Saturday, April 19, 2008

Damn Big Dam


A couple of days ago news broke of another Alberta first: a beaver dam 1/2 a mile in length, about 190 klicks NNE of Fort McMurray, just inside Wood Buffalo National Park.

The damn was spotted by researcher Jean Thie when he was playing around with Google Earth in an attempt to determine the effects of Global Warming on Northern Canada's permafrost layer.
Well, it turns out the dam has its own website, courtesy of Mr. Thie, with a whacka whacka good information on beaver habitats in general and this dam in particular. Above is a Google Earth image of the structure, and here is some background:


I emailed Mr. Thie wondering if the growth of the dam (it appears to have existed in a smaller form as far back as 1990) might somehow be attributed to AGW related permafrost melts releasing extra water over the years. He was kind enough to send the following response:

Thanks for your interest and careful reading. No, I do not think that the size of the dam is related to global warming. In the first place the water supply for the wetland comes from the creeks and streams coming down from the Birch Mountains, not from melting permafrost.

Second,this area has only sporadic and isolated patches of permafrost, usually in the form of palsas and peatplateuas in wetlands ( an example :
http://www.geostrategis.com/p_mapm2.htm ). Pemafrost in wetlands in this area was formed after the last glaciation and after the the layers of peat were formed.

This area was burned about (probably a number of times) 20-40 years before 1975 when the black and white aerial photo was taken. The "Poplar Island" is most likely a fire regeneration. Poplar of course is a favourate food for beaver and as you can see on the Google Earth image beavers have build a small dam here.

This link gives you a bit of background on understanding fire history in the boreal zone
http://www.geostrategis.com/p_borealfires.htm

Regards

Jean Thie

So there you have it. Follow the links to see more clearly what Mr. Thie is talking about.

3 comments:

Boris said...

Very cool.

Anonymous said...

A perfect example of how AGW crowds out debate on more important environmental issues.

The issue of bad water in Northern Alberta goes back at least to the account of the 1819-21 overland Franklin Expedition, which reported that Natives south of Ft. Chipewyan suffered from big head-ism; Franklin speculated that it was the water.

Fast forward nearly 200 years later and there is what appears to be a cancer epidemic:

http://www.cbc.ca/sunday/2007/12/120907_4.html

In this context, I have to commend you for staying on top of the AGW angle here, BCL. Good call buddy. Good call.

Unknown said...

Permafrost in Wood Buffalo National Park? LOL