RESERVOIR SEDIMENTATION ASSESSMENT GUIDELINE - Aneel

Reservoir Sedimentation Assessment GuidelineSediment classification according to granulometry byAGU, American Geophysical Union (Wentworth Classification)GranulometricClassificationMillimeter Micron Feet TylerStandard(mm) (μ) (in) (sifterdiameter)USStandard(sifterdiameter)Very big cobblestone 4096 – 2048 160 - 80Big cobblestone 2048 – 1024 80 - 40Medium cobblestone 1024 - 512 40 - 20Small cobblestone 512 - 256 20 - 10Big stone 256 – 128 10 - 5Small stone 128 - 64 5 - 2.5Very thick gravel 64 – 32 2.5 - 1.3Thick gravel 32 – 16 1.3 - 0.6Medium gravel 16 - 8 0.6 - 0.3 2 - ½Fine gravel 8 – 4 0.3 – 0.16 5 5Very fine gravel 4 – 2 0.16 - 0.08 9 10Very thick sand 2.000 - 1.000 2000 - 1000 16 18Thick sand 1.000 - 0.500 1000 - 500 32 35Medium sand 0.500 - 0.250 500 - 250 60 60Fine sand 0.250 - 0.125 250 - 125 115 120Very fine sand 0.125 - 0.062 125 - 62 250 230Thick silt 0.062 - 0.031 62 - 31Medium silt 0.031 - 0.016 31 - 16Fine silt 0.016 - 0.008 16 - 8Very fine silt 0.008 - 0.004 8 - 4Thick argyle 0.004 - 0.0020 4 - 2Medium argyle 0.0020 - 0.0010 2 - 1Fine argyle 0.0010 - 0.0005 1 - 0.5Very fine argyle 0.0005 - 0.00024 0.5 - 0.24Colloid < 0.00024 < 0.24Notes: 1) For some countries, including Brazil, the following classification is adoptedby ABNT (Atterberg Classification) -Gravel: 76 - 4.8 mmSand: 4.8 - 0.05 mmSilt: 0.05 - 0.005 mmArgyle: < 0.005 mm2) AGU classification is used in these works due to the use of formulas andsoftware developed in Britannic measurement units.ANEEL – Brazilian Electricity Regulatory Agency / SIH – Hydrologic Studies and Information Department101