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11.
河口切变锋引起的滩槽泥沙交换效应 总被引:3,自引:1,他引:2
朱慧芳 《长江流域资源与环境》1995,4(1):54-57
切变锋是河口湾锋系中最为常见和最易观察到的锋面类型。本文对长江口的切变锋进行现场观察和滩,槽同步水文资料分析,简述了长江口切变锋发生的部分和基本特性,提出了切变锋引起的滩,槽泥沙呈现螺旋形交换形式等论点。 相似文献
12.
三峡库区水土流失特点及其环境危害防治措施探讨 总被引:15,自引:0,他引:15
水土流失是三峡库区主要环境问题之一,也是库区产生大量泥沙的根本因素,更是造成库区人民生活贫困的根源。本文就三峡库区水土流失的特点及其环境危害作了分析,提出了相应的防治措施,为水土流失防治工程提供科学依据。 相似文献
13.
Alonso R Elvira S Sanz MJ Gerosa G Emberson LD Bermejo V Gimeno BS 《Environmental pollution (Barking, Essex : 1987)》2008,155(3):473-480
A sensitivity analysis of a proposed parameterization of the stomatal conductance (g(s)) module of the European ozone deposition model (DO(3)SE) for Quercus ilex was performed. The performance of the model was tested against measured g(s) in the field at three sites in Spain. The best fit of the model was found for those sites, or during those periods, facing no or mild stress conditions, but a worse performance was found under severe drought or temperature stress, mostly occurring at continental sites. The best performance was obtained when both f(phen) and f(SWP) were included. A local parameterization accounting for the lower temperatures recorded in winter and the higher water shortage at the continental sites resulted in a better performance of the model. The overall results indicate that two different parameterizations of the model are needed, one for marine-influenced sites and another one for continental sites. 相似文献
14.
15.
Frank Eierdanz Joseph Alcamo Lilibeth Acosta-Michlik Dörthe Krömker Dennis Tänzler 《Regional Environmental Change》2008,8(4):197-205
This paper presents the technical aspects of a new methodology for assessing the susceptibility of society to drought. The
methodology consists of a combination of inference modelling and fuzzy logic applications. Four steps are followed: (1) model
input variables are selected—these variables reflect the main factors influencing susceptibility in a social group, population
or region, (2) fuzzification—the uncertainties of the input variables are made explicit by representing them as ‘fuzzy membership
functions’, (3) inference modelling—the input variables are used to construct a model made up of linguistic rules, and (4)
defuzzification—results from the model in linguistic form are translated into numerical form, also through the use of fuzzy
membership functions. The disadvantages and advantages of this methodology became apparent when it was applied to the assessment
of susceptibility from three disciplinary perspectives: Disadvantages include the difficulty in validating results and the
subjectivity involved with specifying fuzzy membership functions and the rules of the inference model. Advantages of the methodology
are its transparency, because all model assumptions have to be made explicit in the form of inference rules; its flexibility,
in that informal and expert knowledge can be incorporated through ‘fuzzy membership functions’ and through the rules in the
inference model; and its versatility, since numerical data can be converted to linguistic statements and vice versa through
the procedures of ‘fuzzification’ and ‘defuzzification’. 相似文献
16.
Surveys of water recreational activities were conducted in the Peel-Harvey estuary. Channels used by recreationists to gain information about water quality, the perception of water quality and resulting behaviour were investigated. This study showed that personal perception, local knowledge and history, absence of warnings and residency were major factors contributing to risk perception and behaviour in this recreational community. Management strategies should take this information into account to achieve maximal outcomes. 相似文献
17.
Almeida CA Quintar S González P Mallea MA 《Environmental monitoring and assessment》2007,133(1-3):459-465
A study of the water quality of the Potrero de los Funes River (San Luis – Argentina) was carried out in order to evaluate
the possible effect of the anthropogenic activities on the river developed in the homonymous town. Samples were collected
during the period March 2000–November 2005 at three selected sampling sites (RP1, RP2 and RP3). Different physicochemical and bacteriological parameters (turbidity, pH, conductivity, suspended solids, alkalinity, potassium,
sodium, calcium, magnesium, chlorides, nitrates, phosphates, sulphates, chemical oxygen demand (COD), 5-day biological oxygen
demand (BOD5), dissolved oxygen, total coliforms, Escherichia coli and total heterotrophic bacteria) were analysed according to the Standard Method for the Examination of Water and Wastewater.
When comparing the values of total coliforms, E. coli, total heterotrophic bacteria, COD, BOD5 and phosphates from the zone without anthropogenic influence (RP1) and the urban zones (RP2 and RP3) an important variation in the parameters was observed. These results indicate that the urban activity produces a serious
and negative effect on the water quality, thus constituting a sanitary risk and may have a major impact on the trophic status
of the Potrero de los Funes dam. As case study, we report on the use of General Quality Index (GQI) to evaluate spatial and
seasonal changes in the water quality of Potrero de los Funes River. Results revealed a significant degradation of the water
quality at RP2 and RP3. 相似文献
18.
重点开发长江是90年代中国经济重大战略布署。将长江产业带建设成具有强大经济实力的国家一级经济轴线,宜采用分层次推进与中心辐射相结合的发展战略,以浦东开发和三峡建设为契机,加强基础产业,发展新兴产业和第三产业,优化产业结构,以能源和交通建设先行,改善基础设施。同时,要协调产业带建设与浦东开发、三峡工程建设的关系。 相似文献
19.
本文从柑桔冻害和热害的危害因子和指标等级划分的研究和选取入手,着重探讨了长江三峡地区(湖北境内)两害显著的时空变化特征、差异与关联性及对柑桔生产的影响;揭示了80年代以来冬暖春热的重大气候变化是使两害向“两极分化”的根本原因;讨论了三峡水利工程对两害时空格局的可能调整及减灾原理;最后提出了可能的对策。 相似文献
20.
Dario Paladini Maria Giovanna Russo Antonio Tartaglione Annamaria Loffredo Pasquale Martinelli 《黑龙江环境通报》2002,22(13):1185-1187
Toriello–Carey syndrome is a rare malformative complex, described for the first time in 1988, characterized by agenesis of the corpus callosum, facial anomalies, cardiac defects and hypotonia. Relatively few neonatal cases have been reported. We describe here the first prenatal ultrasound diagnosis of the syndrome based on the detection of agenesis of the corpus callosum and spongious cardiomyopathy in a 22-week-old fetus of a couple with positive family history. The first sib of the couple was diagnosed with Toriello–Carey syndrome at 1 year of age, and had, in addition to the typical facial anomalies not detectable by ultrasound, agenesis of the corpus callosum and the same heart lesion (spongious cardiomyopathy). This report demonstrates that prenatal diagnosis of Toriello–Carey syndrome is feasible in the second trimester of pregnancy. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献