CIV E 530 - OPEN CHANNEL HYDRAULICS
FALL 2015
FIRST MIDTERM
MONDAY, SEPTEMBER 28, 2015, 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. (20%) A high overflow spillway has a downstream slope after the point of tangency of 0.6 H to 1 V (see detail in right figure). The Darcy-Weisbach friction factor of smooth concrete is fD = 0.032. What is the prevailing Froude number right after the point of tangency?

    		   

  2. (20%) On July 31, 1976, the Big Thompson Canyon, near Loveland, Colorado, experienced a record flood event. Peak flood depths were estimated at 20 ft. The average width of the canyon is 61.5 ft. Assume critical flow prevailed during the passage of the flood. Provide an estimate of the peak discharge.

  3. (20%) A hydraulically wide channel has a mean velocity u = 3 m/s , flow depth y = 2 m, and the flood wave celerity is c = 5 m/s. What are the Froude and Vedernikov numbers?

  4. (40%) 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?

    • What is the neutral-stability Froude number in a wide rectangular channel with Chezy friction?

    • What is the minimum value of Manning's n encountered in practice? Where does it apply?

    • What is the maximum value of Manning's n encountered in practice? Where does it apply?

    • What is the difference between Seddon waves and Lagrange waves? For what flow condition they are the same?

    • What is the physical meaning of the critical slope in a hydraulically wide channel?