CIV E 530 - OPEN CHANNEL HYDRAULICS
SPRING 2012
FIRST MIDTERM
FEBRARY 27, 2012, 1600-1650

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. (25%) A high overflow spillway has a downstream slope of 0.6 H to 1 V. The friction factor of smooth concrete (1/8 of Darcy-Weisbach) is f = 0.004. What is the prevailing Froude number?

  2. (25%) On July 31, 1976, the Big Thompson river, near Loveland, Colorado, experienced a record flood event. Provide a quick estimate of the flow depth (m) and velocity (m/s). Assume critical flow and q = 40 m2/s.

  3. (25%) 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 3 in. What is your best estimate of the discharge?

  4. (25%) Please answer the following questions in a brief statement.

    • Why is unsteady uniform flow not possible in practice?

    • What four forces are used in open-channel flow analysis?

    • What width/depth ratio will assure hydraulically wide conditions in an open channel?

    • Why is it improper to refer to Manning's n as a constant?

    • What is the minimum and maximum value of Manning's n encountered in practice? Where do they apply?