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