Friday, May 7, 2010

More Trouble in Pakistan

I do a fair bit of landslide work and so try to stay up with the science. I have been following the developments associated with a very large landslide in northern Pakistan. This slide took place in one of the most rugged landscapes inhabited by humans on the planet. It completely blocked the road between Pakistan and China. Its must be an amazing road to travel as it crosses just in front of huge valley glaciers, crosses very active alluvial fans and the entire valley is hemmed in by huge mountains.

I recently took a look at the satellite imagery accessed via Google and found that a newer high resolution view of the area shows the slide and the lake forming behind the slide. An older view of the river prior to being backed up can be seen on the right of the image. The yellow line is a rough approximation of the road route. The lake has inundated the bridge that formerly crossed the river to the northeast in the image.

The risk now is that the landslide dam will fail suddenly as the water levels behind the dam rise. Geologic evidence downstream indicates this sort of event has happened in the past and there are what appears to be lake terraces up stream from past landslide dammed lakes. Pakistan government has been excavating an emergency spillway to reduce the final height of the lake and reduce the risk of a catastrophic breach of the landslide dam. But this is an emergency effort with very limited time. It has been a heroic effort given the conditions and location. One worker was killed from further rockfalls on the slide. He was not able to hear the crashing boulders that were approaching as he was operating an excavator.

As the spring snow melt begins the lake will fill rapidly. The anticipated date of the dam being over topped is in about two weeks. 


Kathleen Faulkner said...

I didn't hear a word about this in the news. Very interesting, I look forward to your update...

Sam Crawford said...

Hey Dan, check this out. Fellow LIDAR geeks unite!

Dan McShane said...


I am looking forward to the day the lake overtops the slide. I will post something more when that happens


This is a very different use for LIDAR than finding fault lines and landslides! Most of the LIDAR I work with utilizes programming that removes the scatter created by trees and buildings. It’s kind of funny because I can spot old roads (even a heavily used elk trail) but the buildings are removed. There are folks that have been using the raw data to do other images including forest health. For example overstocked stands of Douglas fir timber can be spotted because they have more scatter than stands with better spacing between trees.

In the urban environment, LIDAR has lots of possibilities. It has been just a matter of time to get funding and come up with some very creative ideas on how to use this tool in an urban setting. There are also ground base LIDAR devices and I suspect that these types of devices will get lots more use in the future as they can create manipulative 3-D images. I suspect landscape architect will apply this tools for urban planning before too long if not already.