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971.
分析了渭河下游“95.8”洪水的特征;论述了出现小水量、高水位、大灾害的原因,提出了渭河下游及陕西三门峡库区的防汛对策。 相似文献
972.
973.
Barbara A. Rosensteel Peter F Strom 《Journal of the American Water Resources Association》1991,27(6):957-965
ABSTRACT: Sediments from the Pompton and Passaic Rivers at Two Bridges were analyzed for potentially available phosphorus fractions and total phosphorus (TP). Water samples from the same sites were analyzed for dissolved phosphorus, TP, suspended solids (SS), and volatile SS. Significant negative correlations between river TP concentrations and flow were observed. However, storm flows resulted in increases in TP and SS concentrations and flux (loadings). Most of the increase in river P loading at high flow was in the dissolved fraction, suggesting that the sediments may be a large source of dissolved P. Concentrations of potentially available P in the sediments ranged from 140 to 1310 times the TP concentration in the overlying water. According to a modified Vollenweider model, current P concentrations in the Pompton and Passaic Rivers will result in excessive P loading in the Wanaque Reservoir if even small volumes of river water are pumped to the reservoir through the recently completed Wanaque South pipeline. Reductions in sewage treatment plant effluent P concentrations alone will not produce sufficient decreases in river phosphorus concentrations to avoid this predicted overloading and eutrophication. 相似文献
974.
Robert C. Ostry 《Journal of the American Water Resources Association》1982,18(1):99-104
ABSTRACT: The Grand and Saugeen Rivers in southern Ontario were chosen for study as pilot watersheds under the Pollution From Land Use Activities Reference Group (PLUARG) study. The pilot watersheds have adjacent headwater areas and are physically similar in geology, physiography, and climate. Significant differences in water quality between the watersheds at their outlets are attributed to land use and population differences. The major pollutant sources in the two pilot watersheds were identified as trace elements from urban runoff and point source discharges; phosphorus from agricultural and urban runoff and private waste disposal; chloride from transportation corridors; and sediment and nitrogen from agricultural runoff. Yields at the watershed outlets were similar for suspended sediment and two to three times as high in the Grand River for phosphours, nitrogen, chloride, and lead. The higher phosphorus and nitrogen levels were attributed to larger point source inputs and the higher proportion of agricultural activity, comprising 75 percent of the Grand River basin compared to 64 percent in the Saugeen River basin. Similarly, the higher chloride and lead levels were attributed to an order of magnitude larger population and three times as much urban land in the Grand River basin compared to the Saugeen River basin. 相似文献
975.
Quantifying natural resource injuries and ecological service reductions: challenges and opportunities 总被引:1,自引:0,他引:1
The natural resource damage assessment (NRDA) provisions of the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) and the Oil Pollution Act (OPA) are complex and have been difficult to implement. The complexity and difficulty
in implementation arise both from the assessment procedures specified in agency NRDA guidance and from the limited ability
of ecologists to quantify impacts of hazardous substances on natural resources. This paper explores the scientific aspects
of NRDA implementation, and discusses conceptual and methodological relationships between NRDA and the much broader field
of ecological risk assessment (ERA). We discuss three critical components of the NRDA assessment approach: measuring natural
resource injuries and reductions in resource services; evaluating causality; and establishing baseline conditions. We identify
(1) specific approaches drawn from ERA practice that could improve each of these components, and (2) research needs and institutional
changes that may improve the ability of the NRDA process to achieve its stated objectives. We recommend the acceleration of
the ongoing dialogue among NRDA practitioners from the Trustee and PRP communities as a first step toward resolving the procedural
and technical deficiencies of the NRDA process. 相似文献
976.
Evaluating the characteristics of a set of sites as potential scientific research reserves is an example of land suitability
assessment. Suitability in this case is based upon multiple criteria, many of which can be linguistically imprecise and often
incompatible. Fuzzy logic is a useful method for characterizing imprecise suitability criteria and for combining criteria
into an overall suitability rating. The Ecosystem Management Decision Support software combined a fuzzy logic knowledge base
we developed to represent the assessment problem with a GIS database providing site-specific data for the assessment. Assessment
of sites as a potential natural reserve for the new University of California campus at Merced demonstrates the benefits of
fuzzy suitability assessment. The study was conducted in three stages of successively smaller assessment regions with increasingly
fine spatial resolution and specificity of criteria. Several sites were identified that best satisfy the suitability criteria
for a reserve to represent vernal pool habitat. 相似文献
977.
Refuting the paradigm of water services privatisation 总被引:1,自引:0,他引:1
The aim of this article is to question the fundamental assumptions behind privatisation and public–private partnerships. The article shows that instead of radically increasing private sector involvement, public sector reforms should be seriously considered. Public–private partnerships should be implemented so that the strengths of all the stakeholders may be fully utilised. 相似文献
978.
在有余热余湿的厂房 ,大多采用自然通风。笔者采用k ε紊流模型 ,对某钢铁公司二高线厂房自然通风消除热害进行了数值模拟。将生产线上的散热量作为能量方程的附加源项 ,计算厂房内的速度场和温度场 ,优选出了该热源厂房的通风改造方案 :进风口的标高降低 2m ,在操作平台上设置开孔率为 30 %的通风栅栏板。通过对通风改造前、后厂房内温度实测值的对比 ,厂房工作区平均温度下降 5℃ ,风速由原来的平均 0 .2m/s增加到 1.6m/s,厂房内作业区的热环境有明显改善 ,防止了因热环境问题造成的安全事故 ,提高了工人的生产效率。 相似文献
979.
Alan Miller 《Environmental management》1993,17(5):563-574
There is a continuing debate about the proper role of analytical (positivist) science in natural resource decision making.
Two diametrically opposed views are evident, arguing for and against a more extended role for scientific information. The
debate takes on a different complexion if one recognizes that certain kinds of problem, referred to here as “wicked” or “trans-science”
problems, may not be amenable to the analytical process. Indeed, the mistaken application of analytical methods to trans-science
problems may not only be a waste of time and money but also serve to hinder policy development. Since many environmental issues
are trans-science in nature, then it follows that alternatives to analytical science need to be developed. In this article,
the issues involved in the debate are clarified by examining the impact of the use of analytical methods in a particular case,
the spruce budworm controversy in New Brunswick. The article ends with some suggestions about a “holistic” approach to the
problem. 相似文献
980.
The importance of developing evaluative standards for judging the acceptability of impacts caused by recreation is common
to all recent natural resource management frameworks. A normative model has been advanced as a useful way to conceptualize,
collect, and organize empirical data representing standards for resource management issues. This article summarizes the findings
from social and ecological research to illustrate the utility of the normative approach from a manager's perspective. The
social data (e.g., encounter norms, proximity norms, and tolerances for launch wait times) were obtained from 13 different
study sites, while the ecological data (e.g., tolerances for the amount of bare ground, size of fire rings, instream flows,
and wildlife management practices) were collected at three specific sites and from one statewide survey, Findings from the
social research indicated that encounter norms exist for particular types of contacts with certain types of visitors at particular
places and for certain types of experiences. The recreationists reported norms for acceptable distances between individuals,
encounters with others at campsites or attractions, and waiting times to run rapids. These social norm evaluation techniques
were also shown to be transferable to normative evaluations of ecological impacts. The users had opinions about ecological
impacts and were willing to express them. In addition, the ecological norms were of moderate to high intensity. It is argued
that the usefulness of normative approaches lies in their ability to characterize group agreement about appropriate use conditions
or impact levels for a particular recreation experience, thus providing the evaluative information needed to establish management
standards. 相似文献