CIV E 530 - OPEN-CHANNEL HYDRAULICS
FALL 2013
LAB No. 09:  STEADY RAPIDLY VARIED FLOW

  1. An emergency spillway is being considered for the East Demerera Water Conservancy, in Guyana, to safeguard the integrity of the dam under conditions of climate change. Assume that the existing relief sluices would be inoperable during a major flood due to high tailwater. Determine the length of the free-overflow spillway required to pass the Probable Maximum Flood. The following data is applicable:

    • 10,000-yr 1-day precipitation:   428 mm

    • Hydrologic abstraction:   18 mm

    • Contributing drainage area:   582 km2

    • Time base of the flood hydrograph:   3 days

    • Embankment crest elevation:   18.288 m

    • Spillway crest elevation:   17.526 m

    • Freeboard:   0.3 m

    • Weir discharge coefficient:   1.45

    For simplicity, assume a triangular-shaped flood hydrograph. Use all the freeboard to contain the 10,000-yr flood.


    Emergency spillway, Boeraserie Conservancy, Region 1, Guyana.

  2. Calculate the discharge through a 90° V-notch weir with the following data: Head H = 0.2 ft; width B = 1.2 ft; height P = 0.4 ft. Use Online V-notch weir calculator.

  3. Calculate the discharge through a 90° V-notch weir with the following data: Head H = 0.2 ft; width B = 0.8 ft; height P = 0.4 ft.