Table 2 summarizes the rainfall depths used for the design storm events in the ICPR modeling and compares them to the cumulative rainfall for Hurricane Irma and Hurricane Ian, which were used for calibration events.
Table 2 – Rainfall Depths
| Storm Event | ICPR Model (24-hr) (inches) | Actual Cumulative (inches) |
|---|---|---|
| 50-year | 8.86 | -- |
| 100-year | 10.20 | -- |
| 500-year | 15.0 | -- |
| Irma | -- | 10.0-10.4 (6 Days) |
| Ian | -- | 17.5-18.6 (2 days) |
For the flood data box evaluation, the overtopping storm event elevation was based on the lowest point along the SR 72 profile using the project Digital Elevation Model (DEM). Overtopping between basins is included in the modeling in the form of overland weirs and is also included in the flood data box. Modeling will be used during design to demonstrate no increase in offsite stages confirming no impacts to offsite properties. Modeled pipe invert elevations, lengths, and sizes are from survey.
If the 500-year discharge did not result in overtopping of SR 72 then the data was entered in the Flood Data Box as the Greatest Flood. If the 500-year discharge did result in overtopping the roadway, then the lowest discharge resulting in overtopping was determined and the frequency of the storm event was calculated using the best fit between a power or linear trend line for the modeled discharges verse frequency probability. This result was recorded as the Basin Overtopping Flood within the Flood Data Box.
Page | 7