VE6AB Mobile Ops
APRS and Satellite Imagery
Satellite view of the Sibbald Flats area in Kananaskis Country with Sibbald creek containing the beaver dams and beaver lodges located there.
Although Beavers actually are classified as a rodent and people may think of them as pests depending where they locate, they are very cool when it comes to building their dams and lodges.
A minimum water level of 0.6 to 0.9 metres (2.0 to 3.0 ft) is required to keep the underwater entrance to beaver lodges from being blocked by ice during the winter. In lakes, rivers and large streams with deep enough water, beavers may not build dams and instead live in bank burrows and lodges. If the water is not deep enough to keep beavers safe from predators and their lodge entrances ice-free, beavers build dams as seen in my insert photos.
Beavers start construction by diverting the stream to lessen the water's flow pressure. Branches and logs are then driven into the mud of the stream bed to form a base. Then sticks, bark (from deciduous trees), rocks, mud, grass, leaves, masses of plants, and anything else available, are used to build the superstructure. The average height of a dam is about 1.8 metres (5.9 ft) with an average depth of water behind the dam of 1.2 to 1.8 meters, although if there is not enough depth for getting around beneath the ice, the beavers will form channels in the bottom of the creek allowing for that. The thickness of the dam is often around 1 m or more. The length depends on the stream width, but averages about 4.5 m long.
Beavers vary the type of dam built and how they build it, according to the speed of water on the stream. In slow-moving water, they build a straight dam, whereas in fast-moving water they tend to be curved. Spillways and passageways are built into the dam to allow excess water to drain off without damaging it. Dams are generally built wider at the base and the top is usually tilted upstream to resist the force of the current. Beavers can transport their own weight in material; they drag logs along mudslides and float them through canals to get them in place. Once the dam has flooded enough area to the proper depth to form a protective moat for the lodge, beavers begin construction on the lodge.
Maintenance work on the dam and lodges is particularly heavy in autumn.
Click on the photo for a closer look....
