Gravel removal from active and high-water channels generally caused 

 local slope redistribution. Removing gravel from bars and banks immediately 

 adjacent to channels also appeared to cause a local redistribution of the 

 water surface slope. An example of a local slope redistribution, which is 

 similar to the situation at the Dietrich River-Downstream site, is schemat- 

 ically illustrated in Figure 34. 



loodplain 



•Water Surface 

 , Bed 



— Floodplain 



Water Surface 

 Bed 



After Gravel Removal 



Figure 34. Schematic diagram illustrating an example of a change In local 

 water surface slope that resulted from an in-channel gravel removal 

 operat i on. 



Flow Obstructions. Flow obstructions in the form of material stock- 

 piles, diversion dikes, and overburden piles had a larger potential for 

 hydraulic disturbance on small rivers than those on medium and large rivers. 

 This larger potential exists because the flow obstructions would have to be 

 placed closer to the active channel due to the typically smaller floodplain 

 width. There were no significant hydraulic impacts observed due to flow 



14 



