Practical considerations in modeling earth dam overtopping

Authors: Temple, Darrel; Hanson, Gregory; Hunt, Sherry

Submitted to: International Hydro-Science & Engineering International Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/1/2004
Publication Date: 7/1/2004
Citation: Temple, D.M., Hanson, G.J., Hunt, S. 2004. Practical considerations in modeling earth dam overtopping. In: Advances in Hydro-Science and -Engineering, Vol. VI. Proc. of the 6th International Conference on Hydro-Science and -Engineering. Brisbane, Australia. 8 pp. CD-ROM.

Interpretive Summary: Significant numbers of watershed flood control dams in the United States are approaching the end of their planned service life. These structures provide flood control, recreation, fish habitat, water supply and other beneficial uses. Aging, combined with development around these dams and reservoirs, increases the possibility and consequences of failure of these dams. Therefore, there is a need for improved technology to evaluate the potential for failure if a dam is overtopped during extreme rainfall and flood events. Research performed in the outdoor laboratory is providing the necessary technical information to allow development of computational tools for engineers and others to use in making decisions related to design, rehabilitation, and maintenance of these vegetated earth dams. Use of these tools will allow optimum use of resources to keep these dams and reservoirs safe and functioning as intended.

Technical Abstract: Significant numbers of watershed flood control dams in the United States are approaching the end of their planned service life. As the sediment pools fill and sediment encroaches on the flood storage, the potential for overtopping is increased. Changes in the watershed upstream may also increase overtopping potential, and encroachment on the floodplain downstream may magnify the consequences of a dam failure due to overtopping. These factors have resulted in an increased need for improved mathematical and computer models describing the breach process for embankment dams subjected to overtopping during extreme flood flows. Observation of overtopped embankments in the field and in the outdoor laboratory indicate that it is possible to approach the development of a mathematical model through examination of the component processes. This approach allows simplification of the mathematical description of the complex interaction of the flow with the eroding boundary. Advances in understanding the erosion processes associated with vegetated earth spillways form a point of beginning for component modeling of the breach process. Work has been initiated to obtain the additional data required to expand the spillway erosion concepts for application to development of a physically based embankment breach model. This report discusses the overall breach process and the progress being made toward development of a computational tool for engineering application.