The usual mining technique for these sites is to scrape unvegetated gravel 

 bars rather than to excavate deeply, thus, any rearrangement of channels 

 through an abandoned site would closely resemble the natural annual pro- 

 cesses of lateral channel migration. 



In summary, braided river floodplains can be desirable locations for 

 extracting gravels (Table 40). The abundance of well graded materials and 

 the potentially small effect on the physical, biological, and aesthetic char- 

 acteristics suggest the desirability of these areas for material sites. Th i s 

 conclusion assumes that the procedures of shallow scraping of unvegetated 

 gravel bars with minimal disturbance to active channels, banks, and vege - 

 tated areas, and complete rehabilitation of sites during site closure, are 

 adhered to . 



Sp I i t Channe I 



A river with a split channel pattern has numerous islands dividing 

 the flow into two channels. The islands and banks are usually heavily vege- 

 tated and stable (Figure 93). The channels tend to be narrower and deeper 

 and the floodplain narrower than in a braided system. Four split channel 

 rivers were included in this study: the Kavik, Kuparuk, and Sagavan irktok 

 Rivers on the North Slope and the Sinuk River on the Seward Peninsula. 



Although the bed load carrying capacity of split channel rivers is 

 less than for braided systems, they often have a greater carrying capacity 

 than equivalently sized meandering or sinuous rivers. The narrower flood- 

 plains and lack of numerous gravel bars restrict the extent of potential 

 gravel removal areas. Channels, islands, and banks are often used for extrac- 

 tion, as was the case at the four sites studied. Islands and banks typically 

 are vegetated and relatively stable, consequently, there is a direct effect 

 on small mammals, passerines, ptarmigan, and moose utilizing these areas. 

 The long-term terrestrial disturbance is directly related to the extent of 

 vegetation removal and the rehabilitation practices used during site clo- 

 sure. 



337 



