西江流域梧州站干支流洪水组成及遭遇规律分析

Composition and Encountering Law of Floods at Wuzhou Station from Main Stream and Tributaries in Xijiang River Basin

为分析西江流域灾害性洪水的风险,采用水文学分析法从洪水组成、遭遇时间以及洪峰重现期等方面,重点分析了梧州站干支流洪水遭遇规律。研究表明:梧州15场洪水中红水河、柳江、郁江及桂江的日平均流量平均比重分别为32.31%、40.57%、13.19%及9.13%;其中西江干流洪水发生时间集中在6~8月,柳江洪水发生时间集中在6~7月,桂江洪水发生时间集中在5~7月,郁江洪水发生时间集中在7~9月;西江上游红水河与柳江洪水遭遇频繁,而郁江、桂江遭遇洪水量级较小,其中全流域洪水、红水河-柳江-桂江洪水、柳江-郁江-桂江洪水三种遭遇类型所构成的梧州大洪水重现期依次约为100年、50年、20年一遇,揭示了西江干支流洪水遭遇后致使梧州站洪水重现期显著增大。研究结果可为西江流域防洪减灾提供水文分析参考。

In order to analyze the risk of disastrous flood in the Xijiang River basin, this paper studied the encountering law of the floods at the Wuzhou Station from the main stream and tributaries in the aspects of flood composition, encounter time and flood peak return period based on the hydrological analysis method. The results show that the proportion of average daily flow for 15 floods at the Wuzhou Station from the rivers of Hongshui, Liujiang, Yujiang and Guijiang are 32.31%, 40.57%, 13.19% and 9.13%,respectively. The floods from the rivers of Xijiang, Liujiang, Guijiang and Yujiang mainly concentrate in June to August, June to July, May to July and July to September, respectively. The floods from the rivers of Hongshui and Liujiang encounter frequently,while the flood encounter flood grade of the Yujiang River and Guijiang River is small. The disastrous floods at the Wuzhou Station are composed of 3 kinds of flooding encounter types, which are the whole basin flood, Hongshui River-Liujiang River-Guijiang River flood, and Liujiang River-Yujiang River-Guijiang River flood. The recurrence periods of them are greater than 100,50 and 20 years in turn, as reveals the significant increase of flood recurrence period at Wuzhou station after the flood encounter of the main stream and tributaries in the Xijiang River. The results can provide hydrological analysis reference for flood control and disaster mitigation in the Xijiang River basin.