Chris O’Leary just sent me some video that he took in Glen Echo during the record-breaking rainfall we had a few weeks ago. After looking at this, the pictures I posted a few days ago make a little more sense in how the debris got so high on the vegetation. It’s amazing the amount of water that came through that day. This run-off is a problem that needs to be addressed, something that will take all of us working together to solve.
Here’s the link: http://www.youtube.com/watch?v=6SehVks2ojk
Until next time!
Lower Olentangy Urban Arboretum 
Wow! That’s a lot of water. It’s a great video, but its unfortunate that our ravine is exposed to that time and time again.
Port Columbus reported 2.04 inches of rain that evening. I believe that locally we may have received a bit more as it was a very narrow storm and it hit our area pretty hard.
If we assume that we had somewhere between 2.04 to 2.84 inches of rain in an approximately 3hour period, that is a 5- to 25-year rain fall! It is a probability (and its with a 90% confidence interval), but that means that on average we should see that type of rain event every 5 to 25 years. Wow!
Keep in mind that it does have a duration component so intensity is factored into the number. We could also end up with a 5 year storm with 1/2 inch of rain in 5minutes or 5 inches over a week.
I think as climate change continues these things are only going to become more frequent and the data will have to be revised. This only makes it more important to decrease impervious surfaces and is another great reason to plant trees.
Some other videos of rain that evening are below:
Walhalla Ravine (at the northern edge of the Arboretum)
Glen Echo east of Calumet St. bridge:
Glen Echo west of Calumet St bridge.