Sunday, November 9, 2008

A storm hydrograph captured on video.

Two years ago, after a couple of attempts, I managed to catch an entire rainstorm and the resulting hydrograph in a small urban channel in Carbondale. I'm guessing nobody else has ever done this. What better way to introduce students to this concept? Here's the YouTube link, I posted a higher resolution version here (you'll need QuickTime).

I compressed the resulting two hours of tape down to two minutes. A tree chipper and a stoplight in the corners of the frame are interesting to watch and give clues to the passing of time. During the flood a checkdam in the center of the frame is overwhelmed. At its peak, the storm is very impressive. Without sound (which you can't use in time lapse) this is harder to appreciate, but the intensity of the rain is apparent.

I added a hydrograph and other graphics. It was a hell of a lot of work, not counting actually getting the event on tape. Even though I have a very heavy tripod, the wind nearly ruined the video--you can see the frame slowly tilt to one side as the tripod settles into the mud. A million things could've gone wrong, especially with a $5,000 camera enduring an hour of driving rain under a thin nylon cape. Had the wind been blowing any other direction except straight from the back of the camera, it wouldn't have worked.

I wasn't paid anything for this, but sure would like to find funding more of the same.


effjot said...

That's a great video! I'd like to use it for a lecture, if you permit.

Just 2 short questions: Could you measure (or estimate) runoff during the event?

What is the second mark on the time bar – the end of rainfall?


Steve Gough said...

Glad you liked it--please do use it for teaching, that's why I make them! Use the link to download a better-than-YouTube version from our website if you like. Feel free to distribute without modification.

We did not measure discharge--I would estimate it was about 20 cfs at the peak. The second mark on the time bar is the hydrograph peak. It's always hard to keep things clean and simple graphically yet still convey necessary information.

Anonymous said...

If you know when the rain ceased, it would be great if you could mark it on the hydrograph as well.