Abstract
Dams are constructed to benefit humans; however, dam-break disasters are unpredictable and inevitable leading to economic and human life losses. The sequential catastrophe of a dam break directly depends on its outflow hydrograph and the extent of population centers that are located downstream of an affected dam. The population density of the cities located in the vicinity of dams has increased in recent times and since a dam break hydrograph relies on many uncertainties and complexities in devising a dam-break outflow hydrograph, more researches for the accurate estimation of a dam-break flood propagation, extent and topography change becomes valuable; therefore, in this paper, the authors propose a novel and simplified dam-break outflow rate equation that is applicable for sudden-partial dam breaks. The proposed equation is extensively affected by a dam-break shape. Therefore, the inference of a dam-break shape on a dam-break outflow rate is investigated in the current study by executing hydraulic experiments in a long, dry bed, frictionless and rectangular water channel connected to a finite water tank to acquire a mean break-shape factor. The proposed equation is further validated by regenerating the Malpasset dam-break hydrograph and comparing it to the existing methods and also by installing it on an existing 2D hydro-morphodynamics flood simulation model. Finally, Amagase Dam’s (arch-reaction dam in Japan) break simulation is executed as a case study. The results of the simulations revealed that the greater the height of a dam-break section, the more devastating its flood consequences would be.
Highlights
As water is stored behind a dam, enormous potential energy is formed that in the case of a dam-break, devastating catastrophe may follow [1] especially, when densely populated cities are located downstream of a dam [2], in the last two decades, floods resulting from dam breaks are responsible for some of the most devastating man-made disasters
Qbi is the bed-load transport rate per unit width in the i direction; Cb is the bedload transport coefficient determined by verification simulations; the authors by performing many hydraulic experiments, developed useful diagrams to acquire the value of this coefficient, refer to Figures 3–5 [19]; θ s (t) is the Shields parameter in the i direction; θ sc is the critical Shields number, calculated by using the equation of van Rijn, [20]; ∆ is the relative density of the sand; g is the gravitational acceleration; D50 is the median diameter of the sediment
This study presented a novel, useful and simple approach for sudden partial dam break outflow rate
Summary
As water is stored behind a dam, enormous potential energy is formed that in the case of a dam-break, devastating catastrophe may follow [1] especially, when densely populated cities are located downstream of a dam [2], in the last two decades, floods resulting from dam breaks are responsible for some of the most devastating man-made disasters. In all studies predating [3], all researchers had assumed a total dam-break scenario which is not realistic and does not take into account the types of dams that can be partially breached Concerning this fact, Piloti et al [3] and Aureli et al [10] proposed methods to address sudden partial dam breaks. The storage-depth curves might either not be available or difficult to acquire for some existing dams To overcome this issue, the authors propose a new dam-break outflow rate equation that requires only the height of a dam for calculating a dam break outflow rate. The results suggest that, as the break section’s height increases, the inundation extent and initial flood velocity increase even if the break cross-sectional area tends to remain the same
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