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91.
Risk Assessment,Emergency Preparedness and Response to Hazards: The Case of the 1997 Red River Valley Flood,Canada 总被引:1,自引:0,他引:1
The prevention and/or mitigation offlood disasters requires continual research, numerouscapital investment decisions, and high-qualitymaintenance and modifications of flood-controlstructures. In addition, institutional and privatepreparedness is needed. The experience offlood-control in North America has shown mixedoutcomes: while flood frequency has declined duringthe last few decades, the economic losses havecontinued to rise. Recent catastrophic floods havealso been linked to major structural interventions inthe region. The flood diversions may cause harmfuleffects upon the floodplain inhabitants by influencingflood levels in areas which are not normallyflood-prone. The increasing vulnerability of thefloodplain inhabitants poses new challenges and raisesquestions concerning the existing risk assessmentmethods, institutional preparedness and responses todisaster-related public emergencies, and local-levelpublic involvement in flood mitigation efforts.In the context of the catastrophic 1997 floods of theRed River Valley, Manitoba, Canada, this researchfocuses on two aspects of flood-related emergencygovernance and management: (i) the functions andeffectiveness of control structures, and (ii) theroles, responsibilities and effectiveness oflegislative and other operational measures. The studyconcludes that the flood-loss mitigation measures,both in terms of effects of control structures andinstitutional interventions for emergency evacuation,were not fully effective for ensuring the well-beingand satisfaction of floodplain inhabitants. Althoughorganizational preparedness and mobilization to copewith the 1997 flood emergency was considerable, theirsuccess during the onset of the flood event waslimited. Lack of communication and understandingbetween institutions, a reluctance to implementup-to-date regulations, and minimal publicparticipation in the emergency decision-making processall contributed to the difficulties experienced byfloodplain inhabitants. 相似文献
92.
中国红土期气候构造期的耦合 总被引:16,自引:0,他引:16
红土发育、气候变化、构造活动之间存在旋回、周期、因果、主次、配置等耦合关系。其中旋回和周期,以红土发育的阶段性为标志,突出一个“期”字。通过探讨红土旋回与季风发展期、冰期间冰期、新构造期、构造活动期等的对应关系,可以将我国第四纪分为3个构造-气候(红土)主旋回。 相似文献
93.
Zhao-Yin WANG Yongsheng WU and Guangqian WANG Prof. Dept. of Hydraulic Engineering Tsinghua University & International Research Training Center on Erosion Sedimentation Beijing China Email: zywang@tsinghua.edu.cn or zywang@sun 《国际泥沙研究》2001,16(4)
1 mTRoorcnoxThe EnvirDment AgenCy of UK (l997) defins eUtIDPhication as "the enrichInnt of waters byinorgedc plant nUtrientS that result in the simulation of an mp Of syInPtOInati changes. These includethe inCrased PrOduCtiOn Of aigae or othe aquatic PlantS, affeChng the quallty of the water and distUIbingthe balance Of orpedsms Present within it. Such changes Inay be undesirable and intetw with wateuses." Sndth et al. (l999) indicated tha eopation of waters is mainly caused by h… 相似文献
94.
青藏高原东北部古喀斯特过程与环境 总被引:6,自引:0,他引:6
本文介绍了青藏高原东北部地区的古喀斯特现象,并对相关沉积进行了化学成、粘土矿物的X-射线衍射以及石英砂表面结构等气候代用指标的分析。分析结果一致,指示了温暖湿润的亚热带气候条件。重结晶方解石的裂变径迹测年结果表明,该地区古喀斯特发育于中中新世。 相似文献
95.
The state of knowledge of the Central European water mite fauna and the research history are briefly surveyed. Several areas for which we are provided with rich data sets are of high value for the monitoring of faunistic trends on the background of local and global environmental change. The need for a database combining historical and actual faunistic information is stressed. It should facilitate the access to all data from former times, give a survey on actual activities by regular updates, and help for a better organization of future research activities. On the base of an update of the Limnofauna Europaea (K.O. Viets 1978, Gerecke in www.watermite.org) a first attempt is made to (1) recognize changes in the Central European fauna during the past 100 years; (2) emphasize species which may be endangered or have disappeared during the past 100 years. At the present state of knowledge, the degree of threat to water mite species in this area is best calculated from their preference for particular habitat types which are rare and in danger to disappear in cultivated landscapes. Our knowledge concerning neozoic water mites in the study area is discussed. 相似文献
96.
Rita A. M. Gardner 《地球表面变化过程与地形》1981,6(5):459-468
Thin section, SEM, and TEM analyses have indicated that the red ‘teri’ sands of southeast India have formed from weathering in situ of coastal dune sands. The data does not support a detrital origin for the red sands. C14 dates indicate that dune deposition and weathering, to a maximum depth of 10 m, leading to the formation of a hematite, koalinite and illite rich matrix has taken place rapidly over the past 25,000 years. It is postulated that garnet was a major source of hematite (ferric oxide). 相似文献
97.
98.
WEN Lingjuan LU Huayu & QIANG Xiaoke State Key Laboratory of Loess Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China 《中国科学D辑(英文版)》2005,48(9):1452-1462
In recent years, the Red Clay deposits underlying Quaternary loess on the Chinese Loess Plateau (north China) have attracted more attention because they show a direct and continuous record of past atmos- pheric circulation and palaeoclimatic change. Investiga- tions on Red Clay deposits through multidisciplinary methods have demonstrated an aeolian origin for the Red Clay, like the overlying Quaternary loess. The Red Clay formed during the Miocene and Pliocene[1―13]. However, the type o… 相似文献
99.
The Day Nui Con Voi belt in Vietnam is the southeasternmost part of the Red River shear zone in Asia. It is a narrow high-grade metamorphic core complex consisting of garnet–sillimanite–biotite gneisses, mylonite bands, amphibolite layers and migmatites. Geothermobarometric study of the complex revealed that the peak metamorphism took place under amphibolite-facies conditions of 690−60+30°C and 0.65±0.15 GPa and the subsequent mylonitization occurred under greenschist-facies conditions of 480°C and under 0.3 GPa. Fifteen synkinematic hornblende and biotite separates from gneisses, amphibolites and mylonites were dated with the K/Ar method. Hornblende separates from the Day Nui Con Voi give K–Ar ages of 26.4–28.5 Ma, and the biotite separates do give 24.5–24.7 Ma. Combination of thermobarometric and geochronological data yields the cooling history of 500°C at 28 Ma and 300°C at 24 Ma with a cooling rate of 70–110°C Ma−1, and 23 km post-metamorphic exhumation of the core complex. The first 16 km exhumation from the peak of metamorphism (at probably 31 Ma) to 28 Ma was triggered by the left-lateral strike-slip displacement of the Red River shear zone. 相似文献
100.
We present the first diffraction-limited K-band image of the Red Rectangle with 76 mas resolution, an H-band image with 75 mas resolution, and an RG 715 filter image ( 800 nm wavelength) with 78 mas resolution (corresponding to 25 AU for a distance of 330 pc). The H and K images were reconstructed from 6 m telescope speckle data and the RG 715 image from 2.2 m telescope data using the speckle masking bispectrum method. At all wavelengths the images show a compact, highly symmetric bipolar nebula, suggesting a toroidal density distribution of the circumstellar material. No direct light from the central binary can be seen as it is obscured by a dust disk or circumbinary torus. Our first high-resolution H−K color image of the nebula shows a broad red plateau of H−K≈ 2m in the bright inner regions.The optical and near-infrared images and the available photometric continuum observations in a wide range of ultraviolet to centimeter wavelengths enabled us to model the Red Rectangle in detail using a two-dimensional radiative transfer code. Our model matches both the high-resolution images and the spectral energy distribution of this object very well, making the following picture much more certain. The central close binary system with a total luminosity of 3000 L is embedded in a very dense, compact circumbinary torus which has an average number density nH ≈5×1012 cm−3, an outer radius of the dense inner region of R≈30 AU (91 mas), and a ρ∝r−2 density distribution. The full opening angle of the bipolar outflow cavities in our model is 70°. By comparing the observed and theoretical images, we derived an inclination angle of the torus to the line of sight of 7°±1°.The radiative transfer calculations show that the dust properties in the Red Rectangle are spatially inhomogeneous. The modeling confirms that the idea of large grains in the long-lived disk around the Red Rectangle (Jura et al., 1997 [ApJ, 474, 741]) is quantitatively consistent with the observations. In our models, unusually large, approximately millimeter-sized grains dominate the emission of the compact, massive torus. Models with smaller average grain sizes can possibly be found in future studies, for instance, if it turns out that the radio spectrum is not mainly caused by continuum dust emission. Therefore, the large grains suggested by our models require further confirmation by both new observations and radiative transfer calculations. Assuming a dust-to-gas ratio ρd/ρg of 0.005, the dense torus mass is 0.25 M. The model gives a lower limit of 0.0018 M, for the mass of the large particles, which produce a gray extinction of A≈ 28m, towards the center. A much smaller mass of submicron-sized dust grains is presumably located in the polar outflow cavities, their conical surface layers, and in the outer low-density parts of the torus (where ρ∝r−4, in the region of 30 AUr 2000 AU corresponding to 0.′′09–6′′). 相似文献