scraped sites. Long-term increases in suspended load were implied at sites 

 with disturbed areas which contributed fine materials to the flow. Examples 

 of such long-term increases were the access road degradation at Ugnuravik 

 River (Figure 36), the diversion dam at Skeetercake Creek (Figure 37), and 

 several sites with overburden piles or berms containing fine-grained ma- 

 terials. Similar increases in suspended load could occur from accelerated 

 bank erosion at the site. Deposition of fine-grained sediments in several of 

 the gravel removal areas was also observed. Sites with changes in suspended 

 load showed no pattern with the physical site or gravel removal area charac- 

 teristics. 



Apparent changes in bed load were observed at some sites in the form of 

 gravel dunes or loose gravel deposits in and downstream from the gravel 

 removal area. When these deposits occur in the gravel removal area, they 

 could indicate the inability of the flow through the area to carry the 

 sediment load delivered to it or generated within it. Deposition occurring 

 downstream from the gravel removal area would imply that the flow through 

 the area is sufficient to erode the loose gravel from the gravel removal 

 area. It is possible that when these gravels reach the main channel they are 

 transported in the form of another bed form or possibly in suspension. Bed 

 load changes occurred most often at scraped sites in active and high-water 

 channels, and in locations immediately adjacent to such channels. 



ICE CHARACTERISTICS 



Undisturbed Condition 



Ice jamming can occur during breakup when ice floes moving down the 

 river are blocked, thereby blocking subsequent ice floes and eventually 

 creating a surface dam to the flow of ice. Ice jams can cause scour due to 

 increased velocity beneath the ice dam; they can also cause the water level 

 to rise, resulting in increased flooding. Ice jams are normally caused by a 

 constriction in the channel width or depth, a reduction in flow velocity, or 

 manmade structures in the floodplain. 



122 



