TM 5-818-5/AFM 88-5, Chap 6/NAVFAC P-418
APPENDIX B
NOTATIONS
Area of filter through which seepage is passing, drainage area, radius of a circular group of wells; area of
permeability test sample, area of entrance section of pipe in measuring flow through a venturi meter
or with a Pitot tube, or area of stream of water at end of pipe in jet-flow measurement
Cross-section area of sand drain
-Equivalent radius of a group of wells
Area of orifice
Spacing of wells or wellpoints
Distance between two lines of wells, length of weir crest, or circumference of a vertical pipe in fountain
flow calculations
Width of drainage slot, or end dimension of a rectangular drainage slot
Half width of rectangular array of wells
Half length of rectangular array of wells
Coefficient for friction loss in pipes; coefficient for empirical relation of D10 versus k; coefficient for
empirical relation of k versus R; calibrated coefficient of discharge in measuring flow through a ven-
turi meter or orifice; coefficient for measuring flow with a Pitot tube; or center of a circular group of
wells
Coefficients for gravity flow to two slots from two-line sources
Weighted creep ratio for piping
Factors for drawdown in the vicinity of a gravity well
Coefficient of runoff
Thickness of homogeneous isotropic aquifer, or inside diameter of a discharge pipe
Thickness of equivalent homogeneous isotropic aquifer
Effective grain size
Thickness of a pervious stratum, or pressure tap diameter
Pipe diameter
Orifice diameter
Transformed thickness of homogeneous, isotropic pervious stratum
Electrical potential difference or voltage
Extra-length factor
Effective area factor
Factor for computing drawdown at any point due to a group of wells with circular source of seepage, or
freeboard
Factor for computing drawdown at any point due to a group of wells with line source of seepage
Factor for computing drawdown midway between end wells of a line of wells with a circular source of
seepage
Factor for computing drawdown midway between end wells of a line of wells with a line source of seep-
age
Factor of safety
Factor for computing drawdown at center of a group of wells with circular source of seepage
Factor for computing drawdown at center of a group of wells with line source of seepage
Factor for computing drawdown at a well m in a two-line well array with a circular source of seepage
Factor for computing drawdown at a well in a group of wells with circular source of seepage
Factor for computing drawdown at a well in a group of wells with line source of seepage
Correction factor for a partially penetrating well from Kozeny's formula or Muskat's formula
Groundwater table or level
Acceleration of gravity, 32.2 feet per second squared
Height of water table (initial) or piezometric surface, or crest height in fountain flow measurement;
gravity head
B-1
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