D-R-A-F-T
American Geophysical Union Sediment Classification System
Sediment Size Range
Sediment
millimeters
microns
Inches
Very large boulders
4096-2048
160-80
Large cobbles
256-128
80-40
Medium boulders
1024-512
40-20
Small boulders
512-256
20-10
Large cobbles
256-128
10-5
Small cobbles
128-64
5-2.5
Very coarse gravel
64-32
2.5-1.3
Coarse gravel
32-16
1.3-0.6
Medium gravel
16-8
0.6-0.3
Fine gravel
8-4
0.3-0.16
Very fine gravel
4-2
0.16-0.08
Very coarse sand
2.0-1.0
2000-1000
Coarse sand
1.0-0.5
1000-500
Medium sand
0.5-0.25
500-250
Fine sand
0.25-0.125
250-125
Very fine sand
0.125-0.062
125-62
Coarse silt
0.062-0.031
62-31
Medium silt
0.031-0.016
31-16
Fine silt
0.016-0.008
16-8
Very fine silt
0.008-0.004
8-4
Coarse clay
0.004-0.002
4-2
Medium clay
0.002-0.001
2-1
Fine clay
0.0010-0.0005
1.0-0.5
Very fine clay
0.0005-0.00024
0.5-0.24
Sediment concentration
The weighty of dry sediment in a water-sediment mixture per volume of mixture and
is expressed in milligrams/liter (mg/l), or sometimes parts per million (ppm).
Sediment discharge
The mass or volume of sediment (usually mass) passing a stream cross section in a
unit of time. The term may be qualified, for example; as suspended-sediment
discharge, bed load discharge, or total-sediment discharge.
164 Glossary of Terms
Users Guide To SED2D-WES
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