Why did extensive flooding occur upstream of St. Louis during the 1993 Mississippi River flood?
A)Widespread urbanization in the upper portion of the basin increased runoff to a great degree.
B)Floodwalls protecting St. Louis caused a bottleneck in the river's flow.
C)The St. Louis floodwall failed, flooding St. Louis and the area upstream.
D)An intense thunderstorm dropped several inches of rain on the area in only a few hours.

Question

Quizplus · Accepted Answer

The floodwalls in St. Louis caused a bottleneck in the flow of the river, backing up water and causing extensive flooding upstream. This was a major contributing factor to the severity of the 1993 Mississippi River flood.

Why Did Extensive Flooding Occur Upstream of St