CIV E 530 - OPEN-CHANNEL HYDRAULICS
SPRING 2007
HOMEWORK No. 4

  1. Using the theory of critical flow, calculate the discharge (in m3 s-1) over a broad crested weir of length L = 10 m, when the total head above the weir crest is H = 0.3 m. Assume negligible approach velocity. Recalculate with L = 32.81 ft and H = 0.984 ft. What is the ratio between the first calculation (metric) and the second (U.S. customary)? Verify using onlinechannel14.php in onlinechannel.sdsu.edu. Show hand calculations and output from onlinechannel14.php

  2. Compute critical depth and velocity for the following cases, using CHANNEL in onlinecomp.sdsu.edu.

    a. Q = 800 m3/sec, B = 90 m, z = 1
    b. Q = 1500 cfs, B = 45 ft, z = 1.5
    c. Q = 2500 m3/sec, B = 155 m, z = 2
    d. Q = 3000 cfs, B = 125 ft, z = 1

    Assume suitable values of bottom slope and Manning's n. Show output from CHANNEL.

  3. What is the slope that will produce critical flow in a rectangular channel with Q = 10 m3/sec, B = 3 m, and n = 0.015? Use trial and error with CHANNEL in onlinecomp.sdsu.edu. Show final output from CHANNEL. Use four significant digits for answer.