PHYSICAL SITE CHARACTERISTICS 



The Physical Site Characteristics considered in this project were: 

 drainage basin size, channel width, channel configuration, channel slope, 

 and stream origin (Table I). Following study of the 25 material sites and 

 analyses of data, it was established that channel configuration was the most 

 important floodplain characteristic affecting environmental change when 

 combined with gravel removal activities. Drainage basin size (channel width) 

 was found to be less significant, and channel slope and stream origin were 

 found to have little influence on the effects of gravel removal. The follow- 

 ing discussion is subdivided according to these categories. 



CHANNEL CONFIGURATION 



The channel configuration or pattern of a river is the shape of the 

 river channel (s) as seen from the air. The channel configurations considered 

 in this study were braided, split, meandering, sinuous, and straight. 



Bra i ded 



A river with a braided channel pattern typical ly contains two or more 

 interconnecting channels separated by unvegetated gravel bars, sparsely vege- 

 tated islands and, occasionally, heavily vegetated islands. Its floodplain 

 is typically wide and sparsely vegetated and contains numerous high-water 

 channels. The lateral stability of these systems is quite low within the 

 boundaries of the active floodplain. 



Four braided systems used for material sites were studied. Ivishak 

 River on the North Slope, Dietrich River in the Northern Interior, and 

 Tanana River and Phelan Creek in the Southern Interior. These systems usu- 



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