the bed. Suspended sediment transport rates can also be calculated from the 

 weight of sediment collected w s , the width of the active collection element 

 Aw , and the measurement time At: 



Aw At 



(A4) 



8. The bed-load transport rate qj, (units of weight per unit time and 

 width) can be calculated from the weight of bed load collected g b (units of 

 weight), width of the sampler nozzle Aw (units of length), and sampling time 

 interval At (units of time): 



gb 



q b (A5) 



Aw At 



Riverine Measurement Apparatus 



Suspended load samplers 



9. Riverine suspended sediment samplers can be classified generally as 



instantaneous, integrating, or indirect measuring (continually recording). 



Each category of sampler is defined and discussed below. 



a. Instantaneous capture samplers. After being lowered to a 

 specified depth in a horizontal or vertical position, these 

 samplers collect a water -sediment mixture when triggered. Four 

 types of instantaneous samplers, as described by the Inter- 

 Agency Committee on Water Resources (1963), are listed below. 

 All of these samplers measure the concentration of sediment in 

 the fluid and yield a suspended sediment transport rate using 

 the flow velocity. Because of the variation in suspended 

 sediment transport through time and location, many samples must 

 be collected to assure that the calculated transport rates and 

 suspended sediment distributions will be representative. 



(1) Ordinary Vertical Pipe Sampler 



Ordinary vertical pipe samplers consist of a cylinder 

 with valves on the ends of the pipe that close when trig- 

 gered. As the open sampler is lowered to a specified 

 depth, the water -sediment mixture flows upward into the 

 cylinder. The valves then close when the sampler stops at 



A4 



