Winter-Only Access 



Winter access to a floodplain site is generally easier than summer 

 access because the surrounding terrain is frozen and river levels are low. 

 However, even frozen organic mats need to be protected from mechanical 

 crushing and ripping created from multiple passes over an unprotected access 

 road while building snow or ice roads. 



The Ugnuravik River site provides an example of adverse long-term 

 effects: access to the site was via a temporary winter trail across the 

 frozen North Slope tundra. As far as is known, the trail was used only 

 during the last week of March 1969. However, as was commonly done, the 

 tussocks may have been bladed off to provide a smoother riding surface. 

 Compaction and destruction of the vegetative mat started an irreversible 

 process of thermal erosion. When the site was visited in summer, 1977, the 

 road had eroded to a depth of 1.5 to 2.5 m over a distance of 90 to 120 m. 

 Erosion was continuing, and a permanent scar had been created on the land- 

 scape (Figure 92; also refer to Figure 83). Based on the current state of 



Figure 92. Thermal erosion near Ugnuravik River resulting 

 from compaction and destruction of the vegetative mat over- 

 lying ice-rich permafrost soils. 



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