Channel configurations vary from straight mountain streams to braided 

 rivers. Factors associated with various types of streams such as bed load 

 movement, bank erosion, and water fluctuation were considered important. 

 Configurations included in this study were braided, split, meandering, 

 sinuous, and straight. 



Channel slope, along with other variables, is a major factor governing 

 water velocity, discharge, and sediment transport. Therefore, streams with 

 s I opes categor i zed as mild, moderate, and steep were included. 



Stream origin was considered because it governs aspects of stream 

 hydrology. Stream origin also influences the amount of bed load material 

 available for transport, thereby indicating the regenerative capacity of 

 a stream, and the availability of suspended sediment that could deposit 

 in a gravel removal area. Categories used were mountain, foothill, coastal 

 plain, and g I ac i a I . 



Other factors such as stream bed material, bank vegetation, and water- 

 shed characteristics are important, but were not considered as major vari- 

 ables. To a large extent these factors are accounted for by the major vari- 

 ables and the physiographic provinces occurring within the regions. 



Gravel Removal Area Characteristics. Two major types of gravel removal 

 operations used in floodplain areas are pits and scrapes, distinguished 

 primarily by depth of excavation and permanent inundation by water after 

 site closure. During site visits it was apparent that pits were either 

 connected or not connected to an active stream channel. Because magnitude 

 of change to a system could be greatly influenced by this factor, pits 

 were characterized as either connected or not connected. 



Location of gravel removal sites within a floodplain influences the 

 degree of impact and the regenerative potential of a site. Therefore, dis- 

 tinctions were made between sites located in a channel, adjoining a channel, 

 and separated from a channel. 



16 



