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A physically-based method for predicting peak discharge of floods caused by failure of natural and constructed earthen dams

January 1, 1997

We analyse a simple, physically-based model of breach formation in natural and constructed earthen dams to elucidate the principal factors controlling the flood hydrograph at the breach. Formation of the breach, which is assumed trapezoidal in cross-section, is parameterized by the mean rate of downcutting, k, the value of which is constrained by observations. A dimensionless formulation of the model leads to the prediction that the breach hydrograph depends upon lake shape, the ratio r of breach width to depth, the side slope ?? of the breach, and the parameter ?? = (V/ D3)(k/???gD), where V = lake volume, D = lake depth, and g is the acceleration due to gravity. Calculations show that peak discharge Qp depends weakly on lake shape r and ??, but strongly on ??, which is the product of a dimensionless lake volume and a dimensionless erosion rate. Qp(??) takes asymptotically distinct forms depending on whether ?? < < 1 or ?? > > 1. Theoretical predictions agree well with data from dam failures for which k could be reasonably estimated. The analysis provides a rapid and in many cases graphical way to estimate plausible values of Qp at the breach.

Publication Year 1997
Title A physically-based method for predicting peak discharge of floods caused by failure of natural and constructed earthen dams
Authors J. S. Walder
Publication Type Article
Publication Subtype Journal Article
Series Title IAHS-AISH Publication
Index ID 70019435
Record Source USGS Publications Warehouse
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