Well since I live in a newer section, actually it has never flooded! This part must have been built in the 1930s and 40s. There's an even newer part more south and I think it continues to grow in that direction.
My late neighbor used to tell stories of when my avenue was the last one. Beyond that was virgen prairie; undeveloped natural habitat! And they would just play softball in the fields. Much that once was is lost. None now live who remember it.

Some parts of streets might get inundated now, like during a heavy storm in autumn or springtime. I don't count that as a good though because it drains quickly and the basement remains dry. This is nothing compared to the Rains in Mexico or the little bit of the typhoon season I witnessed in the Philippines.

The northern section of the neighborhood is probably so much older that I don't think they even have true basements. It's only, like you said, the original ground floor is the basement even though it's not underground. I don't know the exact number either, but the street over there is elevated maybe 4 meters
or more