U.S. Geological Survey: Science for a Changing World - USGS visual identity mark and link to main Web site at http://www.usgs.gov/

SUMMARY AND CONCLUSIONS
Flow records from the Mississippi River and Rio Grande reflect major known droughts and wet periods and extreme flood events of the last 100 years. For example, the Dust Bowl of the 1930's is a prominent feature in the flow records from the Mississippi Basin, reflecting the widespread and persistent effects of the drought. The large flood of 1993 is obvious in the flow record of the Mississippi River but is absent from the Rio Grande record, reflecting the regional distribution of that flood event. Similarly, the high flow in 1941 in the Rio Grande record is not represented in the Mississippi River flow because the extreme wet conditions of 1941 were restricted to the Southwestern United States.
Comparison of ENSO records with historical flow records indicates that the large drainage area of the Mississippi River complicates any ENSO signal that may be present in the flow record of any individual tributary river. The flow record from Vicksburg is not statistically related to individual ENSO events. The flow record from the Rio Grande, however, does include an ENSO signal that is consistent with the link between ENSO and climate in the Southwestern United States (Diaz and Kiladis, 1992; Stahle and Cleaveland, 1993).
In summary, variations in flow of the Mississippi River and Rio Grande into the Gulf of Mexico reflect major droughts and wet intervals and extreme flood events. Several studies (for example, Kennett and others, 1985; Brown and others, 1999) indicate that changes in surface-water salinity and sediment input associated with major flood events are recorded in sediments accumulating on the shelf and slope of the Gulf of Mexico. Detailed study of sediments accumulated at high rates off the coasts of Texas and Louisiana have the potential to provide long and well-dated continuous records of major hydrologic events on the adjacent continent.
U.S. Geological Survey, U.S. Department of the Interior
This page is https://pubs.usgs.gov/bulletin/b2187/summary.html
Contact: Harry Dowsett (hdowsett@usgs.gov)
Last modified 09.26.01 (krw)