CIV E 530- OPEN CHANNEL HYDRAULICS
SPRING 2006
FIRST MIDTERM
FEBRUARY 27, 2006, 1600-1715

Name: _________________________ Red ID ________________________ Grade: _______

Instructions: Closed book, closed notes. Use engineering paper. When you are finished, staple your work in sequence (1 to 4), and return this sheet with your work.


  1. (20%) In July of 1976, it rained 6 in in 6 hours in the Front Range of the Rocky Mountains. The Big Thompson river, near Loveland, Colorado, experienced a record flood event, most likely near the Probable Maximum Flood (PMF). The canyon is wide, and the walls are steep. Provide a quick estimate of the flow depth and velocity. Assume critical flow prevailed during the passage of the peak flow.

  2. (20%) The overflow spillway at Turner reservoir, in San Diego County, is 8 ft wide. On February 24, 2005, after several days of heavy rain, the head over the spillway was 5.2 in. What is your best estimate of the discharge?

  3. (20%) An overflow spillway has a slope of 0.6 H to 1 V. The friction factor of smooth concrete (1/8 of Darcy-Weisbach) is 0.004. What is the prevailing Froude number?

  4. (40%) Please answer the following questions in a brief statement.

    1. How many characteristic celerities are there in unsteady open-channel hydraulics? Please define them, using proper names and formulas.

    2. When was the All-American canal built? Why is the proposed lining of the All-American canal opposed by some?

    3. Why is the total discharge Q hydrologic, while the unit-width discharge q is hydraulic? Explain with examples.

    4. In what case does the gradually varied flow assumption fail to apply? Be specific; name an example.

    5. What four forces are usually considered in open-channel flow calculations?

    6. What is a flux? How does energy differ from momentum? In what specific case does both energy and momentum apply?

    7. What equation (or concept) was missing from Chezy's original analysis?

    8. Why did Manning not like his own equation? How do Manning and Checy formulas compare in terms of their advantages and disadvantages? Is the Manning value a constant?