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931.
据沁河流域九女台洪水题刻水位及相关历史文献记载,沁河流域1482年洪水洪峰流量极大,历时甚长,与该流域一般洪水过程的差异迥然.通过地貌调查,并利用14C测年等方法,对沁河九女台河段进行了详细研究,发现其1482年高洪水位是梯沟口泥石流-崩塌堆积物堰塞沁河主河道的结果.当年由于降雨,使梯沟流域发生泥石流,并导致沟口右岸岩壁崩塌,形成堰塞坝,造成沁河河道阻塞,过水断面减小,九女台附近河段水位壅高,并保持了近40天的时间,堰塞坝最终溃决,导致沁河下游怀庆府发生严重的洪水灾害. 相似文献
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933.
Guofang Zhai Teruki Fukuzono Saburo Ikeda 《Journal of the American Water Resources Association》2005,41(1):77-92
ABSTRACT: In conventional flood damage reduction studies, flood damage is usually estimated with a damage function according to the depth of inundation. However, this method may not reflect the conditions of each family residing in the floodplain because it ignores not only the distribution of flood damage but also the effect of building characteristics and residents' preparedness. This paper uses data from a questionnaire based survey (N= 3,036) conducted 17 months after the Tokai Flood of 2000 that caused disastrous losses to household properties. It provides a conceptual “doughnut structure” model of flood damage to houses and house contents and a mathematical basis for models to explore the determinants of flood damage. Besides the inundation depth, house type significantly affects both the house structural and content damage probabilities, while house ownership and house structure affect house damage probability but not house content damage probability at a given depth. Inundation depth, residing period, and household income significantly affect both house and content damage values. In addition, house ownership has a significant impact on the house damage value, while house structure has an impact on content damage value. 相似文献
934.
USING GEOLOGY TO IMPROVE FLOOD HAZARD MANAGEMENT ON ALLUVIAL FANS ‐ AN EXAMPLE FROM LAUGHLIN,NEVADA1
P. Kyle. House 《Journal of the American Water Resources Association》2005,41(6):1431-1447
A study of the piedmont of the Newberry Mountains near Laughlin, Nevada, demonstrates that geologic information can improve the scientific basis of flood‐hazard management on alluvial fans in desert areas. Comparison of geologic information against flood insurance rate maps (FIRMs) reveals flaws in conventional methods for flood hazard delineation in this setting. Geologic evidence indicates that large parts of the Newberry piedmont have been isolated from significant flooding for at least the past 10,000 years. This contrasts with existing FIRMs that include large tracts of nonflood prone land in the 100‐year and 500‐year flood hazard zones and exclude areas of indisputably flood prone land from the regulatory flood plain. From the basis of the geology, flood hazards on at least one‐third of the piedmont are mischaracterized on the regulatory maps. The formal incorporation of geologic data into flood hazard studies on desert piedmonts could significantly reduce this type of discrepancy and substantially reduce the scope, hence cost, of more elaborate engineering studies and hazard mitigation strategies. The results of this study affirm the value of new Federal Emergency Management Agency (FEMA) recommendations for characterizing alluvial fan flood hazards and support an argument for mandating geological studies in the regulatory process. 相似文献
935.
936.
937.
水旱灾害对我国农业及社会经济发展的影响 总被引:4,自引:3,他引:4
水旱灾害首先影响到我国农业生产。粮食产量的大幅减产还会波及到整个国民经济及人民生活水平的下降。研究自然灾害不仅要注意因灾损失的自然因素,同时要联系造成灾害的社会、经济、人文因素等诸多方面进行自与非自然因素的综合分析。 相似文献
938.
939.
The Brahmaputra changes its course and pattern along with its current flow very frequently especially in its upper stretches and this has a strong bearing on its hydrobiology. The hydro-geological pattern of the Brahmaputra has resulted in a possible zonation of the river into five major types of fish habitat. Altogether 167 fish species have been recorded from the upper Brahmaputra of which about 30 percent may be considered as ornamental varieties. Again, according to their seasonal availability, the fish fauna has been grouped into four principal categories. Among all the hydrological factors, flood impulse is probably the strongest factor that regulates other limnological conditions and faunal distribution. Usually, there are three or four high floods between May and October and fish migration is intimately related to this flood regime. During the dry season fishing is mostly restricted to near the confluents of tributaries or channels and also at river meanders. However, large-scale felling of trees in the catchment areas and construction of embankments along the river banks have altered the riverine ecosystem drastically, as a result of which, the river has become heavily silted and the connecting channels of the floodplain lakes are also dammed. Consequently, fishes and other megafauna are deprived of adequate water cover, food supply and breeding grounds. An ecohydrological approach has been advocated for habitat restoration. 相似文献
940.
Molly M. Pohl 《Journal of the American Water Resources Association》2002,38(6):1511-1519
ABSTRACT: Over 76,000 dams have been constructed on American rivers to provide services such as flood protection, water storage, hydroelectric power, and navigation. Although most dams continue to provide sufficient benefits to retain the structure, dam removal is becoming increasingly common. This study involved the construction of a dam removal database to analyze spatial and temporal trends in dam removal. The data included information on 417 cases of dismantled American dams, 153 with known rationales for removal. Database analysis indicated that the leading purposes for dismantling structures are safety concerns and interest in environmental restoration. There is substantial geographic variability in dam removal rationales, with California leading in razing dams for environmental purposes, and Wisconsin leading in economic and safety rationales. States with substantial removals tend to have programs that support and fund dam razing. Although removals for safety reasons have been increasing steadily in the past three decades, environmental removals made a rather dramatic and sudden entry into the dam removal arena in the 1990s. Analysis of spatial and temporal trends in dam razing are of particular significance given the likely increase in dam removals in the 21st Century. 相似文献