more numerous channels. These changes were mos1- prevalent in scraped sites 

 and most prominent in single channel sites. Gravel removal at many scraped 

 and pit excavated sites caused a diversion or a high potential for diversion 

 of flow through the gravel removal site. These observed channel config- 

 uration changes were given quantitative ratings for comparative purposes 

 (Table 5). These changes in channel configuration are discussed in more 

 detail in the following sections. 



Braiding Characteristics. The two braiding characteristics considered 

 were the number and stability of the channels. The most significant changes 

 in these characteristics resulted from scraping operations in straight, sin- 

 uous, split, and meandering rivers with lesser changes observed in scraped 

 braided rivers. This difference was expected, because braided rivers had 

 such characteristics prior to gravel removal, thus, any change was compara- 

 tively less significant. The locations of the gravel removal operations that 

 caused the most significant change in the braiding characteristics were 

 those which disturbed the bars adjacent to active channels or those which 

 caused diversion of flow into the material site. 



Disturbance of the bars adjacent to active channels can hypotheti- 

 cal ly reduce the flow within the channel during fl oods because flow spreads 

 out through the mined area. The reduced flow within the channel would reduce 

 the ability to transport sediments; sediment deposition within the channel 

 may result. This deposition would potential ly aggravate the problem by 

 further reducing the cross-sectional area available to the flow. This pro- 

 cess can result in widening the channel and the development of mid-channel 

 bars. Although the potential for this hypothetical process exists, it was 

 not observed at the study sites. 



Braiding characteristics increased at many sites due to the diversion 

 of flow through the site and the lack of a well-defined channel to confine 

 the flow. The flow thus spread through the material site and likely did 

 not have sufficient scour potential to develop a new channel. Thus, numerous 

 poorly-defined channels flowed through the site. 



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