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N. Vivekanandan 《Environmental Earth Sciences》2018,77(5):201
Estimation of rainfall and temperature for a desired return period is a prerequisite for planning, design and operation of various hydraulic structures and for evaluation of technical and engineering appraisal of large infrastructure projects. This can be computed through Extreme Value Analysis (EVA) by fitting probability distributions to the annual series of 1-day maximum rainfall, maximum and minimum temperature. This paper details the study on adoption of Extreme Value Type-1, Extreme Value Type-2, 2-parameter Log Normal and Log Pearson Type-3 (LP3) probability distributions in EVA of rainfall and temperature for Hissar. Based on the applicability, standard parameter estimation procedures such as method of moments, maximum likelihood method (MLM) and order statistics approach are used for determination of parameters of distributions. The adequacy on fitting of probability distributions used in EVA of rainfall and temperature is evaluated by goodness-of-fit (GoF) tests, viz. Anderson–Darling and Kolmogorov–Smirnov and diagnostic test using D-index. The GoF and diagnostic tests results suggest the LP3 (MLM) is better suited amongst four probability distributions adopted in EVA of rainfall and temperature for Hissar. 相似文献
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Flood frequency analysis of river swat using Log Pearson type 3, Generalized Extreme Value,Normal, and Gumbel Max distribution methods 总被引：1，自引：0，他引：1
Muhammad Farooq Muhammad Shafique Muhammad Shahzad Khattak 《Arabian Journal of Geosciences》2018,11(9):216
In Pakistan, floods are among the most devastating and recurring natural hazards. Flood hazard assessment requires flood event magnitude and probability of occurrence. Flood frequency analysis is the most common technique used for the at-site estimation of flood recurrence magnitude. This paper evaluates four most commonly used distribution methods, i.e., Generalized Extreme Value (GEV), Log Pearson 3 (LP3), Gumbel Max, and Normal for the flood frequency and estimation of flood recurrence. Different hydrological stations data namely Khwazakhela, Chakdarra, Panjkora, and Munda Headwork located at Swat river was taken from Provincial Irrigation Department, Khyber Pakhtunkhwa. The analysis is done for 5-, 10-, 25-, 50-, and 100-year return periods by using annual maximum discharge data from 1980 to 2016 (37 yr). Three goodness-of-fit tests were applied to the fitted distributions, i.e., Kolmogorov–Smirnov, Anderson–Darling, and Chi-squared at 5% significance level. Results indicate that LP3 and GEV were ranked top two distributions at all locations while Gumbel Max and Normal were the least fitted having rank 3 and 4, respectively. Based on the goodness-of-fit ranking, LP3 was selected for the estimation of flood magnitude and return periods at Khwazakhela. Designed hydrographs based on probabilistic approach and flood 2010 hydrograph are presented for flood simulation. 相似文献
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Nibedita Guru Ramakar Jha 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(2):135-145
Flood frequency analysis is a pre-requisite for setting up and safeguarding of many hydraulic structures, such as dams, barrages, check-dams, culverts and urban drainage systems. In the flood frequency analysis, partial duration series (PDS) may be considered when dealing with values exceeding certain limits causing floods. In fact, the PDS is capable of getting more information about extreme events than the annual maximum series (AMS). Additionally, an assumption that, the magnitude of the extreme events of a PDS is best described by a generalized Pareto (GP) distribution. The present work investigates the at-site flood frequency analysis to find the average number of peaks (λ) for modelling the PDS on the basis of the PDS/GP assumption and variability in the GP parameters coupled with the quantile estimation with an increase in the value of average number of peaks (λ) each year in the Mahanadi river system, Odisha, India. Also, to verify the PDS/GP assumption we tested seven different frequency distributions (Exponential, Gumbel, logistics, generalized extreme value (GEV), Lognormal (LN), generalized logistics (GL) and Pearson Type 3). Extensive daily discharge data collected from 23 gauging sites were used for the analysis. The results indicate precision and stability of GP distribution parameters for λ?=?4 for almost all the discharge sites. The peak flood estimated for various return periods in the Mahanadi river system using GP distribution is endowed with high correlation statistics for this λ value. 相似文献
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关于长江中游洪灾问题的思考 总被引：2，自引：0，他引：2
中国是一个水灾频发的国家 ,长江中游历来就是重灾区。 1998年的长江洪水是 1954年以来最大的一次全流域性洪水 ,高水位持续时间长 ,洪水量大 ,洪水遭遇情况恶劣是这次长江汛期的突出特点 ,由此造成的损失十分严重。导致长江中游洪灾的原因是众多的 ,其中气候异常是最直接的影响因素 ,但过度围湖垦殖与江湖关系失调亦是洪涝灾害日趋严重的一个重要原因。由于自然演变和人类活动的共同作用 ,长江中游河湖环境越来越不利于超额洪水的排泄。江汉湖群、洞庭湖和鄱阳湖面积缩小 ,容积减少 ,对河流水量的调蓄作用大大降低。同时荆江已演变为典型的弯曲河道 ,成为防洪的重点地段。荆江大堤的修建隔断了江湖联系 ,改变了中游河湖关系。所有这些因素都使得中游洪灾日益加重。为了实现区域可持续发展 ,迫切需要建立一套完善的抗洪减灾防御体系。 相似文献
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流域区间的治涝方案以及排涝设施的规模都与区间暴雨和外江洪水位的遭遇息息相关,因此需要研究区间暴雨与外江洪水位遭遇的风险规律.采用copula函数建立区间暴雨和外江洪水位的联合分布,用联合概率密度来描述两者遭遇的机率,提出了以遭遇为设计组合的排涝风险率和重现期的分析方法.实例研究表明,copula函数能够较好地模拟广东省阳山县区间暴雨与外江洪水位的联合分布;联合概率密度曲线表现为明显的正偏态分布,对于不超过10年一遇的暴雨,遭遇同频率的外江水位的机率最大;但对10年一遇以上的暴雨,最大遭遇机率的外江水位的重现期低于暴雨重现期;对任一排涝重现期,则有成反相关的区间最大暴雨和外江洪水位重现期的多种组合方案,且任一组合方案的暴雨重现期都大于排涝重现期. 相似文献
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分析了长江下游感潮河段大洪水和特大洪水高水位形成的水文因素,揭示了年最高水位今后一段时期内可能的变化趋势。主要结论是:该河段大洪水和特大洪水高水位的形成原因十分复杂,本世纪以来每次大洪水和特大洪水高水位的形成几乎都有其主要原因;该河段大洪水特大洪水高水位出现的频次有增加趋势;自1975年以来,年最高水位的均值呈明显的升高趋势,其主要原因是人类活动对防洪产生的负面影响,海平面上升也有一定的影响。 相似文献
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现行分期设计洪水模式估算的分期设计洪水值均小于或等于年最大设计值,达不到规定的防洪标准。采用Gumbel-Hougaard Copula函数描述两个分期的分期最大洪水之间的相关性结构,并构造边缘分布为P-Ⅲ分布的分期最大洪水联合分布,建立分期最大洪水与年最大洪水的关系式,讨论分期设计洪水频率与防洪标准应满足的关系,探讨能够满足防洪标准的新的分期设计洪水模式。应用示例表明,新模式主汛期设计值相对年最大设计值小幅度增加,而非主汛期设计值则小于年最大设计值,既满足不降低防洪标准的要求又能够起到优化设计洪水的作用,为分期设计洪水研究提供了一条新的思路。 相似文献
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采用25 m分辨率的DEM并收集多年洪水位、潮位数据,以保证源数据的精度和可靠性.结合研究区地貌特征和水系分布,基于ArcGIS的空间分析工具采用种子蔓延法进行了有源淹没分析计算,得到淹没区范围和水深分布图.结果表明：淹没区主要分布在水库和河流下游的冲洪积平原和海积平原,淹没面积共318.08 km2,占全区陆域面积的18.6%.洪水淹没深度为0~7.6 m.以水库为种子点的淹没区域较大,淹没水深自种子点到海岸线逐渐增大;以河流为种子点的淹没区域呈带状分布,淹没水深自河流中线向两侧逐渐减小. 相似文献
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渭河咸阳段全新世古洪水事件光释光测年研究 总被引：3，自引：1，他引：2
古洪水水文学研究是全球气候变化研究的前沿课题,确定古洪水事件的年代是古洪水研究的重要内容之一。对渭河流域进行深入的野外考察,在中游咸阳段阶地发现全新世黄土-古土壤层里夹有古洪水滞流沉积层,表明该地层记录了古洪水事件发生的信息。在该剖面采集光释光样品,分离提取40~63 μm石英颗粒成分,应用单片再生剂量法（SAR）进行红外后蓝光(Post-IR OSL)释光测量,获得了9个OSL年龄值。结果表明由古洪水滞流沉积层记录的特大古洪水事件发生在3 200~2 800 a B.P.之间。结合沉积样品系列的磁化率和粒度成分等气候替代性指标分析,揭示了在全新世中期向晚期转折过渡时期,渭河流域处于气候向干旱化发展的转型期,气候变化剧烈,大气系统不稳定,降水变率增大等,是导致特大洪水多发的主要原因。这也是渭河流域气候水文系统对于全球性气候恶化响应的结果。 相似文献
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近年来长江中下游来沙量持续减少，河道面临长距离、长历时的冲淤调整，河道蓄泄关系发生变化，对防洪造成影响。在长江中下游河道冲淤及其蓄泄能力变化预测成果的基础上，对比计算了现状和未来河道蓄泄能力条件下，遇1954年洪水，长江上游水库防洪调度和中下游地区超额洪量的变化情况。结果表明，未来随着长江中下游河道进一步冲刷，河道槽蓄容积增加，相同防洪控制水位下的河道安全泄量增大，三峡水库在进行防洪调度时可下泄流量增大，总拦蓄洪量减小，长江中下游地区总超额洪量减小，但超额洪量在地区分布上存在从上游向下游转移的情况。 相似文献
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L. N. Plummer E. Busenberg S. Drenkard P. Schlosser B. Ekwurzel R. Weppernig J. B. McConnell R. L. Michel 《Applied Geochemistry》1998,13(8):1017-1043
Tritium/helium-3 (3H/3He) and chlorofluorocarbon (CFCs, CFC–11, CFC–12, CFC–113) data are used to date the young fraction in groundwater mixtures from a karstic limestone aquifer near Valdosta, Georgia, where regional paleowater in the Upper Floridan aquifer receives recharge from two young sources—the flow of Withlacoochee River water through sinkholes in the river bed, and leakage of infiltration water through post-Eocene semi-confining beds above the Upper Floridan aquifer. In dating the young fraction of mixtures using CFCs, it is necessary to reconstruct the CFC concentration that was in the young fraction prior to mixing. The 3H/3He age is independent of the extent of dilution with older (3H-free and 3Hetrit-free) water. The groundwater mixtures are designated as Type-1 for mixtures of regional paleowater and regional infiltration water and Type-2 for mixtures containing more than approximately 4% of river water. The fractions of regional paleowater, regional infiltration water, and Withlacoochee River water in the groundwater mixtures were determined from Cl− and δ18O data for water from the Upper Floridan aquifer at Valdosta, Georgia.The chlorofluorocarbons CFC–11 and CFC–113 are removed by microbial degradation and/or sorption processes in most anaerobic (Type-2) groundwater at Valdosta, but are present in some aerobic Type-1 water. CFC–12 persists in both SO4-reducing and methanogenic water. The very low detection limits for CFCs (approximately 0.3 pg kg−1) permitted CFC–11 and CFC–12 dating of the fraction of regional infiltration water in Type-1 mixtures, and CFC-12 dating of the river-water fraction in Type-2 mixtures. Overall, approximately 50% of the 85 water samples obtained from the Upper Floridan aquifer have CFC–12-based ages of the young fraction that are consistent with the 3H concentration of the groundwater. Because of uncertainties associated with very low 3H and 3He content in dilute mixtures, 3H/3He dating is limited to the river-water fraction in Type-2 mixtures containing more than about 10% river water. Of the 41 water samples measured for 3H/3He dating, dilution of 3H and low 3He concentration limited 3H/3He dating to 16 mixtures in which 3H/3He ages are defined with errors ranging from ±2 to ±7.5 a (1 σ). After correction for dilution with (assumed) CFC-free regional infiltration water and regional paleowater in the Upper Floridan aquifer, adjusted CFC–12 ages agree with 3H/3He ages within 5 a or less in 7 of the 9 co-dated Type-2 mixtures.Tritium data and dating based on both CFC–11 and CFC–12 in Type-1 mixtures indicate that travel times of infiltration water through the overlying Post-Eocene semi-confining beds exceed 35 a. The CFC and 3H/3He dating indicate that the river fraction in most groundwater entered the groundwater reservoir in the past 20 to 30 a. Few domestic and municipal supply wells sampled intercept water younger than 5 a. Calculated velocities of river water in the Upper Floridan aquifer downgradient of the sinkhole area range from 0.4 to 8.2 m/d. Radiocarbon data indicate that ages of the regional paleowater are on the 10 000-a time scale. An average lag time of approximately 10 to 25 a is determined for discharge of groundwater from the surficial and intermediate aquifers above the Upper Floridan aquifer to the Withlacoochee River. 相似文献
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近年来长江中下游来沙量持续减少,河道面临长距离、长历时的冲淤调整,河道蓄泄关系发生变化,对防洪造成影响。在长江中下游河道冲淤及其蓄泄能力变化预测成果的基础上,对比计算了现状和未来河道蓄泄能力条件下,遇1954年洪水,长江上游水库防洪调度和中下游地区超额洪量的变化情况。结果表明,未来随着长江中下游河道进一步冲刷,河道槽蓄容积增加,相同防洪控制水位下的河道安全泄量增大,三峡水库在进行防洪调度时可下泄流量增大,总拦蓄洪量减小,长江中下游地区总超额洪量减小,但超额洪量在地区分布上存在从上游向下游转移的情况。 相似文献
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长江中游武汉-九江河段河道卡口及其阻洪可能效应探讨 总被引：8，自引：0，他引：8
探讨了长江中游武汉九江河段河道卡口的地质地貌方面特征,并通过对历史水文数据的分析研究了中游河道卡口对洪水的阻碍作用。并以田家镇卡口为典型案例,利用研究河段的水文资料,分析了中游河道卡口对洪水排泄的阻碍作用;如若实施田家镇扩卡,将对中游的防洪是有利的,而且会大大减轻中游特别是武汉的防洪压力,但有可能对下游河势的稳定、河床演变等造成影响,并可能造成其它环境影响,尚需进一步研究。当前全球变暖、水循环加剧、长江中游降水增多,长江中下游将面临更大防洪压力,通过长江中下游扩卡增泄,以适应当前全球变暖的影响。 相似文献
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张菊红 《物探化探计算技术》2013,(6):696-703
松辽盆地南部伏龙泉气田下白垩统泉头组一段为主力产气层段,但从未进行过系统的沉积微相研究。从岩芯分析入手,结合区域地质资料、测录井资料,利用岩石相与测并相转换技术对工区内泉一段的沉积微相进行了刻画,提出伏龙泉气田下白垩统泉头组一段属于辫状河沉积体系,共识别出心滩、河道滞留、泛滥平原和决口扇四种沉积微相,建立了辫状河垂向沉积层序,并对其沉积微相平面展布特征进行了研究。泉一段为辫状河沉积,心滩发育,河道边部发育大面积的泛滥平原,心滩砂体呈透镜状,平行于水流方向在河道内分布,垂向上交错叠置,横向上大规模连片,分布稳定并具有较好连通性。 相似文献
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裸露型岩溶区因其特殊的地质环境条件而具有独特的岩溶水资源形成和分布规律,其地下水资源十分丰富,但由于时空分布极不均匀,开发利用程度低,导致脆弱的岩溶环境所形成岩溶干旱及岩溶洪涝等生态环境问题突出。本文通过对凯德场地下河系统的水文地质特征、地下水开发利用条件进行分析,提出了因地制宜的地下水开发利用方案,为改善流域农村饮水不安全局面及生态环境提供有效途径,实现环境、经济、社会的协调发展。 相似文献
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汾河下游柴庄以下河段由于受人为和处在然等多种因素影响,河道发生持续淤积,过水能力大幅度降低,使河道行洪特点发生很大变化,正常洪水预报方法失效。 相似文献