APPENDIX A 



FLOOD-FLOW BUFFER DESIGN 



INTRODUCTION 



Flood-flow buffers should be designed to prevent the diversion of an 



active channel through the material site. The design life is usually some 



finite period ranging from 5 years for some scraped sites to possibly 50 years 

 or more for some pit sites. 



The recommended design procedure is to consider the lateral activity 

 of the particular river based on its channel configuration and historical 

 migration pattern. The river size, soil composition of the buffer material, 

 vegetative cover, permafrost banks, and channel aufeis are also important 

 considerations affecting the stability of the buffer. The hydrology of the 

 river must be considered to evaluate the frequency that the buffer will be 

 flooded. Each of these are discussed in more detail in the following sections. 



BUFFER WIDTH 



Lateral Channel Migration 



The general procedure for estimating the amount of channel migration 

 of a river is summarized in this section. The user is referred to Brice (1971) 

 for a more detailed explanation of the procedure. Stereop lot ters, when avail- 

 able, are a faster and more accurate means of estimating lateral migration. 

 Additional information on stereop lot ter use can be obtained from photogram- 

 metry textbooks, photogrammetr ic consultants, or stereop I ot ter manufacturers' 

 I i terature. 



Because of the complexities of the bank erosion process, quantifying 

 lateral migration usually involves the use of historical records. These are 

 projected based on a knowledge of the channel configuration and other con- 

 siderations discussed later. Aerial photographs are obtained of the reach of 



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