Humans caused the Midwest flooding.

"It's humans, not biblical downpours, that have raised the Mississippi River water level 10 to 15 feet higher in the past 100 years. "We've made the river flow through a much narrower channel, and we've put these piles of rocks in the river which slow down the flow," says Kusky. "The only place for the water to go is to rise upward and increase the height of the floods."
...Even before the recent deluge, scientists sounded the alarm. Back in March, weeks before the floods occurred, Criss, Pinter and professor Timothy Kusky of St. Louis University sent a letter to the commander for the St. Louis district of the Army Corps of Engineers, critiquing the new structures that the agency puts into the Mississippi and Missouri to make it easier for large barges to navigate the area. "These structures are loaded cannons pointing at St. Louis and East St. Louis, waiting to go off during the next large flood," wrote the scientists.
Now that the river can't naturally spread out on its flood plain or meander, the extra water under flooding conditions has nowhere to go. "If floodwaters can't spread out as they would in a natural flood plain environment, they can only go up," explains Criss." LINK