A flow section area

Ac contracted area of flow

Ao orifice area

a area

B average width

bc width

C Chezy factor, general coefficient, concentration of a tracer, or constant

Ca gate angle correction factor

Cc contraction coefficient

Cd discharge coefficient

Ce effective discharge coefficient

Cv velocity of approach coefficient

Cva coefficient to account for exclusion of approach velocity head

Cvf velocity coefficient caused by friction loss

c velocity of sound

D pipe diameter

dv distance water will travel at a given velocity in a pipe of constant diameter

E specific energy

E%QCs error in percent comparison standard discharge

E%QFS error in percent full-scale discharge

e a subscript denoting "effective"

egl energy grade line

F Froude number

Fb canal freeboard

Fc critical Froude number

Fp pressure force

f friction factor

Go gate opening

g acceleration caused by gravity

H total energy head

Hc critical total energy head

h head or height

ha measuring head

hb submergence head

hb/ha submergence ratio

hc critical head

hcm critical hydraulic mean depth

he effective measurement head

hf head loss

hm hydraulic mean depth

hv measured velocity head

h1e h1 + kh

h1 head measure above a weir crest (upstream head)

ªh upstream head minus downstream head (differential head)

hf(1-2) friction head loss between two stations

hgl hydraulic grade line

K constant

k boundary roughness size

kb correction factor to obtain effective weir length

kh correction factor to obtain effective head

L length

Lb cross-sectional width

Le L + kb or effective crest length

N sample number

n friction or roughness factor

PH pinion height

Pw wetted perimeter

p pressure or height of crest above approach invert

Q discharge

Qa actual discharge

Qc critical discharge

Qcs comparison standard discharge

Qs suppressed orifice discharge

Qeq discharge computed using measured heads and the regression equation

QFS full scale or maximum discharge

Qind indicated discharge from device output

Qmax maximum discharge

Qmin minimum discharge

Qt theoretical discharge through an orifice

ªQ% percent deviation of discharge

q unit or partial discharge

Re Reynolds number

Rh hydraulic radius

r ratio of suppressed portion of the perimeter of an orifice to total perimeter

r radius of curvature

S slope or estimate of standard deviation

So invert or bottom slope

Sws water surface slope

s estimate of standard deviation

T time

T top water surface width

Tc top water surface width at critical conditions

t time

td downstream travel time of the acoustic signal

tu upstream travel time of the acoustic signal

ªt difference in times

U equation coefficient or exponent

V mean velocity

Vc critical velocity

Vaxial average axial velocity of water flow

V0 volume

W weight

Xavg mean of a set of values

Xind each individual value from a set of values

Z potential energy head

beta ratio of orifice hole diameter to pipe diameter

gamma unit weight of water

theta angle

nu kinematic viscosity

sigma standard deviation