- 27 - 



Logging debris left in stream channels can cause damming, channel changes, 

 and channel scouring (27). 



Vegetation removal (either by harvesting or fire) can cause increased 

 streamflows resulting in channel adjustments (35, other citings in 

 following discussion on flow regimes). 



Road construction and skidding operations may also directly affect 

 channel morphology. 



C. Water Balance and Flow Regime 



Watershed flow regime and water balance may be affected by forestry 



practices such as harvesting methods, burning, and road construction. 



Vegetation removal, particularly by clearcutting, reduces interception 

 and evapotranspi ration losses. Snow accumulation may also be enhanced. 

 Increased water yields usually result in watersheds where such activities 

 occur (7,8,16,26,30,31,36,38,39,40,53,54,55,58,59,64,68,71). 



Burn areas (natural and prescribed) maintain a higher soil water content 

 due to reduced evapotranspiration (1,5,10,23,31,35,58,63). This can 

 affect streamflow due to reduced runoff response time to precipitation 

 events and increased water yield. 



Infiltration will improve in harvested and burned areas as revegetation 

 progresses; however, roads retain their impervious character (32,63). 



The following text outlines related studies done in Montana: 

 Bateridge (8) observed more water flowing from clearcut basin streams 

 than from forested basin streams in the Bitterroot National Forest. 



