Dam break - Outburst flood propagation and transient hydraulics: A geosciences perspective
Dam break - Outburst flood propagation and transient hydraulics: A geosciences perspective
复制标题
溃坝 - 溃决洪水传播和瞬态水力学：地球科学的视角
DOI：
10.1016/j.jhydrol.2009.11.009
复制
发表时间：
2010
影响因子：
6.4
通讯作者：
Carrivick J
中科院分区：
文献类型：
--
作者：
Carrivick J
溃坝溃决洪水是在一个最初“干燥”的地形上传播的突然的、短暂的和高量级的水和沉积物排放。地质学家的实地观察和工程师的实验测量都产生了对突发洪水的理解，但这两种方法都没有令人满意地提供直接用于灾害管理的数据。本研究汇集了这两个文献组，并提供了新的实验数据，以测试假设的一系列外部控制的效果，所得的纵向流传播和瞬态水力学。这些外部控制形式的实验治疗，是：（一）作为大坝决口演变和初始过程线的替代品，（二）床粗糙度，和（iii）悬浮泥沙浓度的闸门提高的高度。这些控制水平和垂直流体运动，后者是控制曝气，床剪切应力和湍流强度的关键属性。试验结果表明，水平床面上的突洪具有三种纵向流态。首先，由于水库压力水平，即蓄水的深度，会有一个短暂的加速。其次，槽道流迅速收敛到惯性状态。第三种流态是粘性的，主要由河床摩擦力控制。流动深度在惯性状态下增加，然后在粘性状态下减小。本文中的实验表明，每个水力量的通道下的一点处的峰值的定时变化;最显著的是，峰值床剪切应力先于流速，流速先于峰值流深度。沿通道向下的距离处出现一个湍流点，这是加速流向减速流转变的表现。这些外部控制，以及它们对纵向和垂直运动的影响进行了统计分析，并得出定量关系来支持由此产生的概念模型。这个概念模型应作为一个平台，为未来的概率和过程为基础的洪水暴发建模。
Dam break outburst floods are sudden, short-lived and high-magnitude discharges of water and sediment propagating over an initially ‘dry’ terrain. Both field observations by geoscientists and experimental measurements by engineers have produced understanding of outburst floods but neither approach has satisfactorily supplied data that is directly of use to hazard managers. This study draws together those two literature groups and provides new experimental data to test hypotheses concerning the effect of a series of external controls on resultant longitudinal flow propagation and transitory hydraulics. These external controls form experimental treatments and are; (i) the height of the lock gate raise as a surrogate for dam breach evolution and initial hydrograph, (ii) bed roughness, and (iii) suspended sediment concentration. These control both horizontal and vertical fluid motion, the latter of which is a key property for controlling aeration, bed shear stress and turbulence intensity. The experimental treatments show that outburst floods on horizontal beds can be identified to possess three longitudinal flow regimes. Firstly, there is a short acceleration due to the reservoir pressure level; i.e. the depth of impounded water. Secondly, channel flow quickly converges to an inertial regime. The third flow regime is viscous and dominated by channel bed friction. Flow depth increases in the inertial regime, then decreases in the viscous regime. Experiments herein show that the timing of the peaks at-a-point down channel of each hydraulic quantity varies; most notably peak bed shear stress precedes flow velocity, which precedes peak flow depth. A point of inflexion occurs with distance down channel that is a manifestation of the transition from accelerating to decelerating flows. These external controls, and the effects of them on longitudinal and vertical motion are analysed statistically and quantitative relationships are derived to underpin the resultant conceptual model. This conceptual model should serve as a platform for future probabilistic and process-based modelling of outburst floods.