SPRING 2013
FIRST MIDTERM
FEBRUARY 25, 2013, 1600-1650
Name: __________________ Red ID ____________________ Grade:____ _________
- (25%) A high overflow spillway has a downstream slope after the point of tangency (see figure)
of 0.6 H to 1 V. The Darcy-Weisbach friction factor of smooth concrete
is fD = 0.032.
What is the likely Froude number right after the point of tangency?
- (25%)
On July 31, 1976, the Big Thompson Canyon, near Loveland, Colorado, experienced a record flood event.
The peak velocity was estimated by USGS at 28 fps. The width of the canyon at the measuring site is 55 ft.
Assume critical flow prevailed during the passage of the flood.
Provide an estimate of the peak discharge.
- (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 2.5 in. The discharge coefficient at the weir has been calibrated to be C = 2.92. What is the discharge?
- (25%) Please answer the following questions in a brief statement.
- Why is unsteady uniform flow not possible in practice?
- What width/depth ratio will assure hydraulically wide conditions in an open channel?
- What is a rating in open-channel hydraulics? How many types of rating are there?
- What is the practical range of β (the exponent of the rating) under a wide range of flow conditions, including laminar and turbulent, narrow and hydraulically wide?
- What is the minimum and maximum value of Manning's n encountered in practice? Where do they apply?
- (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 2.5 in. The discharge coefficient at the weir has been calibrated to be C = 2.92. What is the discharge?