Breaching Parameters for Earth and Rockfill Dams

Dam risk analysis is at the heart of dam failure prevention and mitigation. In order to assess dam risk, it is essential to conduct a quantitative analysis of the process of a dam breach, which can be described by such parameters as breach geometry, breaching duration, and peak outflow rate. The main objective of this paper is to develop robust empirical formulas with physical meaning for predicting dam breaching parameters based on past dam failure data. A database of 182 earth and rockfill dam failure cases has been compiled; among these cases nearly one-half are for large dams higher than 15 m. A multiparameter nonlinear regression model is recommended to develop empirical relationships between five breaching parameters (breach depth, breach top width, average breach width, peak outflow rate, and failure time) and five selected dam and reservoir control variables (dam height, reservoir shape coefficient, dam type, failure mode, and dam erodibility). The relative importance of each control variable is evaluated. The dam erodibility is found to be the most important factor, influencing all five breaching parameters. The reservoir shape coefficient and the failure mode also play an important role in the prediction models. Two case studies are presented to show the application of the empirical models developed in this paper.

[1]  G. W. Kirkpatrick,et al.  Evaluation guidelines for spillway adequacy , 1977 .

[2]  Robin Fell,et al.  Investigation of Rate of Erosion of Soils in Embankment Dams , 2004 .

[3]  Y. Xu,et al.  Analysis of earth dam failures: A database approach , 2009 .

[4]  Thomas C. MacDonald,et al.  Breaching Charateristics of Dam Failures , 1984 .

[5]  J. E. Costa.  Floods from dam failures , 1985 .

[6]  Vijay P. Singh,et al.  Dam Breach Modeling Technology , 1996 .

[7]  Somchai Wongwises,et al.  Embankment dam breach and its outflow characteristics , 2004 .

[8]  Rune Storesund,et al.  Levee Erosion by Overtopping in New Orleans during the Katrina Hurricane , 2008 .

[9]  Árni Snorrason,et al.  Sensitivity of outflow peaks and flood stages to the selection of dam breach parameters and simulation models , 1984 .

[10]  Martin W. McCann.  National Performance of Dams Program , 1997 .

[11]  Tony L. Wahl,et al.  Uncertainty of predictions of embankment dam breach parameters , 2004 .

[12]  David C. Ralston,et al.  Mechanics of Embankment Erosion During Overflow , 1987 .

[13]  Jean-Louis Briaud,et al.  Case Histories in Soil and Rock Erosion: Woodrow Wilson Bridge, Brazos River Meander, Normandy Cliffs, and New Orleans Levees , 2008 .

[14]  David C. Froehlich,et al.  Peak Outflow from Breached Embankment Dam , 1989 .

[15]  David C. Froehlich,et al.  Embankment Dam Breach Parameters Revisited , 1995 .

[16]  R. L. Dewey,et al.  Prediction of Embankment Dam Breaching for Hazard Assessment , 1993 .

[17]  Chi Fai Wan,et al.  Time for Development of Internal Erosion and Piping in Embankment Dams , 2003 .