No.
1. It's not below sea level, so it will drain. That's a big factor.
2. They CAN evacuate - they have jobs and cars, for the most park.
Re 1 - The amount of drain tile in the surrounding area will play apart in how the city will drain. Its not quite as simple as "it will drain"
Re 2 - From what I've heard/read bridges were closed and I-80 is shut down. The notice to get out of town was given after the bridge was closed.
Cedar rapids is a complete mess, the downtown is flooded to at least the top of the first floor (I've heard that its 32' above the 100 year event).