The Impact of Hurricane Irene in Vermont

The Impact of Hurricane Irene in Vermont

By: Kellie Brenton

Figure 1. Sediment pile on Highway 131 in Cavendish, Vermont after Hurricane Irene. (My own photo)

When hurricane Irene made landfall in Vermont, there was a record rainfall of 5-11 inches in a matter of hours. During the summer months, rainfall in Vermont is very low and the rivers are typically very shallow. The rivers were so small that when hurricane Irene dumped over 8 inches of water in a matter of hours, the rivers weren’t able to handle the amount of water. The rainfall was so rapid that the small streams couldn’t handle the high water levels and resulted in flash flooding.

Figure 1 is a photo I took on the main road along the Black River in Cavendish, Vermont. In the figure there is sand that has been pushed into a pile allowing for cars to still use the road. After the flash floods, the sand covered whole width of the road, and in some places the sand was up to a foot thick. The sand took weeks to be fully cleaned off the road and returned back to the river.

In Figure 1, the main road is paved, but in Vermont it isn’t uncommon to have “dirt” roads, in fact the majority of the back roads in Cavendish are “dirt”. The flash flooding was so powerful that some of the dirt roads, including the dirt road my house is on, were partially washed away. Flash flooding allows for large amounts of sediment transport. The floods in Vermont were so forceful that large pieces of gravel and some small “boulders” were able to move close to two miles downstream. There is a small stream that follows the road leading up to my house, but because of the flash flooding, the stream matched the width of a two-lane“dirt” road.

Figure 2. The stream and dirt road leading up to my house, damaged from Hurricane Irene.

In Figure 2, the left side of the image is the stream that follows the road until it reaches the main channel. The right side of the image is what use to be a two-lane “dirt” road, but is now barely wide enough for one car. The rocks seen in the bottom left corner of the image had not been in the middle of the stream prior to Hurricane Irene, rather they used to be along the inner channel bank. The majority of the bank erosion is found along the bank where the channel is the faster, which in this case would be the outer bank where the stream meanders. Besides the erosion, there was also undercutting that led to slop failure. Figure 2 is an example of how the majority of the “dirt” roads looked after Hurricane Irene.

Fast forward to present day Vermont and almost everything is back to looking the way it did pre-Hurricane Irene. The road to my house has been repaired and reinforced, the main roads are no longer covered in sand, and the stream is now a transparent grey, rather than a murky brown from the suspended sediment.