30 July 2011

Landslides associated with tree felling in New Zealand

Posted by Dave Petley

Driving from the ferry port at Picton to my overnight accommodation in Nelson today, I decided to spend some time exploring this area of the South Island of New Zealand.  In the Sounds area I came across an area that had recently been cleared of timber, with three interesting types of landslide:

In this felled area (note that it has been replanted) now there was strong erosion and shallow landsliding in the vicinity of the gullies.  This has clearly presented substantial problems for the road.

Near to the road itself the slope has started to actively slip, with a block that extends 15 m or so from the edge of the highway showing active deformation.  Note the fresh scarps quite high up on the hillside.

Perhaps most interestingly, the logging road that crosses the slope is suffering very serious landslide problems, with multiple slips on the upslope side and debris accumulating on the downslope portion.  The damage to the environment is clearly quite severe at this point.

Tomorrow I head over the mountains to Christchurch, so I’ll try to get some further images online in the evening.