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631.
632.
现代海底热水活动是当前地球系统科学研究的一个重要组成部分,它是研究海底地质作用体系中的一个关键环节。海底的构造作用、岩浆活动等因素制约了热水循环的发育和活动规律,而热水活动又直接或间接地产生了一些地质效应,如海底的热水喷流成岩成矿效应,此外它还与海底的热能输导与转化、海洋化学组分特征、海洋生命和生命起源等现象有着密切的成因联系。开展现代海底热水活动的系统性研究,应注重将热水循环的内部动力学机制和热水活动所引发的外部环境效应相结合,为此我们把它初步展开为:热水循环的空间组构研究、热量输导作用研究、热水流体的化学成分研究、热水活动与极端生命的关系研究以及热水活动的生命周期研究等 5个方面,分别解析其内部特征以及引发的环境效应。最后初步探讨了开展海底热水活动的系统性研究的科学意义。 相似文献
633.
This article evaluates some of the factors which limit the human benefits of hazard warnings, with specific reference to flood
warnings, and we conclude by suggesting ways of enhancing these benefits. We focus mainly upon the economic benefits generated
by flood damage savings by households that warnings facilitate; health effects of flooding and flood warnings; and the effects
of warnings on loss of life and physical injury. Our results, based partly upon surveys of flooded households, reveal that
economic benefits are currently more limited than we previously thought, but that for several reasons these benefits are likely
to be under-estimated. We argue that the intangible benefits to public health, safety and security must also be taken into
account in decisions about investment in flood warnings. In England and Wales, the public’s response to flood warnings is
currently low and is a key benefit-limiting factor which could begin to undermine a recent major shift in national flood risk
management policy towards a more people-centred, portfolio approach in which changing human behaviour is viewed as important.
Using a trans-disciplinary approach, we discuss the evidence and literature surrounding this poor response, and suggest a
number of ways in which the issue may be addressed in future. 相似文献
634.
《The Professional geographer》1991,43(1):108-114
Electromap World Atlas , Version 1.1. Interactive Population Statistical System , Version 1.0. Jerry W. Wicks and Jose Luiz Pereira de Almeida MATHCAD , Version 2.5. Memory Mate. Micro DEM +, Version 5.21. Peter Guth NCSS – Number Cruncher Statistical System , Version 5.02. Dr. Jerry L. Hintze 相似文献
635.
Global Perspectives on Loss of Human Life Caused by Floods 总被引:14,自引:4,他引:10
Every year floods cause enormous damage all over the world. This study investigates loss of human life statistics for different types of floods and different regions on a global scale. The OFDA/CRED Database contains data on international disasters and is maintained by the Centre for Research on the Epidemiology of Disasters in Brussels (CRED) in cooperation with United States Office for Foreign Disaster Assistance (OFDA). Information from this source on a large number of flood events, which occurred between January 1975 and June 2002, is evaluated with respect to flood location and flood type. Due to the limited availability of information on coastal flood events, the scope of this study is limited to three types of freshwater flooding: river floods, flash floods and drainage problems. First, the development of loss of life statistics over time is discussed. Second, the dataset is analysed by region, by flood type and by the combination of type and region. The study shows that flash floods result in the highest average mortality per event (the number of fatalities divided by the number of affected persons). A cross analysis by flood type and location shows that average mortality is relatively constant for the different types over various continents, while the magnitude of the impacts (numbers of killed) and affected for a certain type varies between the different continents. On a worldwide scale Asian river floods are most significant in terms of number of persons killed and affected. Finally, a comparison with figures for other types of natural disasters shows that floods are the most significant disaster type in terms of the number of persons affected. 相似文献
636.
A. Nicolaidou 《Estuarine, Coastal and Shelf Science》1983,17(1):31-43
Growth, survivorship, reproduction and productivity of a Pectinaria (Lagis) koreni population was studied in Colwyn Bay, from July 1975 to August 1976. The cephalic disc diameter of the worms was chosen as an index of size, after the relations between linear and weight measurements of the body were established. Settlement of Pectinaria was estimated to have occured at the beginning of June, and the whole population had disappeared by April. Growth was initially fast but it ceased completely during the winter, probably due to low temperatures and disturbance by storms. Bundles of gametes first appeared in the coelomic fluid in November, but maturation was not completed before May. Mature ova, 60–65 μ in diameter, were released individually: sperms, a few microns in diameter, were released in bundles. The highest standing crop, 47·5 g m?2 was present in September and the total production of the cohort during its lifetime was 138·8 g m?2. The ratio between total production and mean biomass was given by P/B: 7·3. 相似文献
637.
l 1NTRODUCTIONAs the sediment cAned by the river gets dePositOd in the reservoir, there is a pro gressive reduction in itscaPacity to hold water. For examPle the Zuni reservoir on river Zuni, a tributary of the little ColoradO atBlack rock, New Mexico, U.S.A., lost aboat 75% caPacity in just 20 years. Sindlary, just in l0 years theIchari reservoir on river Tons, a tribUtary of river Yamuna (Inda), reduced to about l5% of its originalcaPacity. Thus, at the planning stage, one must … 相似文献
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