Discussion of “the efficiency of depth‐integrating suspended‐sediment sampling”

Abstract

The author has developed equations and approximate curves to express the percentage of the total sediment discharge that is carried in suspension above the lowest point reached by the nozzle of a depth‐integrating sediment sampler. He assumes that bed load and suspended load are defined by the equations in a paper by H. A. Einstein [The bed‐load function for sediment transportation in open‐channel flows, U.S. Dept. Agric., Tech. Bull. 1026, 1950]. The percentage is termed the efficiency of sampling. In a vertical strip of unit width, the suspended‐sediment discharge discussed by the author' in effect the product of the mean concentration of the depth‐integrated sample, the water discharge in that portion of the depth above the lowest nozzle position, and a factor for converting the result into desired units, such as tons per day. In contrast, the common operating practice is to compute the suspended‐sediment load as the product of the measured concentration, the total water discharge, and the conversion factor. The difference in computed suspended‐sediment discharge by the two methods is sometimes appreciable as, for example, in the wide, shallow streams that drain the sandhills of Nebraska.