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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 1 Examinations 2009/
Module Title: Water Engineering
Module Code: CIVL
School: School of Building & Civil Engineering
Programme Title: Bachelor of Engineering (Honours) in Structural Engineering Certificate in Energy & Environmental Engineering Programme Code: CSTRU_8_Y EENEN_8_Y
External Examiner(s):Mr. J. O Mahony, Dr. M. Richardson Internal Examiner(s): Dr. J. Harrington
Instructions: Answer Question No. 4 and Two Other Questions
Duration: 2 Hours
Sitting: Winter 2009
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
Q1. (a) A water channel is V-shaped with each side making an angle of 45 degrees to the vertical. Calculate the volume of water passing per second when the depth of water in the channel is 0.5 m and the slope of the channel is 1 in 250. Take the Chezy Coefficient C as
- What would be the depth of water in the channel to pass a flood condition of three times this volume per second if both the slope and the value of C were unaltered? (17 Marks)
(b) Water enters a channel with a depth of 0.15m and a velocity of 3 m/sec. It then passes through a hydraulic jump. Determine the critical flow depth, downstream velocity, depth of flow immediately after the jump and the loss of specific energy in the jump. Outline a typical condition under which a hydraulic jump may form, sketch the water surface profile and classify the water surface profile (the normal depth for the problem outlined without the condition of the hydraulic jump would be 0.4m). (15 marks)
Q2. (a) Discuss (i) River Water Level Measurement (5 marks) (ii) Dilution Gauging (5 marks) (iii) Environmentally Sound River Engineering (5 marks)
(b) A river has the following hydraulic characteristics: Q = 450 m^3 /sec, 50m width, 6m depth and bed slope of 3 x 10 -4^. Find the hydraulic mean depth, the critical bed shear stress, the actual bed shear stress and the minimum stable particle size. If the sediment actually has a typical diameter D 50 of 0.01m estimate the bed load transport rate using Shields (1936) in m^3 /sec and kg/year. Assume the sediment to have a density of 2650 kg/m^3.
(17 marks)
Distance from Supply Point: 1500m, Discharge Elevation: +17m O.D. Point B (the furthest point within the supply scheme) Distance from Supply Point: 1750m, Discharge Elevation: +16m O.D.
Use the attached flow nomogram for a polyethylene pipe. (19 marks)
Open Channel Flow
Chezy Eqn.: v = C mS 0
Manning Eqn.: 01 /^2
2 / 3 v = mn S
Critical Depth:
1 / 3 2
2
B g d Q c
Hydraulic Jump:
1
1 12 2
2 gd d d v
Sediment Transport
τ 0 = ρ gmS 0
τ cr = 0. 056 ( ρ p − ρ) gD 50
Shields Eqn.: (^ )
gD
q qS p p
s cr ρ ρ ρ
ρ τ τ −
