Prairie Smoke: November 2010

The above graph shows a trace of the gage heights of the Minnesota River before, during and after the recent flood event in late September. Note that the river at Mankato was above flood stage for about 9 days, producing damage to roads and some buildings.

The following graph shows streamflow in cubic feet per second (cfs) during the same period. The small brown triangles show what the normal discharge is for these same days of late September and early October. The peak flood discharge was over 80,000cfs; the normal discharge for those days is about 800cfs. That is amazing! The normal discharge indicates that this time of the year is the low water period of the river -- but certainly not this year!

The following map shows that the highest precipitation occurred in an east/west strip over the I=90 corridor with very substantial rains (9-10 inches) in the Mankato/St. Peter area.

And finally, next is a map of the percent of mean rainfall for the month; you can see that we received over 300% of the normal precip for the month. Again, really remarkable!

In early October a controlled burn of the 7-acre Uhler Prairie was conducted by the St. Peter Fire Department. It had been eight years since this prairie was last burned, and thus it was well overdue for a scorching. Fires are essential to a prairie for three reasons: (1) they remove dead and decaying material, (2) they release stored nutrients into the ground and encourage new growth, and (3) they keep trees and other woody plants from spreading into grasslands. Without fires, prairies have a difficult time thriving in the long run. The original native prairies (pre-settlement) were usually started by lightning strikes, but restored prairies are now burned periodically by the various agencies, organizations, and municipalities that manage them. What remains after Sunday’s burn looks and smells like a charred, ashen field, but don’t be discouraged; next spring the prairie will bounce back and appear greener than it has in years. The following is a series of photos from during and after the event.