Autumn has come to Addison County. Many of the trees along the Middlebury River are covered in colorful leaves.
Some of the leaves find their way into the river, where they float downstream, occasionally finding themselves clogged in 'leaf jams'. I found myself wondering if this has an effect on water flow.
The little leaf dams do seem to slow down the water a bit, but when the water rises during storms, they are washed away. In smaller streams the accumulated leaves probably do have an effect during high water, but its hard to say whether the little dams do much to slow floods. The leaves probably do a better job reducing runoff when they are still attached to the tree.
In urban settings, autumn leaves have a much more detrimental effect - they tend to get caught in drains and cause localized street flooding.
There is another factor that can increase water flow when trees lose their leaves.
Soon all the leaves will have fallen from the deciduous trees along the river, and I'll get to watch ice start to form. Meanwhile, you can click here to see more photos of this year's fall color in Vermont.