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101.
Past on-site experience was linked to the crowding perceptions and use displacement of 383 on-site visitors to the peri-urban
Danube Floodplains National Park, Austria. Three visitor groups were determined according to their area experience: local
residents from Vienna and rural communities, having the highest level of experience; regional visitors from the city and eastern
Austria; and tourists from Austria and abroad with the lowest degree of experience. Crowding perceptions were significantly
different across the user groups. More than 50% of local residents perceived the national park as crowded, whereas only 27%
of regional visitors and 19% of tourists reported such an evaluation. Even among local residents and regional visitors, respondents
with more on-site experience expressed a greater impression of a crowded park. Differences in crowding evaluations between
local rural and urban residents and between regional rural and urban visitors were not found. For 27% of local residents and
15% of regional visitors, use levels were so unacceptable that they displaced temporally and spatially, whereas use displacement
was relatively irrelevant for tourists. The use displacement strategies involved differ among the three user groups. Management
implications were discussed, taking the specific situation of the small national park on the urban-rural fringe into consideration. 相似文献
102.
Ricardo Braun 《Environment, Development and Sustainability》2008,10(1):19-39
The implementation of sustainable development requires several support instruments. One of the major instruments in the Rio
Declaration to support this process has been environmental assessment that has been given considerable emphasis as to its
potential ability to help achieve more sustainable forms of development.
Regional environmental assessment (REA) has shown to be effective in supporting local sustainable development process. Selected
environmental assessment methods have been␣used to improve the REA exercise and provide reliable data for decision-making
not only to correct environmental problems due to past unsustainable social-economic developments but also help local governments
to implement Agenda 21 (AG21) plans and projects. 相似文献
103.
研究改进了棉铃虫中期预报方法;提出“一代监测、二代保顶、三代保蕾、四代保铃”为主的防治策略;研究制定适用于不同世代、不同水肥条件的科学防治指标,协调应用多种配套措施保护、利用自然天敌控害,系统监测和治理棉铃虫抗药性;利用棉花种质资源和品种的抗病、抗虫性;诱杀成虫;组建大面积综防技术体系。在1992~1995年棉铃虫猩獗发生的情况下,于河南省新乡县棉花病虫害综防示范区大面积实施后,有效控制了棉铃虫危害。 相似文献
104.
C. L. Hwang J. L. Williams R. Shojalashkari L. T. Fan 《Journal of the American Water Resources Association》1973,9(6):1159-1181
ABSTRACT: A river basin-wide water quality management system is considered. The river receives thermal as well as organic wastes. At-source treatment of these pollutants is imposed to control the basin-wide water quality. The related water quality standards are: the minimum DO concentration, the maximum allowable BOD concentration, the maximum allowable stream temperature, and the allowable rise in stream temperature. The general dynamic mathematical model representing water quality in streams and the thermal effects on BOD and DO concentrations is presented. The model is highly nonlinear in nature. The optimal management problem involving the model is solved by a recently developed nonlinear propgramming technique - the generalized reduced gradient (GRG) method. Comparison of results obtained by the GRG method vs. dynamic programming, and of results using a more realistic mathematical model vs. a simple model are presented. The analysis procedure can be applied to designing new and examining existing water quality programs, and to study the influence of alternate policies and constraints. 相似文献
105.
Larry F. Land 《Journal of the American Water Resources Association》1980,16(6):1041-1048
ABSTRACT: Four dam-break models were selected for testing with an observed data set from the November 6, 1977, disaster at Toccoa Falls, Georgia. The Kelly Barnes Dam failure occurred with a 35-ft head of water and produced a peak discharge of 23,000 ft3/s. The selected models included: (1) Modified Puls (MP), (2) U. S. Army Corps of Engineers Gradually Varied Unsteady Flow Profiles (USTFLO), (3) National Weather Service's Dam-Break Flood Forecast (DBFF), and (4) U. S. Geological Survey's method of characteristics (MOC) coupled with a general purpose streamflow simulation (J879DB). Achieving a successful simulation was easiest with the MP model. The DBFF model required a moderate effort while the MOC-J879DB models required some data alterations and considerable effort. The USTFLO model failed to simulate this test case. In the stream segment near the dam, the computed peak stages were generally within 5 feet of the observed high water marks. Elsewhere, the peak stage results were much better, generally within 2 feet. The peak discharges computed by the models were generally within 20 percent of discharges estimated by slope area and contracted opening measurements, except near the dam where the MOC-J879DB model's results was 80 percent too high. 相似文献
106.
W.M. Snyder W.C. Mills W.G. Knisel 《Journal of the American Water Resources Association》1978,14(1):83-98
Abstract: An ordered set of probability sensity functions was derived form transforms of the normal distribution. Variate transforms are based on orders of exponentiation. The set of distributions includes the log-normal. a partial basis for use of these functins in hydrology is demonstrated by establishing some required properties. A concept of mixed samples of zero and nonzero elements forming nonseparable sets of virtual and real elements is introduced to establish a physical lower limit of sampled diata independent of functional bounds. 相似文献
107.
本文应用灾害系统基本单元理论,以湖南省农业自然灾害为例,在地理信息系统支持下,将湖南省农业自然灾害系统划分为32524个基本单元。进而,以民政部1978~1993年农业灾情统计数据为标准,通过多因子逐步回归的方法,建立了反映湖南省多年平均状况的五种主要农业灾害灾情模型。最后,以灾害基本单元为最小空间分异单位,对综合农业灾情分异规律进行了探讨,并首次提出了基于自然单元的湖南省综合农业灾情的分异规律首先是受地势控制的东西分异的主要结论。 相似文献
108.
ENVIRONMENTAL AUDITING: A Synoptic Approach for Assessing Cumulative Impacts to Wetlands 总被引:1,自引:0,他引:1
/ The US Environmental Protection Agency's Wetlands ResearchProgram has developed the synoptic approach as a proposed method forassessing cumulative impacts to wetlands by providing both a general and acomprehensive view of the environment. It can also be applied more broadly toregional prioritization of environmental issues. The synoptic approach is aframework for making comparisons between landscape subunits, such aswatersheds, ecoregions, or counties, thereby allowing cumulative impacts tobe considered in management decisions. Because there is a lack of tools thatcan be used to address cumulative impacts within regulatory constraints, thesynoptic approach was designed as a method that could make use of availableinformation and best professional judgement. Thus, the approach is acompromise between the need for rigorous results and the need for timelyinformation. It is appropriate for decision making when quantitative,accurate information is not available; the cost of improving existinginformation or obtaining better information is high; the cost of a wronganswer is low; there is a high demand for the information; and the situationcalls for setting priorities between multiple decisions versus optimizing fora single decision. The synoptic approach should be useful for resourcemanagers because an assessment is timely; it can be completed within one totwo years at relatively low cost, tested, and improved over time. Anassessment can also be customized to specific needs, and the results arepresented in mapped format. However, the utility of a synoptic assessmentdepends on how well knowledge of the environment is incorporated into theassessment, relevant to particular management questions.KEY WORDS: Cumulative impact assessment; Landscape ecology; Regionalprioritization 相似文献
109.
以区域经济学为基础,灾害学为主导,应用层次分析原理,分析了山西省自然灾害对区域经济发展的影响,评价了不同区域的灾害严重程度及主要灾种,将全省划分为五大灾害经济区,为区域生产力布局提供了一些科学理论依据. 相似文献
110.
近五年中国自然灾害空间分布格局及其月动态变化研究 总被引:5,自引:7,他引:5
作者根据《中国减灾》所载1990~1994年月灾情记录,经统一编码和标准化处理,建立了以行政县为基本单元的数据库。进而对近五年来中国自然灾害空间分布及其月动态变化进行分析,并与1949~1990年中国自然灾害的平均状况进行对比。 相似文献