Just ran a bunch of Math. Here is what I've got. First, the baseline numbers:
The Grand River just passed the 34,000 ft^3 per second mark discharge rate in GR. BTW, the area of the Grand River Watershed up to that point is 4900 square miles. That means there are 7 cubic feet of water per second going thru Grand Rapids per square mile upstream. That is about 25,000 cubic feet from every square mile every hour. No shortage of water right now.
Grand River Affects Lake Michigan
Normal Flow: 5000cfs = 37,400 Gal/Sec
Current Flow: 34000cfs = 253,338 Gal/Sec
Amount of Gallons needed to fill Lake Michigan 1 inch: 390 billion.
- Under normal conditions, how long would it take to raise Lake Michigan (not including L. Huron) one inch?
37,400 GAL/SEC x 60 = 2,244,000 GAL/MIN
2,244,000 GAL/MIN x 60 = 134,640,000 GAL/HR
134,640,000 GAL/HR x 24 = 3,231,360,000 GAL/DAY
390,000,000,000 GAL / 3,231,360,000 GAL/DAY = 121 DAYS
- Under current conditions, how long would it take to raise Lake Michigan one inch?
34000 / 5000 = 6.8
121 DAYS / 6.8 = 18 Days
Conclusion: The Grand River has a lot of water, but the big lake can drink a lot and not change!
As a side note, most of Lake Michigan/Huron acquired about 2 inches of water just from direct precipitation. That makes up much of the 3 inches she rose last week. But, the Grand River is not the only river flowing in. Nearly every river in Michigan is running way above average, so it will make a dent in the water deficit. Stay tuned!
From WoodTV8 Meteorologist Bill Steffen:
9:35 PM – I’m running downtown to do the weather at 10 PM and 11 PM by the Ford Museum. Grand Rapids downtown is at 21.4 feet, the forecast crest is 22.7 feet, but I think it’ll be closer to 22 feet and the crest will be Sun. evening. The river at Ionia is down 2″ since crest at midday. The Rogue is falling slowly. The Thornapple has dropped 2 inches at Caledonia.
His blog is:
http://blogs.woodtv.com/author/billsteffen/ if anyone wants to read it.