265 OK ENGINEERING FOKMULÆ.
Table of Proportions of Channels in Terms of their
Abea, A. (P = Wetted perimeter.)
B
b .
__±_
Angle of Slope a. Slope. Depth. d.
90° Vertical. •707 VÄ
60° •577 to 1 •76 VÄ
45° 1 to 1 Va
36° 52' to 1 •707 Vä
30° 1-73 to 1 •664 VA
26° 34' 2 to 1 •636 VÄ
Semi- circle. ’’ •708 VÄ
Top. B. Bottom. b.
1-414 VÄ 1-414 x/Ä 2'828
1-755 VA •877 VA 2-632
2-092 a/A •613 VA 2-704
2’637 a/A •471 2-818
2-656 •358 VA 3-012
2-844 •3 a/A 3-144
1 ■ 596 2 -501
KUTTEb’s FORMULA FOK DISCHARGE OF WiTEK IN
Channels.
C = Coefficient of mean velocity.
v — Mean velocity, feet per second.
R = Mean hydraulic radius.
S = Sina of inclination of water surface or fall in a length of 1.
n = Coefficient dependent on the lining of the channel.
a, r,andm = Constants. a = 41-6; r = 1’811; »» = -00281.
m= • 009 for well-planed timber.
= •010 for cement plaster.
= •011 for cement and sand
plaster.
= •012 for unplaned timber.
— '013 for ashlar and brick-
work.
= •017 for rubble.
«=•02 for canals, fine gravel.
= ■025 for rivers in perfect
order.
= •03 for rivers in moderate
order.
= ■035 for rivers in bad
order.*
v=c Vrs.
* Overgrown and strewed with stones or detritus.