The existing flood control dam at Canton, Oklahoma, was being upgraded with an auxiliary spillway to enable it to safely pass the new Probable Maximum Flood (PMF). The auxiliary spillway weir will be equipped with Fusegates, which will tip individually at predetermined water elevations to release flood water as needed. The service and auxiliary spillways together must be able to discharge a PMF of 17,000m3/s without overtopping the dam. To facilitate this, a hybrid numerical and physical hydraulic model study of the spillway system was conducted at Alden Research Laboratory.
First, a numerical model study was carried out for various approach geometry designs to investigate approach flow patterns, resulting water surface elevations throughout the reservoir and spillways, as well as flow rate splits between the two spillways. Based on the CFD results, a favorable design was selected, constructed and tested in a large-scale 1:54 scale topographic physical model. The advantage of this hybrid, integrated numerical and physical modeling approach is that each model can be used where it has its strengths: Numerous modifications of the approach channel geometry were made in a cost-effective way in the numerical model. The large-scale physical model was then used to validate the numerical results, for final modifications that brought the maximum reservoir elevation at PMF to within acceptable levels, to obtain the spillway rating curves and for Fusegate-specific tests.