associated with a site located in a vegetated inactive floodplain or ter- 

 race. 



Dikes and stockpiles of gravel and/or overburden left in a material 

 site after closure, have potential effects on the floodplain. These struc- 

 tures can alter channel hydraulics locally if they are subject to high 

 flows. During high water the fines and organic debris may be introduced 

 into the water and result in downstream sedimentation. Depending on their 

 position and orientation relative to flow, dikes and stockpiles can also 

 cause fish entrapment. Where overburden piles are above high-water levels, 

 they can facilitate the establishment of vegetation after site closure. This 

 vegetation provides habitat for small mammals and passerine birds. In some 

 cases, revegetation at a site was found only on such overburden piles. This 

 observation suggests that, as long as the piles are situated where they are 

 not subject to inundation or hydraulic erosion, they can provide a source 

 for revegetation of the site. Overburden piles may detract from the scenic 

 quality of a floodplain. 



RECOMMENDATIONS 



The recommendations developed for each of the disciplines are generally 

 in agreement, with several exceptions. All recommendations are generally 

 designed to minimize change to the floodplain and to enhance re- 

 establishment of pred i sturbance conditions. 



I. River types that should be used in order of decreasing preference are: 

 braided, split, meandering, sinuous, and straight. The major consideration 

 in this preference is the availability of gravel from exposed bars. The 

 largest volumes are available from braided systems and the least from 

 straight systems. An additional factor is the decreasing floodplain width of 

 the configuration series identified above. If areas adjacent to the channel 

 must be used for gravel mining, greater overall change will result in 

 straight systems. 



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