Tuesday, January 18, 2011

Do Trees REALLY Prevent Mudslides?

The rain keeps falling and the mud keeps sliding. 

It has been almost a year since I wrote an article for another of my blogs entitled, "Trees and Mudslides." It describes what we learned in Seattle during the mid-90s about what does, and does not, contribute to mudslides. Much of what we discovered observing the aftermath of many, many slides during that time ran completely contrary to what we believed and taught homeowners.

Unfortunately, it does not appear that this new information has come to the attention of very many people. So after a slide occurs, when people are upset and emotions are running high, there's a lot of arguing and finger-pointing that goes on about trees on slopes (among other things). Some people are angry because trees have been cut down. Some are angry because none were planted to hold the slope in the first place.

However, from what we know now, we can see that planting trees on a particular slope might have been a terrible choice and cutting down existing trees might have kept the slide from being far worse. Sometimes trees help and sometimes they don't. When you have all the information, you'll see that there are no easy answers.

If you live in an area on or near a slope, I highly recommend that you read this post. In it you will find links to the USGS survey and reports commissioned by the city of Seattle to investigate the causes of slides that occurred during the winter of 1996-7. Specific areas of the city are described in detail, which you may find very useful if you live in those areas or are considering living there.