Wind-blown Snow as a Water Resource
Basics of Blizzards and Snowdrift Control

Snow Fence Equilibrium Drifts
As blizzards build the downwind and the upwind drifts around a snow fence, a smaller part of each blizzard's drifting snow is trapped (Tabler and Jairell 1993). Finally these drifts reach a distinctive shape, and a size that does not grow. Blizzards pass without losing snow, and we say the drift is at equilibrium with the blizzard winds. Storms may add a little snow, strong winds erode the drift slightly, but over several storm cycles, the drift cross section doesn't change much.

We use this equilibrium snowdrift cross section to compute how much snow transport the snow fence will trap. From the snow fences on I-80, we learned that the size and shape of equilibrium drifts scale with fence height H (Tabler 1980b, 1986). The maximum drift depth develops near 6H downwind and is about 1.2 times the fence height. The upwind drift develops slowly, until it extends to 15H and reaches maximum depth near 0.5H just upwind of the fence. One of the dimensions most surprising to us was how far the downwind drift extends. If the distance between the fence and road or other object is less than 34 times the fence height, then the equilibrium drift will reach the object. That can make a drift problem worse, instead of eliminating it.

In this photo, the drift downwind of a 12.4-ft Wyoming snow fence is near equilibrium (Tabler 1986). Wind is from the left.

To Basics of Snowdrift Control