河道汇流口水力特性对鱼类栖息地的影响

Effect of Hydraulic Characteristics of Confluent Channel on Physical Habitat for Fish Communities

利用河道水流增量法(IFIM)研究了交汇河口汇流比、汇流口下游弗劳德数及汇流口下游宽深比这3个主要水力控制因素对鲤科鱼类及平鳍鳅科鱼类栖息地的影响.结果表明:在交汇河口,水力条件的变化对鲤科鱼类及平鳍鳅科鱼类适宜栖息地分布影响不大;随着汇流比增大,加权可用面积(WUA)逐渐减小;随着汇流口下游弗劳德数增大,WUA迅速减小;随着汇流口下游宽深比增大,WUA逐渐增大,且增幅很小.IFIM可以给出鱼类适宜栖息地面积与各水力控制因素之间的定量关系,可为河流管理与决策提供支持.

The effects of three controlling hydraulic factors, including the discharge ratio, the Froude number of flow at lower river and the ratio of width to depth of channel at lower river, on physical habitat of fish communities were investigated by use of the instream flow incremental methodology （IFIM）. The results show that with the change of hydraulic conditions, the range of physical habitat for cyprinoid and Hillstream loaches remains steady relatively; with the discharge ratio increasing, the weighted usable area （WUA） decreases gradually; with the Froude number of flow at lower river increasing, the WUA decreases sharply; and with the ratio of width to depth of channel at lower river increasing, the WUA increases gradually. IFIM can identify the quantitative relationship between WUA and each hydraulic factor and provide support for river management and decision.