Yes. Oklahoma has real flood risk from flash flooding, river flooding, creek overflow, stormwater drainage, and heavy rain.
Oklahoma flood risk is not limited to one city or one river. Oklahoma City, Tulsa, Norman, Broken Arrow, Edmond, Lawton, Moore, Stillwater, and smaller communities can all have different risk profiles based on drainage, elevation, development, nearby creeks, and river systems.
Flood Nerd take: Oklahoma is not just a tornado state. It is also a flash-flood and drainage-risk state. That matters because water does not care whether the lender required coverage.