Manning's equation — In current usage, an empirical formula for the calcula- 

 tion of discharge in a channel. The formula is usually written 



Q = l^R 2/3 31/2 ^_ 

 n 



mean flow — The average discharge at a given stream location computed for 



the period of record by dividing the total volume of flow by the number 

 of days, months, or years in the specified period. 



mean water velocity — The average velocity of water in a stream channel, 

 which is equal to the discharge in cubic feet per second divided by 

 the cross-sectional area in square feet. For a specific point location, 

 it is the velocity measured at 0.6 of the depth of the average of the 

 velocities as measured at 0.2 and 0.8 of the depth. 



meander wave length — The average downvalley distance of two meanders. 



meandering river — A river winding back and forth within the floodplain. 

 The meandering channel shifts downvalley by a regular pattern of ero- 

 sion and deposition. Few islands are found in this type of river and 

 gravel deosits typically are found on the point bars at the insides of 

 meanders. 



2 

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



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. 



400 



