Time-lapse photography is a cinematography technique whereby the frequency at which film frames are captured (the frame rate) is much lower than that which will be used to play the sequence back. When replayed at normal speed, time appears to be moving faster and thus lapsing. For example, an image of a scene may be captured once every second, and then played back at 30 frames per second; the result would be an apparent increase of speed by 30 times.
Processes that would normally appear subtle to the human eye, such as the motion of the sun and stars in the sky, become very pronounced. Another example: Watching a 125 foot tall dam on the White Salmon River be removed in one minute. (ok, that last part’s not from Wikipedia)
The rumor mill is churning at full tilt right now along the shores of the White Salmon. Residents are worried about an unsightly mud pit, whitewater kayakers are getting excited about the possibility of new rapids, and scientists are geeking out. The fact of the mater is, no dam this tall has ever been removed (it’s 125 feet tall), and no dam with this much sediment has ever been taken out (approximately 2.3 million cubic yards–holy toledo). So what going to happen is anyone’s guess. One thing we do know about rivers is that they’re resilient, so if residents’ worst fears are realized and there is a big mud pit exposed, I wouldn’t expect it to stay that way for too long. Guess we’ll find out soon enough though!
Steve Stampfli is the Watershed Coordinator for the Hood River Watershed Group in north central Oregon. He recently worked with PacifiCorp to document the removal of Powerdale Dam on the Hood River, which blocked fish passage for more than 80 years. Steve lives in Husum, WA, a stones throw from the White Salmon. (email Steve)