What causes flooding in the Mississippi River drainage basin?
The Mississippi River has the third largest drainage basin in the world. It drains 41% of the 48 contiguous states of the United States and covers more than 1,245,000 square miles, including all or part of 31 states. If large amounts of rain fall over an extended period of time within this great drainage basin, a flood may occur. Such floods extend over long periods of time and affect the Mississippi River, tributary streams, and the surrounding land. Why does the Yazoo Backwater Area Flood? As waters rise on the Mississippi River, it impedes the natural gravity flow on the Yazoo River, forcing the Yazoo River water to back up into the lower Delta region. This backwater flooding is not a sudden surge of water, but a slow moving flood that can remain above flood stage for several months at a time. Under normal conditions, the Steele Bayou’s structure gates are open, allowing for interior creeks and rivers to drain using gravitational flow. However, if their flow is impeded by higher Mis
