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The 1993 Mississippi flood peaked on different dates from St. Paul to Thebes
Six Mississippi River gauges in the USGS flood report reached their peak flows between 26 June and 7 August 1993. St. Louis reached 1.08 million cubic feet per second on 1 August, a day after the Missouri River peak at Hermann.
Sources checked
- Mississippi River at St. Paul, MN104,000 ft³/s
- Mississippi River at Clinton, IA245,000 ft³/s
- Mississippi River at Keokuk, IA435,000 ft³/s
- Mississippi River at St. Louis, MO1,080,000 ft³/s
- Mississippi River at Chester, IL950,000 ft³/s
- Mississippi River at Thebes, IL975,000 ft³/s
Natural Earth land outlines and dashed land boundaries.
Pins show peak discharge. Straight segments connect the gauges in upstream-to-downstream order. The table records dates and five tributary gauges.
The flood was a sequence of peaks
The St. Paul gauge peaked on 26 June. Clinton followed on 5 July and Keokuk on 10 July. St. Louis peaked on 1 August and Thebes on 7 August. The dates describe local maxima at each station during a prolonged event. Source 1
Tributary flow changed the downstream picture
The USGS describes a second and larger discharge peak at St. Louis after peak Missouri River flow reached Hermann on 31 July. Gauge drainage areas give a sense of the changing scale. St. Paul drains 36,800 square miles, and St. Louis drains about 697,000. Source 1
Stage and discharge describe different measurements
Discharge is the volume of water passing a cross-section per second. Stage is a water-surface reading relative to the local gauge datum. Chester’s stage was 49.59 feet and St. Louis reached 49.58 feet, while their peak flows were 950,000 and 1,080,000 cubic feet per second. Source 1 Source 2
The peak was one day in a long flood
The NWS record counts 147 days above the 30-foot St. Louis flood stage across April through October 1993. Its archive records one day below flood stage during July, August and September. A peak-flow comparison and a time-above-threshold comparison describe different aspects of the disruption. Source 3