长江上游与洞庭湖洪水遭遇风险分析

Floods encountering risk analysis for upper Yangtze River and Dongting Lake

为进一步揭示长江上游与洞庭湖洪水遭遇规律,本文以宜昌站和城陵矶站1951—2016年实测日均流量资料为基础,建立了两站年最大洪水洪峰、15日洪量、洪水发生时间及间隔时间的边缘分布函数,进而构建了基于Archimedean Copula函数的洪水发生时间和量级(包括洪峰和过程)的联合分布函数,解析了长江上游与洞庭湖洪水的遭遇风险。其中针对长江上游与洞庭湖洪水洪峰之间,以及它们的洪峰及其发生时间之间均存在相关性的特点,提出了一种通过建立两站洪峰及其间隔时间的联合分布来研究洪峰遭遇风险的方法。最后分析了三峡水利枢纽的运用对长江上游与洞庭湖洪水遭遇风险产生的影响。研究成果可为三峡水库优化调度和长江中下游的防洪减灾提供理论依据。

To better understand the encountering patternof floods from the upper Yangtze River and Dongting Lake,this paper presents a fitting analysis of the probability distributions of annual maximum(AM)flood peaks,15-day flood volumes,flood occurrence dates,and flood occurrence intervals for the two hydrological stations of Yichang and Chenglingji,based on their daily discharge records of the period 1951-2016.We use the Archimedean Copula functions to examine the encountering risk characteristics of the occurrence dates and discharges(including peak discharges and discharge time variations)of the stations’floods.To analyze flood peak encountering risks,we formulate a joint distribution probability of the flood peaks and flood intervals of the two stations through considering their flood peak correlations and the correlations between each station’s flood peaks and occurrence dates.Finally,influence of the Three Gorges reservoir on the two stations’floods encountering risks is analyzed to help the optimal operation of the reservoir and the flood prevention and disaster reduction in the middle and lower Yangtze River.