Slide 2

Methodology and Spatial Analysis

The determination of optimal back country ski regions utilized a non Boolean standardization to reclassify suitability parameters. In the analysis approach the attribute layers of parameters of slope, elevation, predicted avalanche hazard level, and distance from trails heads are standardized to continuous scales of suitability from 0 to 255. Zero represents the least suitable raster cells, while 255 represents the most suitable cells. Rescaling the factors to a continuous scale avoids hard Boolean decision criteria that implies any particular location is absolutely suitable for the given criteria.

Parameter values are weighted according to their significance:

Parameter Function Type Type of Membership Function Control Points Weight

      Predicted Hazard Level      J-Shaped             Monotonically Decreasing             250,1250                     0.4
      Slope                                 Sigmoidal             Monotonically Increasing              15, 30 degrees             0.2
      Elevation                            Sigmoidal             Monotonically Increasing              1000,1600 meters        0.2
      Distance from trail heads     J-Shaped             Monotonically Decreasing             5000,10000 meters     0.2

Optimum predicted hazard level corresponding to maximum suitability occurs for the values of a low hazard ( 0 -250 ). Consequently, the first control point was selected at the value of 250 after which the suitability begins to decline. The second control point value was selected at 1250. Due to the J-shape of the function suitability rapidly decreases prior to encountering the second control point value, which is associated with the greatest degree of risk.

Optimum slope for back country skiing requires the balance of a minimum degree of slope for skiing without too great a degree of slope at which the risk of serious injury outweighs enjoyment. The increasing sigmoidal curve with selected control points of 15 degrees with initiates the growth segment of the curve and 30 degrees with terminates the growth which initiates the lag segment demonstrates the desired suitability rate of change.

Elevations greater than 1000 meters are required to ensure adequate snow pack, however, values greater than 1600 meters are not evident for the North Vancouver region. Further, the rate of growth demonstrated by the sigmoidal curve best illustrates elevation desirability based on ease of access. As elevation increases, access to slopes decreases to a degree at a which a slope becomes equally inaccessible.

Distance, as related to access to desirable slopes decreases rapidly from existing trail heads. This decreasing J-shaped function was selected with an initial control point of 5000 meters or 5 kilometers as an acceptable travel distance rapidly declines as the distance increases to 10 kilometers.