Previous maximum flows on many streams and rivers were exceeded during the flood of 1993 in the upper Mississippi River Basin. Not only were peak discharges exceeded at many streamflow-gaging stations, but also flood volumes were significantly higher than previous maximums. Rainfall amounts that were greater than 127 cm (50 in.) were recorded in parts of Kansas, Missouri, and Iowa from April 1 through September 30, 1993. As a result of the excessive rainfall, 53 of the 60 stations discussed had flow volumes greater than twice the mean flow volume for April through September. The Mississippi River at St. Louis, Missouri, remained above flood stage for 144 days from April 1 to September 30, 1993, compared with 81 days during the spring and summer flood of 1973. Of the 60 stations, 24 recorded new maximum 3-day flood volumes, and 47 recorded new maximum 120-day flood volumes. This indicates that the flooding of 1993 is significant with respect to its long duration and magnitude of flow. The same aspect is indicated in the frequency analysis of the 1993 flood. During the 1993 flood, the 100-year 3-day flows were exceeded at 22 stations, and the 100-year 120-day flows were exceeded at 43 stations.
