CS30B - Concurrent Session 30B: Comparison of Modern-Day Flood Modeling Techniques (3-D versus 2-D, with 1-D on the wane)

Looking back through history, we cannot deny the crucial role that water has played for humans in developing civilization. To meet this demand, many dams were built for uses such as irrigation, potable water, flood control, hydropower, recreation, and more. Along with the benefits of controlled water comes the increased danger of potential structural failure, or multiple failures, and corresponding downstream human impacts.
In recent decades, and with the constant increase of technology, more and more attention has been given to the analysis of existing, as well as soon to be designed dams with respect to their ability to pass huge flows, Probable Maximum Floods (PMFs), without failures.

The ever increasing advancement of computer technology has enabled us to rely more on numerical (less costly) models, and less on physical (more costly) models with the latter being used mainly to check the numerical model results and to calibrate software.

The process of selecting numerical models (1-D, 2-D, or 3-D) and computer software is very critical and depends on many factors that are defined in detail in this paper.

If a computerized model can be viewed as a "black box" that has been approved for use by an authoritative organization (for example FEMA), then the accuracy of input data into that "black box" is essential for receiving accurate and precise outputs. In this paper, great care has been given to the consideration of necessary input data, technology of the calculations, and selection of appropriate input values.

Depending on complexity, computer model calculations may take anywhere from several minutes, up to a few months. The best way to present results obtained from a computer simulation are video animations.

The animations, as the primary product of 2-D and 3-D models, represent a high-level view of the modeling results with a temporal dimension that 1-D models lack. This tool can help us visualize what to expect when this adverse event occurs. The animation can be played on any device, such as a laptop or a tablet, as a video (movie) file, so that not only drainage engineering experts can understand the design results, but also any person without engineering knowledge can easily see the results during the design storm event. In animations, the different water depths, velocities, and dynamic pressures can be presented with assorted colors, so that the progression of water depths, velocities, and dynamic pressures over time can be seen.