岩溶地区设计洪水计算方法探讨

Discussion on calculation method of design flood in karst area

岩溶地区特别是伏流暗河区集水面积比重较大的流域,直接按全流域计算设计洪水,将使得设计成果偏大。针对这一情况,本文提出了岩溶地区设计洪水计算方法的处理和修正,并以鄂西南湾潭河流域为例,将明流区、伏流暗河区分开计算设计洪水,然后叠加成为岩溶地区洪水设计。研究结果表明,经岩溶洞室滞洪调蓄后,伏流暗河区的出流量与天然情况有所不同,在达到一定量级后其增率和变幅逐渐减小,当这部分流量所占比重较大时,与明流区洪水一样采用上端无限的线型是不甚相符的,本文提出的明流区、伏流暗河区分开计算设计洪水的方法可有效避免这一问题,为岩溶地区洪水设计的计算提供了一种有效途径。

The flood design results are larger while the whole basin as the calculation range in karst area, especially the basin with a big proportion of underground river flow concentration area. Taking the Wantanhe river basin in southwest of Hubei province, the paper provides the correction treatment method for flood design in karst area. The method calculates the design flood of the surface runoff area and the underground river area respectively, and then gets a superposition design result of the whole region. The results show the runoff generation discharge is different from the discharge under natural conditions after the dissolved cavern storage. The increase rate and variation amplitude is decreases gradually after getting a special order. The line style is different from the one of the runoff generation with an infinite upper tail. This method could avoid the questions reasonably.