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关于水文同频率地区组成法中相应洪量频率的探讨

2018-11-13黄一昕梁忠民胡义明李彬权王军

南水北调与水利科技 2018年3期

黄一昕 梁忠民 胡义明 李彬权 王军

摘要:水文中往往需要研究水文变量在空间上的分配规律,同频率地区组成法是目前解决该问题的一个重要方法,但其中仍有一些理论问题悬而未解。以“上下同频、区间相应”的组成方案为例,区间相应量的频率C与“同频”中设计频率P之间的大小关系,无法判断,目前尚无理论证明。因此,对正态分布和PⅢ分布,分别通过理论推导和统计试验途径,明确了C与P之间关系。对设计洪水问题,根据“上下同频、区间相应”求得的区间相应洪量,其频率C将大于设计频率P;对径流或枯水设计问题而言,区间径流量的频率C将小于设计保证率P。研究结果从理论上进一步明晰了同频率地区组成法中相应量的频率问题。

关键词:同频率地区组成法;正态分布;PⅢ型分布;设计频率;设计保证率

中图分类号:P333.6文献标志码:A文章编号:16721683(2018)03018905

Discussion on the corresponding flood frequency in the Hydrological Equivalent

Frequency Regional Composition method

HUANG Yixin,LIANG Zhongmin,HU Yiming,LI Binquan,WANG Jun

(College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China)

Abstract:The spatial distribution rules of hydrological variables are often studied in hydrology.The Equivalent Frequency Regional Composition (EFRC) method is an important approach to solving this problem at present.However,there are still some theoretical issues that remain unsolved.Take as an example the composition scheme of "same design frequencies at upstream and downstream, with corresponding value at the interval",we cannot determine which is larger between the frequency of the interval area (C) and the design flood frequency (P) at both upstream and downstream due to a lack of theoretical proof.In this study,we investigated the relationships between C and P for the normal and Pearson type III (PE3) distributions by means of theoretical derivation and Monte Carlo (MC) experiment.Results showed that C is larger than P for the design flood problem, while for the design problem of runoff or low flow, P is larger than C.Therefore,this study has clarified in theory the design frequency of corresponding value at the interval for the EFRC method.

Key words:equivalent frequency regional composition method;normal distribution;Pearson type III distribution;design frequency;design guarantee rate

設计洪水分析计算是为水利及涉水工程提供合理的水文设计值[14],当涉及到多个站点(断面)的分析计算时,需要处理设计断面以上各部分设计洪水地区组成的问题。传统的设计洪水地区组成方法主要包括地区组成法、频率组合法和随机模拟法[1],其中,地区组成法是现行设计洪水地区组成计算中最为常用的方法。地区组成法研究的是当设计断面发生设计标准洪水时,上游及其区间洪水的地区组成情况。为了在各种可能出现的洪水地区组成中,选择一种特定的组成作为设计地区组成,使计算成果规范化且偏于安全,目前常采用同频率地区组成法,即“上下同频、区间相应”,或者“区间下游同频、上游相应”[58]。……

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