Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

267 OK ENGINEERING KUKMULÆ. Flow of Rivers, &c. FOKMUJLÆ DEDUCED FROM EXPERIMENTS ON THE MISSISSIPPI. A = Area of cross-section. p =c Length of wetted perimeter. W = Width of river at surface of water. R = Mean radius = -—~ • P + W A D = Hydraulic mean depth = — • fall s = Slope of channel; or•----— • r ’ length V — Mean velocity. 1-69 K = - — • 12 V = [V '0064 K + (195 K Vs)* _ for a channel with rectangular cross-section. V — [V -0081 K + (225 R ^/7)* - -09 V k]2 for a river channel. W = [ V 225 R V« ~ ’OSHs}2 for rivers whose mean radius exceeds 12 or 15 feet. Flood Discharge of Rivers in India. (Colonel Dickens’ formula.) Bengal. D = Maximum flood discharge in cube feet per second, L — Length of river miles. M = Square miles of drainage area. D = 825 M*. In Madras, D = (Benge) - CV M2 5 (Ryves). C — 450 within 15 miles of the sea; = 562-5 between 15 and 100 miles ; = 675 for limited areas near hills.