Encyclopedia of Environmental Science and Engineering, Volume I and II

SEDIMENT TRANSPORT AND EROSION 1067

widely used because of their doubtful accuracy. Generally, only

suspended load samples are collected in samplers of the type

shown schematically in Figure 4. This sampler is designed so

that the intake velocity is nearly the same as the local stream

velocity. The extent of the suspended sampled zone is limited

by the size of the sampler. Methods or extrapolating these

measurements and estimating bed load are discussed in the next

section.

For more details of sediment measurement techniques and

equipment, the reader is referred to Nordin and Richardson,^15

01020 30 40 50 60

200

400

600

800

1000

EFFECTIVE PRECIPITATION (inches/year)

SEDIMENT YIELD (tons/sq.mi/year)

T = 50°F

FIGURE 3 Sediment yield in the United States (after Langbein and Schumm).

FLOW

AIR

WATER SEAL

INTAKE

SPRING SAMPLE BOTTLE

EXHAUST VENT

FIGURE 4 Sketch of a suspended load sampler.

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