Adding a specific height to flood elevations?

[huesmann]

I’m working on a floodplain model where the client wants to show the 100-year boundary, and also the boundaries of “100-year plus 2 ft” and “100-year plus 3 ft.”

I’m able to use RAS Mapper to show the 100-year, but I’m at a loss as to how to proceed to show the 100+2 and 100+3. Is there a way to generate profiles of 100+2 and 100+3 that I could use RAS Mapper to create boundaries for?

[Anonymous]

The best I can think of:

After you create your 100-year model and run it, create a new plan and steady flow file. From the steady flow editor, go to options, Set Internal Changes in WS and EG. Add multiple RS locations and add every cross section using Known WS. In the value column enter the water surface you want.

To make things easier, from one of the output editors, you could copy the 100-year results to Excel and add “2” or “3” and then copy that result back into the Value column for the known WS.

[huesmann]

Someone at my firm had the idea to just change the global datum by 2 or 3 feet and re-run the model, which seems to have worked.

[Author]

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