共查询到20条相似文献，搜索用时 30 毫秒
1.
Donald A. Wilhite 《Natural Hazards》1996,13(3):229-252
Drought is a normal, recurrent feature of climate that affects virtually all countries to some degree. The number of drought-induced natural disasters has grown significantly since the 1960s, largely as a result of increasing vulnerability to extended periods of precipitation deficiency rather than because of an increase in the frequency of meteorological droughts. This increase in drought-induced natural disasters has resulted in a considerable growth of interest in drought mitigation and preparedness worldwide. The purpose of a national preparedness plan is to reduce societal vulnerability to drought through the adoption of preventive, anticipatory policies and programs. This paper describes a ten-step planning process that nations can follow to develop a drought preparedness plan. This process, originally developed in 1987, has been the basis of discussions at training seminars on drought preparedness for developing nations in Africa, Asia, and Latin America. It has also been adopted, with appropriate modifications, by state or provincial governments and by municipalities. The process is intended to be flexible so that governments can add, delete, or modify the suggested steps, as necessary.Published as Paper No. 10946, Journal Series, Nebraska Agricultural Research Division. The work reported here was conducted under Nebraska Agricultural Research Division Project 27-007. This material is based in part upon work supported by the National Science Foundation under Grant ATM-8704050. 相似文献
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Drought risk assessment in the western part of Bangladesh 总被引：14，自引：8，他引：6
Though drought is a recurrent phenomenon in Bangladesh, very little attention has been so far paid to the mitigation and preparedness
of droughts. This article presents a method for spatial assessment of drought risk in Bangladesh. A conceptual framework,
which emphasizes the combined role of hazard and vulnerability in defining risk, is used for the study. Standardized precipitation
index method in a GIS environment is used to map the spatial extents of drought hazards in different time steps. The key social
and physical factors that define drought vulnerability in the context of Bangladesh are identified and corresponding thematic
maps in district level are prepared. Composite drought vulnerability map is developed through the integration of those thematic
maps. The risk is computed as the product of the hazard and vulnerability. The result shows that droughts pose highest risk
to the northern and northwestern districts of Bangladesh. 相似文献
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《第四纪科学杂志》2017,32(8):1112-1120
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对区域干旱的概念和计算方法进行了研究,认为干旱问题应根据不同的干旱特征分区进行研究并提出针对性的解决措施。干旱研究不仅要考虑到干旱的水文特征,而且要考虑干旱风险所带来的后果。提出了分析干旱问题的理论框架。并将黄河下游引黄灌区划分为6个子区,应用多变量随机模型生成了月降水量资料系列。利用了33年的月降水量资料率定模型参数。应用生成的月降水量系列从理论风险性的观点研究了区域干旱问题。 相似文献
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E. Olukayode Oladipo 《Natural Hazards》1993,8(2):171-188
A long-period instrumental data set (1916–1987) of monthly growing season (April–October) rainfall totals for 34 stations in northern Nigeria is used to quantify drought following the method of H. N. Bhalme and D. A. Mooley. It is established that there are remarkable seasonal changes in the patterns of wetness and dryness over the region with no consistent recurrent spatial patterns in the moisture anomalies. In general, large-scale droughts only rarely cover the region as a whole, and there are distinct spatial differences dominating the wet and dry years. The length and severity of drought varies from sub-area to sub-area with very low interannual persistence. Although discrete areas do catch the brunt of drought on a year-by-year basis, drought occurrence in the region is largely sporadic in its spatial distribution. The rather noisy spatial characteristics of drought in northern Nigeria suggests that the seasonal shift in the Intertropical Discontinuity (ITD) is not likely the most important causal mechanism of drought in the region. 相似文献
7.
为了认识淮河流域过去500年洪旱事件发生规律并鉴别当前的洪旱情势,收集并对比分析了流域实测降雨资料、重建历史雨季降雨资料、历史旱涝等级资料、历史洪旱文献记录和历史调查洪水资料等多源洪旱灾害数据。以重建历史雨季降雨资料和历史旱涝等级资料为主要依据,通过滑动平均、频率计算、小波分析和突变检验等方法,分析流域过去500年洪水干旱时空分布特征和演变规律。结果表明,17世纪淮河流域洪旱灾害最严重,但20世纪极端洪旱事件发生频次最多。淮河流域洪旱事件存在40年左右的稳定长周期,主周期从18世纪的15~20年逐渐减少到19世纪的5年周期,近20年来出现2~3年的主周期,洪旱灾害事件呈增加趋势,流域社会经济发展面临着严峻的洪旱灾害威胁。 相似文献
8.
This study analyses regional drought characteristics (frequency, severity, and persistence) of meteorological droughts occurred in the northwestern parts falling under arid and semiarid regions of India with mean annual rainfall ranging between 100 and 900 mm. A drought is defined as a season or a year with rainfall less than 75% of corresponding mean at a place. Long-term monthly rainfall records (1901–2013) of 90 districts of north-west India located in the states of Punjab, Haryana, Rajasthan and Gujarat are used in the analysis. The percentage departure of seasonal rainfall from long-term average rainfall has been used for identification of onset, termination, and quantification of drought severity. The average frequency varied from once every 3–4 years. The westerly districts have an average drought return period of 3 years, while districts lying toward the east had droughts once every 4 years. Only four of the 90 districts in the study area experienced droughts once every 5 years. Persistent droughts of 2, 3, and 4 year duration occurred widely. Severe droughts occurred in the years 1904, 1905, 1911, 1918, 1931, 1939, 1985, 1986, 1987, 1993, and 2002, with an average frequency of severe drought events of one in 10 years. The analysis presented in this paper improves understanding of the regional drought characteristics and will inform drought mitigations and strategies in these arid and semiarid areas. 相似文献
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Spatial and temporal pattern of precipitation and drought in Gansu Province, Northwest China 总被引：8，自引：3，他引：5
Drought is one of the most harmful natural hazards in Gansu Province in Northwest China. The changes of precipitation affect
the severity of drought. In order to recognize the trend of precipitation and understand the effect of rainfall change on
water resources management and drought severity, Mann–Kendall test was used. Standardized Precipitation Index (SPI) was calculated
to reconstruct the drought at different time scales and analyze the frequency of drought occurrence in the recent 50 years.
The results show that the SPI is applicable in Gansu Province. The number of severe droughts differs among regions: it is
more obvious as a 3-month drought in the Yellow River Basin and the Yangtze River Basin than in the Inland River Basin, and
other droughts at 6-, 9-, and 12-month time scales have the same effect in the three regions. Mann–Kendall test results show
that there is an upward trend in the summer periods and a downward trend in the autumn-winter-spring intervals ranging from
10.5 mm/10 years to −37.4 mm/10 years, which affect the local water resources management, droughts mitigation, and agriculture
decision making. This situation poses challenges for future study. 相似文献
13.
Water-deficit-based drought risk assessments in Taiwan 总被引：1，自引：0，他引：1
Taiwan is located in Western Pacific and receives approximate 2,500?mm rainfall per year. Suffered from inadequate water supply during prolonged and severe droughts, assessing drought risk becomes one of the key tasks of water-resources planning and management in Taiwan. Well-prepared drought mitigation measures require assimilation of physical environment of droughts and human socioeconomic factors. An index-based approach is presented in this study to evaluate drought risk at municipal scale in Taiwan for current status (2008) as well as future scenarios (2021). A multiplicative formula links drought hazard (frequency, duration, and severity of droughts), drought exposure (water use), and drought vulnerability (unreliable water supply) to determine drought risk. This approach quantifies the spatial distribution of drought risk and is able to deal with future changes of water use and water-supply source and to examine their influences on drought risk assessments. The results reveal that the regions that are at great risk in the future are those regions already threaten by drought currently. Changes of future water use and water-supply source would not significantly alter spatial distribution of drought risk and ranking order among regions. These results present a basis for future water-resources planning and economic developments for each municipal region. 相似文献
14.
Andrej Čerňanský Davit Vasilyan Georgios L. Georgalis Peter Joniak Serdar Mayda Jozef Klembara 《Swiss Journal of Geoscience》2017,110(3):741-751
Fossil anguine lizard specimens from several Turkish localities are described in this paper. The material comes from ten different localities, spanning a large geographic area consisting of both parts of the European Turkey and Anatolia, and ranging in age from the Oligocene to the Late Miocene. In certain cases, the generic determination was possible and, accordingly, members of Ophisaurus and Anguis were identified and described in detail. The specimens of Anguis, found in different, Middle and Late Miocene localities from Anatolia, represent two of only a few fossil occurrences of this taxon. Moreover, the material reported herein represents the oldest occurrences of anguine lizards, not only from Turkey, but from southeastern Europe and the Eastern Mediterranean basin as a whole. These rare records provide important information about the dispersal routes of anguines from Europe to Asia and significantly enhance our understanding of their biogeography. 相似文献
15.
SPI-based evaluation of drought events in Xinjiang, China 总被引：5，自引：1，他引：4
Daily precipitation data for 1957?C2009 from 53 stations in the Xinjiang, China, are analyzed, based on the Standardized Precipitation Index (SPI) with the aim to investigate spatio-temporal patterns of droughts. The Mann?CKendall trend test is used to detect the trends in the SPI values of monthly drought series, drought severity and drought duration. The frequencies of moderate, severe and extreme droughts are higher in the North Xinjiang, while mild droughts occur more often in the South Xinjiang. A decreasing frequency of droughts in the North Xinjiang is found in winter, but a drying tendency is detected in the western parts of the North Xinjiang during spring, summer and autumn, which may be harmful for agriculture. The South Xinjiang seems to be getting wetter in summer, while the south parts of the South Xinjiang seem to be getting drier in spring. The middle of the East Xinjiang is identified to be in a slightly dry tendency. The drought severity is decreasing and drought duration is getting shorter in the North Xinjiang, while both of them increase in the southern parts of the South Xinjiang. In addition, droughts in the middle parts of the East Xinjiang are intensifying. 相似文献
16.
Spatio-temporal Distribution of Three Kinds of Flash Droughts over Agricultural Land in China from 1983 to 2015 总被引：1，自引：0，他引：1
At present, flash drought occurs globally and regionally and causes a lot of socio-economic loss in a very short time. Therefore, flash drought has been regarded as one of the hottest issues in drought research. However, flash drought monitoring, prediction and decision-making have encountered a lot of challenges due to its multiple driven factors and complex spatio-temporal process. Aiming at this problem, this paper focused on the agricultural land in China, and analyzed the spatio-temporal distribution of three kinds of flash droughts (i.e., precipitation-deficit, high-temperature, and composite flash droughts) from 1983 to 2015. We studied the occurrences, duration, spatial distribution, temporal distribution, and trend of all three kinds of flash droughts. Our results demonstrated that, the occurrences of flash drought agricultural land in China increased year by year, among which high-temperature flash drought increased dramatically; duration of flash droughts had different trends, but the variations were relatively smooth; Northeast China was identified as a vulnerable area of flash drought, indicating more flash drought events and longer duration; flash droughts in China were found to concentrate in spring (high-temperature drought) and summer seasons (precipitation-deficit drought). This study is helpful for building new flash drought monitoring method and system, and it is also valuable for flash drought preparedness on regional scale. 相似文献
17.
从干旱定义与识别、点干旱频率分析和区域干旱频率分析3个方面系统阐述了干旱频率分析研究进展和存在问题,归纳了适用于干旱频率分析的干旱定义,干旱识别存在的主要问题以及区域干旱频率分析研究的3种途径。提出综合利用研究区域水文气象特性、干旱成因、旱情、旱灾,并结合前期的大气环流条件等信息来描述和识别干旱,重点开展对干旱特征变量的理论分布、干旱事件重现期公式和经验频率公式等基本理论的研究,关注区域干旱频率分析,注重对径流、土壤水、地下水和供水系统的干旱特性分析。 相似文献
18.
在干旱事件不确定性和枯期径流变异性的双重影响下,水文干旱特征时序非一致性问题为其联合分布模拟带来困难。基于东江干流测站日径流过程数据,采用游程理论提取水文干旱事件,并结合干旱特征均值变化、时序一致性分析及边缘分布模拟,以确定干旱事件融合及剔除评判标准的合理取值。基于Rosenblatt变换Cramer-von Mises检验统计量拟合方法,构建水文干旱特征两变量联合分布Copula模型,并根据同频法设计两变量组合值。通过对比枯期径流变点分隔子序列干旱特征,分析变化环境下东江流域水文干旱特征及缺水响应。结果表明:水文干旱事件融合和剔除的评判标准值分别取0.1和0.3比较合理。干旱特征两变量之间具有较高的正相关性,但不同时间系列不同变量之间的联合分布及边缘分布最优模型并不一致。流域水库尤其是新丰江水库的径流调节作用,对于缓解东江中下游水文干旱效果明显,超阈联合重现期为2年的设计干旱持续时间、总缺水量和最大日缺水量分别减少了63%~71%、71%~84%和30%~47%,但如果要满足东江河道内最小管理流量目标,其依然分别达到了12~18 d、6 114万~9 030万m3和715.0万~929.0万m3。 相似文献
19.
Amrit Kumar Pandey Rajendra P. Mishra Surendra K. Daradur Mihail 《Natural Hazards》2018,92(2):1199-1210
The frequency and severity of occurrence of meteorological droughts in different climatic regions depend on regional climatic factors. This study has made an effort to explore the relationship of range of annual temperature variation at a given place with the frequency of occurrence of drought and the maximum magnitude of seasonal rainfall deficit (i.e., severity). The seasonal rainfall refers to sum of monsoon season (rainy season) rainfall in India. The monthly precipitation data of 113 years (1901–2013) for 256 stations in different parts of India have been used to estimate the return period of meteorological drought at different stations. The daily normal values of observed maximum and minimum temperatures from 40 years of records have been utilized to estimate range of temperature variation (θR) during the year at each stations. In various parts of India, the θR ranges from 10 °C in humid regions to 40 °C in arid regions. The various climatic regions have been experiencing maximum deficiency of annual rainfall ranging from 30% (humid) to 90% (arid). The results reveal that places exhibiting θR values between 40 to 30 °C face more frequent droughts with average frequency of once in 3 to once in 6 years. The occurrence of extreme and severe drought events is more frequent in the regions with higher values of θR compare to that in lesser values of θR. The regions with θR values between 30 to 25 °C mostly face severe and moderate events having the average drought return period of 6–9 years, and the occurrence of extreme droughts in these regions is rare. Furthermore, regions with θR?<?20 °C face moderate droughts only with an average return period of 14 years. This study divulges that the average return period and magnitude of deficiency of drought events have notable relationship with the range of temperature variation during the year at a given place.
相似文献20.
2009年秋季到2010年初春,遵义市出现了特大干旱,对农业、林业、人畜饮水、水利电力等方面造成严重的危害和巨大的损失。详细分析干旱期间的气象要素,从秋季9月到初春3月的总降水量不足常年同期平均值的一半,并与历史上的秋冬干旱年份进行了比较,发现本次干旱期间遵义市大部分地方降水量等多项气象要素突破历史最少记录,因此认为2... 相似文献