What will stop water from going up, around?

Two things worry me about the flood protection topic.

One is how high should the walls be? Common sense tells you that when the next big floodwaters come and the water is restricted to the new, narrow channel created by the walls, that the massive amount of incoming water will not simply move through the channel quickly, but will back up on itself, and climb higher. A similar volume of water to 2008 could climb over the planned wall, unless the walls are built 40 feet high!

Two is when I look at aerial pictures of the Cedar Rapids flood, I realize that next time, with the walls, as the water builds up and backs up, it will not back up to the cities upstream; it will simply go around the ends of the walls. What's to stop that from happening? Look at the pictures! Convince me that I'm wrong about these two things.

Pete Looney

Marion