Snow Drift Management: A look at the dynamics of snow drifting and what can be done to keep drifts under control by Mark Bloomer

January 24, 2012 at 9:26am

 

  

 

Drifting snow, like many things in nature, can be quite beautiful but can

also be very challenging and perhaps even dangerous.  When snow falls,

it reaches the ground as a loose web of crystals.  When the wind blows

these crystals, they grind into a fine powder.

 

The wind can pile these finely ground snow crystals into dunes of ice, often compact enough to walk on.  The location and the formation of snow drifts depends on the pattern and behavior of the wind.  Strong and turbulent wind will lift the snow and carry it.  When the wind encounters objects that slow the wind and dampen the turbulence, the snow will settle forming drifts.   

 

A snow fence can be an effective control for drifting snow, slowing the wind

and modifying air turbulence allowing blowing snow to settle around the

fence before reaching roads and parking areas where drifting is undesirable.

 

 

 

This photographs show a snow fence constructed by a driveway.  The

view is looking north.  Strong winds from the west carried blowing snow

“through” the fence where it was allowed to settle before reaching the road.  

 

Two additional photographs following a blizzard showing the snow being deposited  downwind from the snow fence and cresting just before the driveway. 

 

 

 

 

This drawing illustrates the theory behind snow fences.  To the left of the fence, strong gusty winds and low level turbulence carries the snow.  The fence slows the wind and dampens much of the turbulence.  Stronger winds blowing over the fence combine with slower winds in lieu of the fence resulting in clockwise turbulence downwind (looking  north for a west wind). This turbulence helps to further slow the snow and wind which has passed through the fence, allowing snow to settle. 

 

 

Below are diagrams showing the pattern of snow deposition in both porous fences (top illustration and upper sketch in the bottom  illustration) and a solid fence (lower sketch in the bottom illustration). Both diagrams show maximum loads. Note that most of the snow in porous fences is deposited downwind from the fence, but some collects upwind. 

 

 

 

This profile illustrates how a porous snow fence builds its load during consecutive snow/wind events.  Initial deposition is near the fence as the snow builds vertically.  Once the drifting  has reached the height of the fence, more of the load builds  out and away from the barrier.