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Title: Comparison of two process based earthen dam failure computation models

Author
item Tejral, Ronald
item Hanson, Gregory
item TEMPLE, DARREL - Retired ARS Employee

Submitted to: State Dam Safety Officials Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2009
Publication Date: 9/29/2009
Citation: Tejral, R.D., Hanson, G.J., Temple, D.M. 2009. Comparison of two process based earthen dam failure computation models. In: Dam Safety 2009. Proceedings of the Association of State Dam Safety Officials Annual Conference, Sept. 27-Oct. 1, 2009, Hollywood, FL (CDROM).

Interpretive Summary: Dams present a risk to property and life due to their potential to fail. Our ability to predict the rate of failure and resulting flood hydrograph is crucial to evaluating the risk to life and property. Discussed are two process-based computational breach tools and their underlying principles. These are the National Weather Service BREACH model developed by Danny Fread and the simplified breach analysis model, SIMBA, being developed by the USDA-ARS. Underlying assumptions and equations used to describe the erosion process are significantly different. Comparisons are made of dams for which flood waters were above the top of dam. These comparisons were based on the results of experiments conducted by USDA-ARS and a series of hypothetical embankments. The study identified strengths and weaknesses of the computational models. It also provided additional evaluation and validation of SIMBA, the model being developed by USDA-ARS.

Technical Abstract: Dams are an important part of this nation's infrastructure providing flood control, water supply, irrigation, hydropower, navigation, and recreation. Despite their many beneficial uses, dams present a risk to property and life due to their potential to fail. They are also a part of the nation's aging infrastructure, and without proper maintenance, repair, rehabilitation, and upgrading the risk of failure and associated damage is increased. Our ability to predict the rate of failure and resulting flood hydrograph is crucial to evaluating the risk to life and property. Today there are several tools for predicting the magnitude of dam failure including methods based on physical processes of erosion during overtopping. Discussed are two process-based computational breach tools and their underlying principles. These are the National Weather Service BREACH model developed by Danny Fread and the simplified breach analysis model, SIMBA, being developed by the USDA-ARS. Underlying assumptions and equations used to describe the erosion process are significantly different. NWS BREACH is a sediment transport driven model whereas SIMBA is primarily a headcut migration model. Comparisons are made of overtopped dams, based on physical model tests conducted by USDA-ARS and a series of simulations.