By Eric W. Strom |
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streams all sang together for their homes that they had forsaken in the hills." --Lord Dunsany Mississippi receives an average of about 56 inches of rainfall annually--that's almost 127 billion gallons of freshwater every day. Streams flowing into the State provide more than 2 billion gallons of additional freshwater each day. Of this, about 79 billion gallons per day are lost to evaporation or is taken up by plants and transpired into the atmosphere. This leaves an average of about 50 billion gallons of freshwater each day to flow through the rivers and streams of Mississippi and ultimately discharge into the Gulf of Mexico. Most major rivers occupy a drainage basin of the same name, sometimes called a watershed, or catchment. These drainage basins are areas usually bounded by relative topographic highs, or drainage divides, within which all surface-water runoff generally is channeled into a single, main stream. Of course, drainage basins can be defined at many different scales--from the small creek that drains a few acres, to the Mississippi River that drains much of the interior of the United States. If we consider a scale on the order of a state, about ten major drainage basins can be defined for the State of Mississippi. Eight of the larger basins are discussed below--they are the Big Black, Coastal Streams, Mississippi, Pascagoula, Pearl, South Independent, Tombigbee, and the Yazoo drainage basins (see figure). The following discussion of the river basins was compiled from previous investigations conducted by the U.S. Geological Survey and the Mississippi Department of Environmental Quality. Information regarding land use was obtained from the Geographic Information Resource Analysis System (GIRAS) data base, and, in some instances, may have changed since the data were compiled due to inevitable changes in land use over time.
The Mississippi River The mighty Mississippi River is on a scale of its own. It is the largest river in the United States. The river basins described above have drainage areas on the order of thousands of square miles; in contrast, the drainage basin of the Mississippi River is well over 1 million square miles. The average flow for the Mississippi River at Vicksburg is 373 billion gallons of water per day! In times of flood, flow of more than three and a half times that amount has been recorded. For an example of how much water that really is, just 1 billion gallons are equal to a column of water whose base is equal to that of a football field and whose height is more than 4 times that of the 555 foot Washington Monument. Summary Mississippi is home to some of the most beautiful river basins in the world. Over 1,550 square miles of Mississippi are covered with streams, lakes, bays, and estuaries that are surrounded by more than 29,000 square miles of forests. Water quality of the streams is variable, but generally good. The rivers of Mississippi are used by recreationalists, sportsmen, industries, municipalities, agriculture, and wildlife. They are truly among the most valuable resources of Mississippi. |
Back to Water Resources in Mississippi Contact gepeters@usgs.gov Last modification September 10, 1998 |
