Maybe Build Walls?

I have a question, Why does the Red River flood every year? Why don't they bulid brick walls throughout the rest of the year around the rivers and whatnot to stop the flooding, maybe they can't stop the water everywhere but they could at least stop some places from flooding and save money instead of having to put up sand bags EVERY year. I think that would be a smart thing to do, bulid brick walls, just make them thick enough that you could put sand bags on top if needed. Right after the flooding the city should start putting up sandbags for next year if they cannot afford the build walls, That way they might not have cars driving pretty much underwater (Just like the picture above), buildings and homes wrecked and lives lost.

-Nikita-