Visualizing Levee Failures and Performance through 2-D Techniques
Co-authored by Hector Olmos, P.E., CFM
Freese and Nichols developed an Emergency Action Plan (EAP) for a Levee Improvement District in Fort Bend County, Texas. The purpose of the EAP is to outline the actions that need to be implemented before, during and after a breach of the levee. In order to better define the actions that need to take place after a breach of the levee, our team developed a hydraulic model of the levee-protected area, and multiple potential flooding sources from perimeter intrusion or direct rainfall utilizing InfoWorks ICM.
Rivers, creeks and canals were represented with one-dimensional (1-D) elements, while other areas with no clearly defined flow paths, including residential areas, were represented with a two-dimensional (2-D) mesh. The result is a seamless hydraulic model that better represents the interaction of the different flooding sources, drainage systems, and consequences of a levee breach.
Simulations included a system analysis of design events, historic flood scenarios, system response to various storms on different flooding sources, filling related to direct rainfall deposition, breaches at various locations in the levee system, and exterior level of protection from overtopping.
Results from each simulation provided detailed flow, depth, travel times and velocity data useful to understand available time to evacuate residents and allocate resources. The knowledge gained from these results was used to make informed judgments on the EAP based on consistently flooded areas, situational flooding and high ground good for staging a response.