Effect of Water Surface Elevation Study in Dam Break Modeling

Abstract

This paper concerns the modeling of the dam break and highlights the consequences to the downstream river reaches, from the hydraulics point of view of quantitatively assessing the flow

rate and the wave profile resulted along the downstream river reaches temporally and spatially, and presents an analysis of changing initial water surface elevation in dam (WSELD). The model computes the reservoir outflow hydrograph resulting from changing the initial water surface elevation, which includes effects of submergence from downstream tail water depths and corrections for approach velocities. Also, the effects of storage depletion and upstream inflows on the computed outflow hydrograph are accounted for through storage routing within the reservoir show the effect of the output discharge due to change of initial water surface elevation.

A case study is offered to illustrate the application of several changes in water surface level methods on Teton dam failure. Dam break modeling implemented the hydraulic routing (dynamic hydraulic routing in this case) through two approaches. The first approach is by developing a flood routing methodology and implemented in the FORTRAN code “MDMBRK?”, compiling and running the code to produce the required results, the second involves the application of well- established and documented software “FLDWAV” developed and used by the US Army Corps of Engineers in the United State and all over the world. Both approaches have been calibrated and applied to a well-documented case study of Teton Dam failure, Idaho-USA. As conclusion the first approach requires less computational time, more flexible and simpler to be used for simulating the model. The results, for both approaches, have shown a very good agreement between the measured and simulated hydrographs. Sensitivity analysis has been demonstrated further by varying the changing of initial water surface elevation in a Dam (WSELD). The problem solving approach developed in this research is very important for dam’s owners, operating authorities and emergencies and disaster management authorities.