I recently ran across a number of stats presented by area scientists regarding the massive rains along the Upper Mississippi River last August. These rains produced unprecedented landslides in bluff country that resulted in seven deaths and several homes on both sides of the river sliding down onto the roads.
For more detailed stories, stats, photos, and reports from the August 07 flooding and landslides, see http://www.greatriver.com/natural/disaster/August07.htm
Official FLOOD STATS
15.1 inches of rain fell in Hokah, Minn., over a 24 hour period on August 19. The previous high was 10.84 inches set in 1972.
The Root River crested at 18 feet in Houston, Minn. When compared with previous flooding events, the August ‘07 floods had up to 5 times more rainfall.
Scientists report that the flood was so rare, the probability of its existence was once in 500 years, perhaps even once in 1,000 years. The storm’s wrath was comparable to a Category 5 hurricane.
Interestingly enough, the invertebrate count in large streams fell from about 4,000 per square meter to just 1000 after the flood. A specific amphipod, a staple of trout diets, dropped from about 250 per square meter to less than 10.
23.6 inches fell during the month of August, 9.5 inches shy of the average ANNUAL precipitation.
For more on the dangers posed by landslides on the 600 ft high bluffs along the Minnesota and Wisconsin border see our feature from Fountain City, Wis., When Bluffs Throw Boulders. On April 5, 1901 a single boulder fell from the bluff face to smash a home and kill its occupant. Some 85 years later it happened again… in the same spot. This time, the Rock was left in place and is open to the public for viewing at the Rock in the House attraction on Hwy 35.
Tags: bluffs, Flooding, rainfall, trout, Upper Mississippi