Here are two spacecraft images of the mighty Mississippi River, the largest river in the United States and the chief river of the largest river system in North America. The first images is from earlier this month (August, 2012) and shows a stretch of the river just south of Memphis, Tennessee. The other, which shows the same section of river, was acquired by NASA satellite almost exactly one year ago. Notice the contrast! In 2012, with ongoing severe drought in the central U.S., the Mississippi River is well below normal.
Landsat 7 captured the image above on August 8, 2012. Meanwhile, the image below was acquired nearly a year earlier.
Landsat 5 took the lower image on August 14, 2011. That spring, the Mississippi had swelled to historic high levels. It rose out of its banks and rolls across a wide flood plain, eating at flood barriers. But by August of 2011, the river was close to its normal level, according to NASA, which also said:
The Mississippi River is a major North American transit route, carrying goods to and from ports in New Orleans and Baton Rogue. The top image shows that low water levels have narrowed the river from a superhighway to a small road. The U.S. Army Corp of Engineers maintains a 9-foot shipping channel in the lower Mississippi and has dredges working around the clock to keep the channel clear. Not only are water levels low in 2012, but the floods of 2011 dropped a layer of sediment on the riverbed, reshaping previously open channels.
The reduced river flow in 2012 has translated into millions of dollars in extra shipping costs, as the loss of just one inch of draft means that a barge can carry 17 tons less than it otherwise would. The result is decreased shipping capacity.
Reduced water levels had one positive impact: The U.S. Army Corp of Engineers has been able to access and repair levees that were damaged in last year’s floods. The levees are the tan lines that surround the river in these images.
The Mississippi ranks as the fourth-longest and tenth-largest river in the world. The river either borders or cuts through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana. Many of these same states have been undergoing severe drought in 2012. See the image below.
Bottom line: With ongoing drought in the central U.S., the Mississippi River in 2012 is well below normal. This post contrasts two space images of the Mississippi – both from NASA Landsat satellites – one from August 2012 and the other from August 2011.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.