Question

A rectangular channel with slope So = 0.005, n = 0.015. The width is b = 4.0 m and discharge in the channel is Q = 12.0 m/s. If the water depth at a given section along the channel is y: = 0.92 m, determine the distance from the section where the flow depth reaches the normal depth (14 marks). Explain your solution, showing your results in a clearly labelled sketch (6 marks).

Answer 1

Ausyen (liven, So= 0'005 n=0.015 b=4m 8=12 21315 Compute the 10viu al depth of flow by trial y Error weetned. Q=AV a =(BY) R25k RA 125 49 ore 9 ) og veiting Yw 01636 = yn ( - 1999) 14+2yu) Yu h 0.88 m₂ A4, = 0.92 m Y = 0.88 m 7 Length of profile by single step method is :- yi=0.92m vi = 0 = 12 À 480.92332 = 3.264/ Elzy tv, = 0.9 + = 1.46 m 2x9.81 Sfi = n R = 4 = 480.92 4+ 2x0.92 Ž 0.842 : = (3.26 ) ~ (0.015) 0.69421% =0.003

Y2 = 4, = 0.88m V2= 0.12 = 3.4 mis A 0.8884 Ez = Ye + ki = 0.66+ 84) de 2x9.81 -1.47 Sf2 = Vnr . R = 480.88 R₂13 4+ 2x0.88 = 3.45% Co.01c)2 = 0.611 (6.611) 4/ = 0.005 Sf = Sfit Stz = 0.003+0.005 - 0.00u 1.47-1.46 La = 6:005+0.004 = 10 m