Nile Landslide LiDAR

December 10, 2009

Sometimes you get a Christmas gift you weren’t expected. I guess in this case, it was more of a birthday gift. LiDAR for the Nile Landslide has finally preliminarily been released to various people to help in analysis on the landslide, but has not yet been released to the general public until the proper QA/QC has been established on the data. If you are working on the Nile Landslide (and I have talked with many of you already) and would like a copy of the LiDAR, contact me and I’ll see what we can arrange.

That being said…

I am going to analyze the lidar a bit more, but some interesting things. You can clearly see some of the uplifted areas, although it might not be as extensive as we previously thought. There are a few secondary landslides within the landslide mass, one major one by the quarry. Near the center of the landslide, there are some odd peaks (near the toe), not sure what those are, but I’ll try and find out today. Anyway, stay tuned, this is a key piece of data to help us understand the Nile Landslide. The Lidar also covers the Sanford Pasture Landslide as well and this will give us clues to the activity and morphology of this landslide as well.

We tried getting into the Pilchuck headwaters yesterday to no avail. Roads were washed out and gates were locked. We did see a number of landslides on the Sultan Basin Road heading up to Olney Pass. These landslides bare the mark of a large rainstorm event and almost certainly moved during the January 7-8th, 2009 storm event

Sultan Basin Road Landslides

Sultan Basin Road Landslides

The picture has a backdrop of 2003(? I think it was later than that) Snohomish County LiDAR.

The most interesting of these landslides is a debris avalanche at the bridge crossing at Olney Creek. It was probably dealt a one-two punch, the swollen Olney Creek was probably eating away at the bank (and probably has been for years) and the saturated ground allowed enough driving forces to overcome the resistive forces. It also moved a good amount of timber into the creek, which might cause a problem down the road by creating a debris dam behind the bridge.

Sultan Basin Rd Debris Avalanche.  Photo by Carol Serdar

Sultan Basin Rd Debris Avalanche. Photo by Carol Serdar

One of the things I have grown up with while working at DNR is LiDAR. Actually, it took me awhile to start using LiDAR, my first projects for identifying landslides used aerial photos and 10m DEMs. Not the easiest way to go once you learn to use LiDAR.
Here is an example of some very clear and fascinating landslides in Whatcom County.

Whatcom County Landslides

Whatcom County Landslides

Isn’t that the best thing since sliced bread???