[Red River Landing, Louisiana]

It’s not all that easy, actually, to rank the severity of the 20th century’s great Mississippi floods.  One reason is that Mississippi River flooding is often primarily on the upper Mississippi (1993) or the lower Mississippi (1973, 1983), which makes like-to-like comparison difficult.  Another is that there are so many different ways to measure the severity of a flood, even at a single geographical point.  Take the Red River Landing Gauge, the Army Corps’ monitoring apparatus just below the Old River Control.

The Corps uses the Gauge to measure flood severity by three conditions: stage (flood height in feet above “gauge zero”, which is the elevation of the river’s surface at average low flow), volume (of flow), and “days in flood” (the period of time for which the river’s stage has been above the elevation determined to be “flood stage”; at Red River Landing, this is 48 feet).

By stage the worst flood measured in the 20th century at Red River Landing was 1997, which topped out at 61.3 feet, followed by 1927 at 60.9 feet.  (Just a few days ago — 26 May, if I read the Corps’ website properly — the Gauge recorded 62.13 feet, which exceeds any measurement taken in the 20th century.  At the time of this writing, 2 June, it is currently at 60.9 feet, and predicted to continue gradually decreasing tomorrow.)  By volume, it was easily 1927, which at 1799 Kefs dwarfed 4th-placed 1997’s 1480 Kefs.  The increased channelization of the river and the effects of implemented flood control measures are seen in the discrepancy between these numbers — because the horizontal space available to the flooding river diminished so much between 1927 and 1997, and the river was encouraged to take faster paths to the delta, it took a significantly smaller flow of floodwater to produce a slightly higher flood stage.  This is anthropogenically accelerated flooding.  Finally, by days in flood, 1927 is again the clearly most severe flood, with 135 days, and trailed by 1983’s 115 days.  No other floods lasted more than a 100 days.