共查询到19条相似文献，搜索用时 109 毫秒
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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
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干旱研究中的均值生成函数模型 总被引：3，自引：1，他引：2
干旱规律研究是水旱灾害对策研究的一个重要内容。较好地模拟历史上干旱发生及其演变规律,对于客观预测未来干旱发生情况和有关部门作出准确相应的决策具有十分重要的意义。本文以分析一维时间序列为基础,介绍了均值生成函数这一概念,提出了应用正交化筛选建立模型的思路,并且经数学推导建立了均值生成函数模型。最后将模型应用于山西省榆林地区、陕西省关中地区的月农业干旱指标序列的模拟与预测。研究结果表明,均值生成函数模 相似文献
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概念性水文模型在出山径流预报中的应用 总被引：37，自引：6，他引：37
根据HBV水文模型的基本原理，建立了西北干旱区内陆河出山径流概念性水文模型。该模型反映了我国西部山区流域的径流形成特征，将山区流域划分为高山冰雪冻土带和山区植被带两个基本海拔景观带来对山区径流的形成和汇流过程进行模拟计算，以常规气象站的月气温和降水量为模型的初始输入，模拟计算月出山径流量。应用该模型对河西走廊黑河祁连山北坡的山区流域水量平衡进行了模拟计算，并对年径流和逐月分配进行了预报。结果表明，从枯水年到丰水年，降水量、蒸发量、径流量和径流系数均增加，而冰川融水和积雪融水对出山径流的补给比重则减少，这表明了冰雪融水对径流的具有调节作用。黑河山区流域径流系数远比干旱内流区的平均值大，但要小于全国的平均径流系数。所提出的内陆河山区流域出山径流的模拟和预报模型对年径流量和月分配的预报具有较好的精度，可用于黑河以及其他西北干旱区内陆河出山径流的预报，为内陆河流域中下游的水资源分配和开发利用提供依据。 相似文献
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选用标准化降水指数作为气象干旱指标,通过引入多标度分形理论,运用乘法级联模型,以吉林西部6个气象站点1957年1月-2010年10月的月降水量数据为基础,对吉林西部气象干旱的多标度性质进行分析。研究结果表明,吉林西部气象干旱的发生在时间尺度上均具有多标度分形特征,但在不同站点多标度分形的强度不同,表现出一定的空间差异性。其强弱次序为：长岭<通榆<白城<前郭<扶余<乾安。 相似文献
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利用西北五省区137个测站的1961-2009年逐月降水量资料计算标准化降水指数(SPI), 统计了逐月、春末夏初、初夏、夏季及秋季的干旱、重旱、特旱的频率及面积率, 分析其时空变化特征.结果表明: 新疆北部、青海的中部及甘肃河西是西北地区干旱频率较高的区域, 干旱频率在15个月以上, 新疆南部除个别月份干旱发生频率较高外, 总体干旱发生频率较低;干旱发生区域随月份有由南到北、由西向东变化的趋势;除新疆、青海、及甘肃个别区域重旱频率超过5月外, 其他区域基本上都在5月以下;新疆南部重旱频率仍然较低;夏季发生范围高于其他季节;新疆北部、甘肃河西是特旱的高发区. 不同等级的月及季节干旱面积率其逐年变化具有相似的特征, 西北干旱面积率的变化总体上可以分为3个阶段: 1961-1980年干旱面积率比较高, 平均在35%左右;1981-1990年为转折期, 干旱面积率下降到15%左右;而1991-2009年为稳定期, 干旱面积率变化不大.全球气候变暖导致西北地区降水量、冰川融水量、河川径流量增加和湖泊水位上升、面积扩大, 是1987年以来干旱面积率下降的原因. 相似文献
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非平稳条件下北京市最大月降水量频率特征分析 总被引：1，自引：1，他引：0
为探究气候变化下极端降水的频率变化特征,基于北京市22个雨量站实测月降水量数据,以时间为协变量构建平稳和非平稳GEV模型,对北京市最大月降水量序列(极值降水序列)进行模拟和频率分析,并采用Bootstrap方法对频率分析结果的不确定性进行评价。结果表明:所有极值降水序列的最优概率分布模型均为非平稳GEV模型,该模型能够抓住序列随时间呈显著下降趋势的变化特征;由非平稳GEV模型估算得到的极值降水重现水平随时间呈减少趋势,这意味着未来极值降水导致洪涝灾害的风险在降低,但导致干旱的风险将增加;随着重现期的增加,极值降水重现水平估计值的不确定性也随之增大。 相似文献
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中国东北三省1960—2005年地表干燥度变化趋势 总被引：6，自引：0，他引：6
为研究气候变化对东北三省地表干湿状况的影响,利用该区1960—2005年72个气象站的观测资料,采用Penman Monteith模型计算了各站的潜在蒸散量,由潜在蒸散量和降水量之比构建干燥度指数,并采用Kriging法进行空间插值以分析其区域特征。结果表明,该区地表干湿状况具有明显的时空变化特征。1960—1979年间,由于降水减少和潜在蒸散增加,地表干燥度指数呈增加趋势,水汽压差增大是潜在蒸散增加的主要原因;1980—2005年间,大部分地区地表干旱状况有所减缓,其中以黑龙江省和吉林东部尤为明显。降水增加和潜在蒸散减少是地表干旱状况趋缓的主要原因,风速降低和净辐射减小导致潜在蒸散减少。总体而言,气候变化并未加剧东北三省的干旱化。 相似文献
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Under the current condition of climate change, droughts and floods occur more frequently, and events in which flooding occurs after a prolonged drought or a drought occurs after an extreme flood may have a more severe impact on natural systems and human lives. This challenges the traditional approach wherein droughts and floods are considered separately, which may largely underestimate the risk of the disasters. In our study, the sudden alternation of droughts and flood events (ADFEs) between adjacent seasons is studied using the multivariate L-moments theory and the bivariate copula functions in the Huai River Basin (HRB) of China with monthly streamflow data at 32 hydrological stations from 1956 to 2012. The dry and wet conditions are characterized by the standardized streamflow index (SSI) at a 3-month time scale. The results show that: (1) The summer streamflow makes the largest contribution to the annual streamflow, followed by the autumn streamflow and spring streamflow. (2) The entire study area can be divided into five homogeneous sub-regions using the multivariate regional homogeneity test. The generalized logistic distribution (GLO) and log-normal distribution (LN3) are acceptable to be the optimal marginal distributions under most conditions, and the Frank copula is more appropriate for spring-summer and summer-autumn SSI series. Continuous flood events dominate at most sites both in spring-summer and summer-autumn (with an average frequency of 13.78% and 17.06%, respectively), while continuous drought events come second (with an average frequency of 11.27% and 13.79%, respectively). Moreover, seasonal ADFEs most probably occurred near the mainstream of HRB, and drought and flood events are more likely to occur in summer-autumn than in spring-summer. 相似文献
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Drought risk assessment using remote sensing and GIS techniques 总被引：1，自引：0，他引：1
Abdel-Aziz Belal Hassan R. El-Ramady Elsayed S. Mohamed Ahmed M. Saleh 《Arabian Journal of Geosciences》2014,7(1):35-53
Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors. 相似文献
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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
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Deng-Hua Yan Dong-Mei Han Gang Wang Yong Yuan Yong Hu Hong-yang Fang 《Natural Hazards》2014,73(2):849-858
Based on the daily precipitation data of 38 weather stations in the Huai River Basin from 1961 to 2010, this study used SPI index, P-III curve to determine the flood/drought years, under what situations for droughts and floods easily happen, and to analyze the evolution law of flood and drought during inter-annual and intra-annual based on the characteristic of monthly precipitation. The results showed that: (1) annual rainfall of the Huai River Basin presented decreasing trend, maximum rainfall appeared from June to August, and multi-year average precipitation increased gradually from north to south; (2) the variation of monthly precipitation during flood years was more severe than other typical years, and precipitation in drought years showed nearly 50 % decline compared with normal years; (3) high rainfall of flood years was mainly caused by the increase in rainfall in flood season, and the strategy of flood control and drought relief was “short-term flood prevention and long-term drought relief”; (4) while precipitation of most months in drought year was reduced, the relevant strategies “annual basin-wide of long-term drought prevention” should be carried out; (5) combination events of floods and droughts occurred frequently. Persistent drought dominated in spring and summer while droughts and floods that happened alternately were mainly in summer and autumn. 相似文献
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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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气象干旱发展到一定程度可以传递为水文干旱。以潘家口水库流域1961—2010年逐月平均降水数据和潘家口水库的入库径流序列为基础数据,分别计算了1、3、6、12个月时间尺度的标准化降水指数（SPI）和标准化径流指数（SRI）,以表征研究区域的气象干旱和水文干旱。基于条件分布模型,分析了不同时间尺度的气象干旱传递到未来的不同等级和不同的预测期（或滞后期）的水文干旱的概率。结果表明,当SPI时间尺度较短或预测期（滞后期）较短时,其对应的SRI水文干旱等级越倾向于维持与SPI相同的干旱等级;随着SPI时间尺度的增长或预测期（滞后期）延长,其对应的SRI水文干旱等级略低于气象干旱或恢复到正常状态。 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
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An Analysis of Spatial and Temporal Dimension of Drought Vulnerability in Turkey Using the Standardized Precipitation Index 总被引：3，自引：1，他引：2
Drought has become a recurrent phenomenon in Turkey in the last few decades. Significant drought conditions were observed during years of late 1980s and the trend continued in the late 1990s. The countrys agricultural sector and water resources have been under severe constraints from the recurrent droughts. In this study, spatial and temporal dimensions of meteorological droughts in Turkey have been investigated from vulnerability concept. The Standardized Precipitation Index (SPI) method was used to detail geographical variations in the drought vulnerability based on frequency and severity of drought events at multiple time steps. Critical (threshold) rainfall values were derived for each station at multiple-time steps in varying drought categories to determine least amount of rainfall required to avoid from drought initiation. The study found that drought vulnerability portrays a very diverse but consistent picture with varying time steps. At regional scale, south-eastern and eastern Anatolia are characterized with moderate droughts at shorter time steps, while the occurrence of severe droughts at shorter time steps is observed at non-coastal parts of the country. A similar picture was observed with very severe droughts. The critical (threshold) values exhibited rising numbers during the growing season at 3-month step in the South-eastern Anatolia, which might have significant consequences considering presence of large irrigation projects under-development in the region. In general, rainfall amounts required for non-drought conditions decrease from the coastal parts toward the interiors with increasing time steps. 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