CIV E 530 - OPEN-CHANNEL HYDRAULICS
SPRING 2012
LAB No. 7:  STEADY GRADUALLY VARIED FLOW I


Note: To save paper, summarize results of onlinewsprofilesxx. Do not include tabular output as part of your work.

  1. A perennial stream has the following properties:   discharge Q = 14 m3/s, bottom width b = 8 m, side slope z = 2, bottom slope So = 0.003, and Manning's n = 0.035. A 2.5-m high diversion dam is planned on the stream to raise the head for an irrigation canal.

    • Calculate the normal depth.

    • Calculate the total length of the M1 water-surface profile. Use three resolutions: (a) n = 100 and m = 100, (b) n = 200 and m = 200, and (c) n = 400 and m = 400. Comment on the results.

    • Using the higher resolution results, calculate the partial length of the M1 profile, from the dam location to a point upstream where the normal depth is exceeded by 1%.

    Use ONLINE CHANNEL 01 and ONLINE WSPROFILES 21.

  2. An overflow spillway flows into a mild channel, producing a hydraulic jump. The channel is rectangular, with Q = 3 m3/s, bottom width b = 5 m, and Manning's n = 0.015. The flow depth at the toe of the spillway is 0.15 and the approximate slope at the toe of the spillway is 0.1. The slope of the downstream mild channel, which functions as a stilling basin, is 0.00016. Use m = 100 and n = 100. Calculate:

    • the critical depth,

    • the length Ltc from the toe of the spillway to critical depth downstream,

    • the Froude number at the toe of the spillway,

    • the Froude number downstream of the hydraulic jump,

    • the sequent depth y2 (the normal depth downstream of the hydraulic jump),

    • the length Lj of the jump, assuming Lj = 6.2 y2

    • the minimum length of the stilling basin Lsb = Ltc + Lj

    What would be the length of the stilling basin if the bottom width were to be increased to 6 m?

    Use ONLINE CHANNEL 02 and ONLINE WSPROFILES 23. In the latter, use n = 100 and m = 100.