Date of Award:

1994

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Civil and Environmental Engineering

Advisor/Chair:

David S. Bowles

Abstract

Incremental damage assessment is a tool used to assess the justification for expensive modifications of inadequate dams. The input data to incremental damage assessment are the output from the breach analysis and flood routing. For this reason, flood routing should be conducted carefully. Distorted results from the flood routing technique or unstable modeling of the problem will distort the results of an incremental damage assessment, because an error in the estimated incremental stage will cause a certain error in the estimated incremental damages.

The objectives of this study were (1) to perform a comprehensive survey of the available dam break flood-routing techniques, (2) to evaluate the performance of commonly used flood-routing techniques for predicting failure and no-failure stage, incremental stage, average velocities, and travel times, and (3) to develop a set of recommendations upon which future applications of dam break models can be based.

Flood-routing techniques that are evaluated cover dynamic routing as contained in DAMBRK, and kinematic, Muskingum-Cunge, and normal depth storage routing as contained in the Hydrological Engineering Center (HEC 1). These techniques were evaluated against the more accurate two-dimensional flood-routing technique contained in the diffusion hydrodynamic model (DHM). Results and errors from different techniques for different downstream conditions were calculated and conclusions were drawn. The effect of the errors on the incremental stage and the errors in the incremental stage were estimated. Overall, the performance of one-dimensional techniques in predicting peak stages, and assessing a two-feet criterion showed that DAMBRK did best, and normal depth storage and outflow did worst. This overall ranking matches the degree of simplification in representing the true flood-routing situation. However, in some circumstances DAMBRK performed worst, and normal depth storage and outflow outperformed either the Muskingum-Cunge or kinematic techniques. Thus, it is important to understand the specific performance characteristics of all the methods when selecting one for a flood-routing application.

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