in Asia and Africa would increase 54 to 55% and 40 to 60% by 2030, respectively. Total fertilizers consumption
in North & Central America would see an increase of 39.4% by 2030, and in South America and Oceania it would increase by 30.9
and 64.7%, respectively. By 2030, Caribbean’s consumption for total fertilizers would increase 2.8%. Europe’s total fertilizers
consumption was forecast to continuously decline and would have a decrease of 2.4% by 2030. Annual relative growths of consumption
of total fertilizers, nitrogenous fertilizers, phosphate fertilizers, and potash fertilizers for the world, Africa, Asia,
and South America were forecast to decrease in the forecast period. For North & Central America, annual relative growths of
consumption of total fertilizers and nitrogenous fertilizers would decrease and the others would increase annually by 2030.
Annual relative growths of consumption of total fertilizers, phosphate fertilizers, and potash fertilizers for Oceania were
forecast to rise annually by 2030. Europe’s annual relative growths of consumption of total fertilizers and potash fertilizers
would decrease in the future. 相似文献
60.
Wenjun Z 《Environmental monitoring and assessment》2007,125(1-3):301-312
Our world is largely dependent upon the forestry productions. Through the exploitation of forest reserves, we manufacture
various industrial products, furniture, and obtain fuel and energy. Forestry productions should be conducted without large-scale
deforestation and environmental degradation. In present study we perform a review and forecast analysis on forestry productions
worldwide, with the objectives of providing an insight into the trend for several types of forestry productions in the future,
and providing referential data for sustainable forestry productions and environmental management. Polynomial functions are
used to fit trajectories of forestry productions since 1961 and forecasts during the coming 20 years are given in detail.
If the past pattern continues, world fibreboard production would dramatically grow and reach 224,300,000 ± 44,400,000 m3 by the year 2020, an increase up to 240.7 to 408.9% as compared to the present level. Roundwood production of the world would
change by −55.5 to 70.4% and reach 3,526,600,000 ± 2,066,800,000 m3 by 2020. In 2020 world production of sawlogs and veneer logs would change by −100 to 164.6% and reach 1,212,900,000 ± 1,242,600,000 m3. Global wood fuel production would change by −68.9 to 1.4% and reach 1,130,900,000 ± 600,800,000 m3 by 2020. Forestry productions in developed countries would largely surpass productions in developing countries in the near
future. World forestry production grew since 1961 excluding wood fuel. Roundwood and wood fuel account for the critical proportions
in the forestry productions. Wood fuel production has being declined and rapid growing of roundwood production has slowed
in recent years. Widespread use of regenerative wood substitutes and worldwide afforestation against deforestation will be
among the most effective ways to reduce deforestation and environment degradation associated with forestry productions. 相似文献