Page 142 - Water Engineering Hydraulics, Distribution and Treatment

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Chapter 5
Water Hydraulics, Transmission, and Appurtenances
Solution 2 (SI System):
a. Specific weight for water at 39 F(4 C) is 62.4lb∕ft (9.81 kN∕m ). Specific weight in SI unit can be calculated as
= ( )(g) = (1,000 kg∕m )(9.81 m∕s )
= 9,810 N∕m = 9.81 kN∕m .
The resultant force, P ,actingonareaAB:
P = ( )(hcg)(A)
f
= (9.81 kN∕m )(3.7m + 1.8m∕2)(1.8m × 2.44 m)
= 198.2kN. 3 3 f 3 ◦ 3 ◦ 2 3 3
b. The location of the resultant force acting on area AB:
y = [I ∕y A] + y
cp cg cg cg
I = (1∕12)bh 3
cg
3
y = [(bh ∕12)∕y A] + y
cp cg cg
3
= (2.44 × 1.8 ∕12)∕[(4.56)(1.8 × 2.44)] + 4.56
= 4.62 m.
c. The pressure, p, on the bottom BC:
3
p = h = (9.81 kN∕m )(1.8m + 3.7m) = 53.9kN∕m 2
= 53.9kPa.
d. The total weight, W,ofthe water:
W = V
2
3
= (1,000 kg∕m )(6.1m × 1.8m × 2.44 m + 3.7m × 0.093 m )
= 26,865 kg.
5.1.2 Transmission Systems 1. The Central Arizona aqueduct is a multipurpose
water resource project that delivers Colorado River
Supply conduits,or aqueducts, transport water from the water into central and southern Arizona (see Fig. 1.6).
source of supply to the community and, hence, form the The aqueduct diversion canal runs about 336 mi
connecting link between collection works and distribution (541 km) from Lake Havasu to a terminus 14 mi
systems. The location of the source determines whether con- (22.5 km) southwest of Tucson. The final extension
duits are short or long, and whether transport is by gravity to Tucson includes a tunnel through the mountains.
or pumping. Depending on topography and available materi-
2. The Colorado River aqueduct of the Metropolitan
als, conduits are designed for open channel or pressure flow.
Water District of Southern California is 242 mi
They may follow the hydraulic grade line (HGL) as canals
(389 km) long and includes 92 mi (148 km) of grade
dug through the ground, flumes elevated above the ground,
tunnel, 63 mi (101 km) of canal, 54 mi (86.9 mi) of
grade aqueducts laid in balanced cut and cover at the ground
grade aqueduct, 29 mi (46.7 km) of inverted siphons,
surface, and grade tunnels penetrating hills; or they may
and 4 mi (6.4 km) of force main.
depart from the HGL as pressure aqueducts laid in balanced
3. The Delaware aqueduct of New York City comprises
cut and cover at the ground surface, pressure tunnels dipping
85 mi (137 km) of pressure tunnel in three sections.
beneath valleys or hills, and pipelines of fabricated materi-
als following the ground surface, if necessary over hill and 4. Pressure tunnels 25 mi (40.2 km) long supply the
through dale, sometimes even rising above the HGL. Illus- metropolitan districts of Boston and San Francisco.
trative examples of supply conduits and aqueducts include 5. The supply conduits of Springfield, MA, are made
the following: of steel pipe and reinforced concrete pipe; those of
Albany, NY, of cast iron pipe.