“get the Drift” Effects of Snow Fence Variables on Wind Patterns, Snow Drift Geometry and Volume

What are the effects of snow fence variables on wind patterns, and geometry and volume of snow collected in drifts? This question arose from a need to capture winter’s blowing snow to improve water supply during a drought and to protect critical areas from blowing snow. Last year, during the first phase of this project, various powders were tested to find which would closely replicate snow in a small scale drifting model. It was concluded that Cascade Dish Detergent was the best for modeling wind blown snow. In this year’s continuation, Cascade powder was used to further evaluate the relationship of wind blown snow and snow fences. Literature research and professional interviews provided information about water supply from drifted snow, wind flow, drifting patterns, wind tunnel modeling, and snow fence variables, but did not describe the effects of varying horizontal board thickness on the wind pattern or the resulting drifts. The intent of this project was to evaluate relationships of fence thickness and porosity to wind direction and speed, and drift geometry and volume. The model testing system included six scaled model snow fences of varying thicknesses and porosities, a wind tunnel, and apparatus for wind direction and wind speed. Each fence was tested three ways: wind direction, wind speed, and drift geometry. Graphs for each fence were developed to show wind direction and speed, drift profile, and a comparison of wind speed to drift profile. Also, graphs were developed to compare total drift volumes and locations of drift apex for all fences. Three of the four hypotheses were supported. As fence porosity decreased and board thickness increased, pattern of wind direction changed, wind speed decreased, and the drift apex occurred further upwind. The volume hypothesis for thickness was supported because increased thickness resulted in increased drift volume. However, the volume hypothesis for porosity was denied, because increased fence porosity resulted in increased drift volume. Based on these results, snow fences can now be designed for specific intents. Other variables that could be tested next include those of terrain, buildings, and wind intensities. The most valuable extension is application of these fence model results to establish full-size fences to collect the snow in desired locations; this will collect more volume of winter wind blown snow to improve water supply in a drought period and keep critical areas free of drifting snow. This project proves potential to “Get the Drift!” into more helpful locations.