2 



medium river — A river with a drainage area greater than 100 km but less 



2 

 than 1,000 km and a mean annual flow channel top width greater than 



15 m but less than 100 m. 



microhabitat — Localized and more specialized areas within a community or 



habitat type, utilized by organisms for specific purposes or events, or 

 both. Expresses the more specific and functional aspects of habitat and 

 cover that allows the effective use of larger areas (aquatic and ter- 

 restrial) in maximizing the productive capacity of the habitat, (See 

 cover types, habitat). 



mid-channel bar — An unvegetated or lightly vegetated sediment deposit lo- 

 cated between two channels. 



parameter — A variable in a mathematical function which, for each of its 

 particular values, defines other variables in the function. 



permafrost — Perennially frozen ground, 



pit excavation — A method of removing gravel, frequently from below over- 

 burden, in a manner that results in a permanently flooded area. Gravels 

 are usually extracted using draglines or backhoes, 



point bar — An unvegetated sediment deposit located adjacent to the inside 

 edge of a channel in a meander bend. 



pool — A body of water or portion of a stream that is deep and quiet rela- 

 tive to the main current, 



pool, plunge — A pool, basin, or hole scoured out by falling water at the 

 base of a water fal I , 



profile — In open channel hydraulics, it is the water or bed surface ele- 

 vation graphed aganist channel distance. 



165 



