复合式出流口滞洪坝之滞洪特性研究

山坡地滞洪设施中，不同出流口形式之滞洪坝，有不同的滞洪效应及滞洪容积。为剖析滞洪设施中受制入流历线作用下其滞洪容积变化，以无因次滞洪理论为基础，讨论滞洪池内其滞洪容积对应时间变化情形，进而推求该滞洪池之最小滞洪容积；同时采用下方宽底梯形断面，上方衔接一窄口矩形之复合式出流口滞洪坝进行室内渠槽试验；并制造不同形态之入流历线，针对不同梯形底宽布置下之滞洪效应及出流口流量公式分析探讨。证明复合式出流口于低流量时，因宽底梯形断面可将水快速排出，增加池内净空间；当流量大时可增加其滞洪能力。故本复合式出流口设计，于入流条件相同下，其所需之最小滞洪容积较矩形窄口式为小。

Study on Flood Detention Characteristics of Detention Dam with Compound Outlet

Different designs of detention dam outlets constitute different detention efficiency and volume on hillslope.The volume change of retarding basins were obtained by using the non-dimensional detention theory,with the known flow hydrograph in the detention facility. The minimum detention volume of retarding basin can be calculated based on the results of change of detention volume.The compound outlet with inferior trapezoid and upper rectangle was tested in a laboratory flume.The detention efficiency and dischange formula with different trapezoid widths at bottom would be analysed by using different inflow hydrograph in the flume.Based on the limited test results,it is proved that trapezoid section results greater de-tention volume under low inflow,and the detention efficiency is improved under high inflow. Therefore,the detention volume of compound outlets would be smaller than the rectangular outlets under the same inflow hydrograph.