Flooding Impacts

By Dave Sligh


The James was overflowing its banks in a number of places yesterday and many tributaries were roaring in the last several days, with some localized flooding. I'm thankful that I didn't see or hear of any human injuries or death. However, there was lots of damage done to stream channels because of the high flows. It's natural that periodic floods rearrange stream banks and habitats - in fact it's an essential process in the life of the stream. Our activities on the land though cause changes that aren't within the natural range and aren't beneficial.

The first photograph below shows a portion of a stream that I've observed over the last year. While this small section of the stream bank was already eroded and cut down to form a vertical wall of dirt, the recent high waters ripped away all of the dirt in this large depression. I'm not too experienced at estimating amounts of dirt but would guess that at least several tons of soil was carried downstream from a length of stream reaching no more than 100 yards. If you recognize that similar erosion effects occurred in dozens of other places on this same stream and multiply this by the thousands of small streams throughout the James River watershed, you can see the enormity of this problem.

You can see in the second picture (below) the stream bank across from that in the first view. This slope was covered all the way to the top of the slope with large stones (generally known as rip rap) in an attempt to stabilize the portion nearest the adjacent road. Almost all of the stones were washed away during this storm, showing that our human attempts at channel protection are sadly inferior to natural vegetative buffers and land cover.

This small tributary to Ivy Creek, in Albemarle County, is less than one mile in length upstream of the point shown in these photographs and this portion of the stream drains an area of about 0.5 square miles. The land is primarly in pastures with scattered home sites and a relatively small percentage of impermeable surfaces. However, the stream-side vegetative buffers are completely missing or very narrow along at least half of the stream's length. That this small watershed with primarily agricultural land can produce such force and destruction illustrates the extreme importance of maintaining stream buffer plantings and re-establishing them.

Finally, you can click on the link below and see a short news segment from Channel 19 TV in Charlottesville where I was interviewed describing this type of damage from high flows.




http://www.newsplex.com/video?clipID=4490640&autoStart=true&contentID=82706652