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881.
882.
883.
An improved methodology for assessing risk in aircraft operations at airports, applied to runway overruns 总被引:1,自引:0,他引:1
The paper addresses the need for models to assess risk at any particular airport, based on risk management principles used by the present risk management process, that use all available data on previous accidents. The case of runway overruns is taken as an example application, because new regulations require the provision of much longer Runway End Safety Areas than had previously been the norm. The paper presents models for overruns arising from both landings and aborted takeoffs. In each case models of overrun risk, of wreckage location and of the consequences are detailed. An example application of the models is then given in a hypothetical risk assessment.The models, though adding value to existing methods of assessing risk, are not as good as they could be, due to the lack of data on normal operations. It was therefore possible only to relate the rate of overruns to the rate of occurrence of the possible driving factors for a few factors where such comparable data on normal operations existed. It is recommended that effort be put into the collection of data to allow a more comprehensive analysis. 相似文献
884.
While there has been sustained debate on the issue of provincial and state versus local government environmental planning, maintaining privately owned natural resources in the public interest is increasingly viewed as beyond the scope of local governments alone. This paper describes and compares province- and state-level mandates and options for local governments (i.e., city, county, or district) to regulate land uses of environmentally sensitive areas (ESAs) in British Columbia in Canada and in Washington and Oregon in the United States. We define ESAs as landscape elements or places that are vital to the long-term maintenance of biological diversity, soil, water, and other natural resources, especially as they relate to human health, safety, and welfare, both on-site and in a regional context. Underlying similarities are that all three jurisdictions legally express the need for land-use planning by local governments in managing ESAs. Although all three jurisdictions exhibit similar problems in their attempt to accomplish this, ESA planning by local governments is an optional process in British Columbia and Washington but mandatory in Oregon. Furthermore, actual processes prescribed by each of the three jurisdictions are quite different. The information base upon which local regulation of privately held ESAs depends is variable, both within and between the province- and statelevel jurisdictions. Other than for some specific water-related resources, standard definitions and inventory methods for ESAs are lacking, as is coordination among local governments or among the province- and state-level governments. This study concludes that there is a need for a regional environmental information system in the Pacific Northwest based upon an integrated and scientific approach toward ESA structures and functions. 相似文献
885.
Frederick Steiner Scott Pieart Edward Cook Jacqueline Rich Virginia Coltman 《Environmental management》1994,18(2):183-201
The protection of wetlands and riparian areas has emerged as an important environmental planning issue. In the United States,
several federal and state laws have been enacted to protect wetlands and riparian areas. Specifically, the federal Clean Water
Act includes protection requirements in Sections 301 and 303 for state water quality standards, Section 401 for state certification
of federal actions (projects, permits, and licenses), and Section 404 for dredge and fill permits. The Section 401 water quality
state certification element has been called the “sleeping giant” of wetlands protection because it empowers state officials
to veto or condition federally permitted or licensed activities that do not comply with state water quality standards. State
officials have used this power infrequently. The purpose of this research was to analyze the effectiveness of state wetland
and riparian programs. Contacts were established with officials in each state and in the national and regional offices of
key federal agencies. Based on interviews and on a review of federal and state laws, state program effectiveness was analyzed.
From this analysis, several problems and opportunities facing state wetland protection efforts are presented. 相似文献
886.
本文从气候学角度统计、分析了台风登陆或影响我国30°N以南地区8省(浙江、福建、广东、广西、海南、台湾、江西、湖南)而产生风灾的频数分布、季节变化、年变化以及概率分布的特征。 相似文献
887.
Management and valuation of an environmentally sensitive area: Norfolk Broadland,England, case study 总被引:1,自引:0,他引:1
Wetlands, like any other environmentally sensitive resource, require very careful evaluation. While it is accepted that all wetlands may be equally valuable in terms of maintaining global life-support systems, individual areas may be ranked according to their uniqueness or the irreplaceability of the resource should the wetland be developed. The various techniques available for evaluating the wetland resource in the development versus conservation conflict situation are critically assessed. Indirect appraisal via the opportunity cost method can generate valuable data which have contributed to the mitigation of such conflict situations.The Broadland, in Norfolk, England, recently designated an environmentally sensitive area (ESA), provides a case study example of wetland management. The search for an acceptable flood alleviation strategy for the ESA is examined in detail. The economic and environmental asset structure of the study area is examined at two levels. A basic screening system is applied to each of the identified flood protection planning units to enable the rank ordering of the units. A more detailed appraisal is then made of the value of selected units so that the cost-effectiveness of any planned expenditure on flood protection works can be assessed. Specific management issues and their likely effect on the environment, in terms of land use for example, are also addressed. The 1986 Agriculture Act marks a potential watershed in British conservation policy. The ESA policy encompasses a dual management strategy that attempts to stimulate compatible agricultural and conservation practices and activities. Other countries that still retain significant unspoiled wetland resources may find that preemptive regulatory government intervention in favor of conservation would help to avoid the worst aspects of the British experience. 相似文献
888.
山东省地下水位下降引发的灾害及减灾对策 总被引:1,自引:0,他引:1
近二十年来山东省经济迅速发展与水资源匮乏的矛盾不断加剧。超量开采地下水导致地下水位持续的急剧下降,其结果引发了地裂缝、地面塌陷、海(咸)水入侵、生态环境恶化等一系列人为自然灾害。本文分析了这些灾害的基本特征并指出解决水资源不足是促进山东省经济持续高速发展并减轻地下水位下降灾害的根本措施。 相似文献
889.
农村生态环境破坏机理初探 总被引:1,自引:0,他引:1
农村生态环境的破坏已成为制约我国农村经济健康发展的因素之一。在概述我国农村生态环境主要问题的基础上,着重分析了导致生态环境恶化的原因,主要包括工业污染、农业污染、政府行为、城市化建设、农民的环境意识淡薄、环保基础设施薄弱等,并提出了相应的对策。 相似文献
890.
基于多种预测模型的玉米低温冷害预测集成模型 总被引:2,自引:0,他引:2
引入大气环流特征量因子、500hPa高度场因子、太平洋海温因子以及预报量本身的均值周期因子等四类因子的低温冷害预测子模型来建立玉米低温冷害预测集成模型。利用该集成模型预报下一年温度等级时,将上一年的实况资料输入预测模型,滚动预测,克服了统计模型预报时效短的缺点,且试报准确性高,无错报。 相似文献