EQUIPMENT & SUPPLIES--Bedload samplers; Use of Helley-Smith Sampler (Addendum to QW Branch Technical Memorandum No. 79.17) 


In Reply Refer To:                       February 5, 1980
EGS-Mail Stop 412


QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 80.07

Subject: EQUIPMENT & SUPPLIES--Bedload samplers; Use of 
           Helley-Smith Sampler (Addendum to QW Branch 
           Technical Memorandum No. 79.17)

Please attach this memorandum to all copies of Quality of 
Water Branch Technical Memorandum No. 79.17 on this subject. 
Our WRD bedload researchers have indicated that item 4 under 
Provisional method should include less restrictive 
alternatives relative to compositing of samples.

Item 4. should read:

4. Depending upon the objective of the sampling program, 
bedload discharge can be computed by analyzing (l) each 
sample individually (40 analyses), (2) a composite of the two 
samples collected at each sampling station (20 analyses), (3) 
a composite of the 20 samples collected on each of the two 
traverses (2 analyses), or (4) a composite of all 40 samples 
collected (l analysis). It is strongly recommended that, 
whichever method of compositing is selected for computing 
bedload discharge, an analysis of particle-size distribution 
be made so that the sizes of sediment being moved at the 
computed rate of transport will be known. Remember that the 
more samples one composites, the less one learns about 
variability in space and time.



                           R. J. Pickering

WRD Distribution:  A, B, FOL