CIV E 530 - OPEN-CHANNEL HYDRAULICS
SPRING 2005
HOMEWORK No. 5

  1. Determine the normal discharges in channels having the following cross sections, for y = 1 m, n = 0.015, and So = 0.005:

    a.   A rectangular section 6 m wide.
    b.   A triangular section with a bottom angle equal to 60o.
    c.   A trapezoidal section with a bottom width of 8 m and side slope z = 2

    Use onlinechannel.sdsu.edu to verify the results. Report the actual output from ONLINECHANNEL.

  2. A channel reach 450-m long has a fall of 0.15 m in the water surface during a flood. Compute the flood discharge using the following data:

    Subsection A (m2) P (m) n α β
    Upstream main channel 450 70 0.030 1.10 1.06
    Upstream side channel 2580 625 0.050 1.25 1.15
    Downstream main channel 580 78 0.035 1.12 1.05
    Downstream side channel 2690 720 0.045 1.18 1.09

  3. Use CHANNEL in onlinecomp.sdsu.edu to calculate critical and normal depth for the following cases:

    a.   Q = 200 cfs, b = 28 ft, z = 0, So = 0.002, n = 0.030;
    b.   Q = 550 cfs, b = 30 ft, z = 1, So = 0.003, n = 0.035;
    c.   Q = 870 cfs, b = 40 ft, z = 2, So = 0.001, n = 0.040.
    d.   Q = 25 m3/s, b = 4 m, z = 1.5, So = 0.0015, n = 0.032.
    e.   Q = 42 m3/s, b = 6 m, z = 2.0, So = 0.0025, n = 0.037.

    Report the actual output from CHANNEL.