Friday, August 24, 2007

More on the Olentangy and Ohio Flooding

Last night I went to check the Olentangy River, and the water was up higher than yesterday. Actually, it was higher than I have ever seen it. The first picture is from last night, the second is from two nights ago. Hopefully, the river has crested. Although the two pictures aren't perfectly the same, you can see where the water has risen by comparing the trees. Also, a patch of upland vegetation was completely submerged last night that was dry two nights ago.


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Just for kicks, I went to the USGS Ohio water resources website to see if the Olentangy is retreating. The simple answer, it isn't. I'm sure that water is gradually being released from the Delaware dam, and we might see these high levels for the next day or so. In fact, I just looked again at the USGS site for this stream guage, and they say that the stream is "is completely regulated by the Delaware Dam since 1951." Here is a nice graph provided by the USGS of current water levels on the Olentangy at Worthington, which is just a few miles above where I shot the pictures:

This graph measures the total water flowing through the stream past the gauge. Normally in August, the average is less than 100 cubic feet of water per second. Wednesday night, when the second picture was taken, the river was discharging about 2000 cubic feet of water per second, and last night, that figure had risen to about 3500 cubic feet per second and rising! That is a ton of water!

In fact, according to the USGS, during the last 40 years, we have set a record for August 24th. The highest recorded discharge for this part of the stream on this day was 2990 cubic feet per second, which we reached in 1980.

So, I'm wondering what the maximum discharge recorded for this station has been?

USGS has that information too. Looking at this graph, the Olentangy is holding its own. Discharges of 5000-6000 cubic feet per second happen about every year, although I'm not sure why there is such a large gap in the middle of the graph. I'm glad I wasn't around in the flood that happened about 1960. 15000 cubic feet per second would have been a real doozy.

So, lets turn now to the Blanchard river, which caused all the flooding in Findlay, Ohio.

The Blanchard is rather calm and placid in August, with discharges averaging less than 100 cubic feet per second, about the same as the Olentangy River. So remember, the Olentangy is way up and it is only discharging less than 4000 cubic feet per second. Here is what the Blanchard has done over the last week:

Take a look at the scale. Yes, the river peaked at just under 20,000 cubic feet per second! That is a ton of water, and that is why there was such catastrophic flooding the in the area. When that much water is flowing through the river, it just simply floods its banks and goes where it normally doesn't go. Lets look at the historical graph for the Blanchard to see how this flood compares with historical highs.

And there you go. You have had to been alive in 1915, it looks like, to see have seen a flood like Findlay has experienced. That the peak flow was over 20,000 cubic feet per second! Yes, they do happen, but not very often, at least when compared to the life span of a human being. In geologic time, floods like this are common.

My thoughts this morning go out to all across Ohio that were affected by all of this rain that northwestern Ohio has seen in the past week.


1 comment:

  1. I wanted to add that the Olentangy River peaked out at about 5000 cubic feet per second. This morning, it was back down to the 100 cubic feet per second range.