Partial area coverage distribution for flood frequency analysis in arid regions
Partial area coverage distribution for flood frequency analysis in arid regions
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干旱地区洪水频率分析的部分区域覆盖分布
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
J. Valdes
中科院分区：
文献类型：
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作者：
J. Marco;J. Valdes
高强度的对流暴雨是干旱地区发生大洪水的主要原因。对流风暴的规模有限，很少覆盖整个盆地。因此，洪水频率受暴雨覆盖率c的分布影响，暴雨覆盖率c是发生降雨的流域面积的分数。分析概率密度函数（pdf）估计的部分风暴覆盖作为一个功能的盆地面积sc和风暴半径rs的概率分布函数的覆盖面积分数c的条件pdf，给定的风暴半径f（c/rs），获得作为一个复合分布与有限的概率最大的覆盖和连续的密度较小的值。通过假设指数风暴半径边缘分布来去除条件性假设，以获得流域覆盖率pdf。该pdf是复合的，对于完整的集水区覆盖率P（c=1）具有离散概率，对于部分重叠具有连续函数。连续函数组合了Weibull pdf和c的线性函数。P（c=1）和f（c））均取决于平均集水区与风暴半径比χ。该分布解释了亚利桑那州核桃峡谷盆地的部分覆盖数据。然而，对于略小于完全覆盖，即对于0.9 < c < 1，观察到收缩。设计了一种概念性的事件分类和方法，以包括部分覆盖对洪水频率分布的影响。
Convective rainfalls of high intensity are largely responsible for most large floods occurring in arid regions. Convective storms are limited in size and rarely cover an entire basin. Therefore flood frequency is affected by the distribution of storm coverage c, which is the fraction of basin area upon which rainfall occurs. Analytical probability density function (pdf) estimates of partial storm coverage are presented as a function of basin area sc and the probability distribution function for storm radius rs Conditional pdfs for the covered area fraction c, given the storm radius f(c/rs), are obtained as a compound distribution with finite probability for maximum coverage and continuous density for smaller values. The conditionality assumption is removed by assuming an exponential storm radius marginal distribution to obtain the catchment coverage pdf. This pdf is compound, with discrete probability for complete catchment coverage P(c=1) and a continuous function for partial overlap. The continuous function combines a Weibull pdf and linear functions of c. Both P(c=1) and f(c)) depend on χ, the average catchment‐to‐storm radius ratio. The distribution explains the partial coverage data for the Walnut Gulch basin in Arizona. Departures were observed, however, for slightly less than complete coverage, namely, for 0.9 < c < 1. A conceptual event classification and a method were designed to include partial coverage effects on flood frequency distribution.