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Bibliography 27
PROBLEMS/QUESTIONS

1.1 What is the stream flow in MGD (MLD) for a catchment rate 45 in./year 114.3 cm/year; (c) annual evaporation rate
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area of 80 mile (207.2 km ) where rainfall rate is 45 in./year 20 in./year 50.8 cm/year; (d) water resource development
(114.3 cm/year) and evaporation rate is 20 in./year (50.8 75%; (e) raw water reservoir volume to store 50% net annual
cm/year)? yield or provide half of a year’s water supply, whichever is
1.2 A city is served by a raw water reservoir that has a water higher 13 BG 49.205 BL; and (f) water consumption rate
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surface of 5.8 mile (15.02 km ) and an average effective depth 150 gpcd 568 Lpcd.
of 18 ft (5.49 m). Determine the water storage volume. 1.9 Determine the number of people who can be adequately
1.3 The population of a city is 400,000, and the average daily supported by a watershed under the following conditions:
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(a) watershed area 80 mile 207.2 km ; (b) water supply
per capita water demand is 150 gpcd (567.75 Lpcd). Determine
system with no reservoir for water storage; (c) low-water flow
the city’s average daily water demand. 3 2 3
0.1 ft /s 64,600 gpd per mile 2.83 L/s 0.00283 m /s;
1.4 How many days of draft can a raw water reservoir sup-
and (d) water consumption rate 150 gpcd 568 Lpcd.
port for a city of 400,000 people? The reservoir has a water sur-
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face of 5.8 mile 15.02 km and an average effective depth of 1.10 Make a rough estimate of the groundwater movement
velocity (ft/day or m/day) if (a) all of the groundwater laterally
18 ft 5.49 m.
within 400 ft (122 m) of the well comes fully within its influ-
1.5 What percentage of mean annual runoff is to be consumed
ence; and (b) the yield of the aquifer is 258 gpm (gallon per
by a city of 400,000 people in an area with (a) rainfall rate 45 minute) 976.53 L/min 16.28 L/s; and the aquifer through
in./ year 114.3 cm/year; (b) evaporation rate 20 in./year which the groundwater moves is 25 ft (7.62 m) deep.
50.8 cm/year; and (c) watershed catchment or drainage area 2 2
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80 mile 207.2 km ? 1.11 Estimate the surface area (ft , or m ) of a slow sand fil-
ter that is to deliver water to a village of 1,000 people assuming
1.6 Determine the net yield and water storage volume of a rain-
that (a) the average daily water demand 100 gpcd 378.5
water system assuming that (a) the net yield of a rain collection
Lpcd; (b) the slow sand filter’s filtration rate is 3 million gallons
facility approximates two-thirds of its gross yield; (b) the mean
per acre per day (MGAD) 3 MGD/acre 28.08 MLD/ha
annual rainfall 25 in./year 63.5 cm/year; (c) the mean annual 2
2,808 MLD/km ; and (c) two slow sand filters are required.
evaporation rate is 8 in./year 20.32 cm/year; (d) the rain collec- Each filter is able to treat the full water flow and one of the two
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tion roof area equals 3,200 ft 297.28 m ; and (e) water storage
filters is a standby unit.
volume equals 50% of annual net yield.
1.12 Estimate roughly the size of a water supply pipe leading to
1.7 Determine the storage volume of a new raw water reservoir
a water distributing reservoir serving a small village of 2,000 peo-
in accordance with the following given technical information:
ple assuming that (a) the water consumption rate is 100 gpcd
(a) city population 400,000; (b) water consumption 150 gpcd 378.5 Lpcd, and (b) water velocity in the pipe 3 ft/s 0.91 m/s.
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568 Lpcd; (c) watershed or catchment area 80 mile
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207.2 km ; (d) rainfall rate 45 in./year 114.3 cm/year; 1.13 Determine the diameter of a water main to serve a residen-
tial area, assuming (a) an average water demand of 150 gpcd
(e) evaporation rate 20 in./year 50.8 cm/year; (f) minimum
568 Lpcd; (b) population 30,000; (c) fire flow requirement
reservoir volume 50% annual net yield, or half of a year’s
500 gpm 2,082 L/min 32 L/s; and (d) recommended water
water supply, whichever is greater; and (g) 75% water resources
velocity 3.5 ft/s 1.07 m/s.
development.
1.8 Determine the number of people who can be sustainably 1.14 Roughly, what is the replacement cost of the waterworks
of a city of 10,000 people?
supported by a watershed under the following conditions:
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(a) watershed area 80 mile 207.2 km ; (b) annual rainfall
BIBLIOGRAPHY
Al-Dhowalia, K., and Shammas, N. K., Leak Detection and Quanti- Fair, G. M., Geyer, J. C., and Okun, D. A. Water and Wastewater
fication of Losses in a Water Network, International Journal Engineering, Vol. 1, Water Supply and Wastewater
of Water Resources Development, 7, 1, pp. 30–38, 1991. Removal, John Wiley & Sons, New York, 1966.
Department of Water Supply Web Site, County of Maui, Hawaii, National Resources Conservation Service, U.S. Department of
http://mauiwater.org/, 2010. Agriculture, Water Supply Forecasting, http://www.wcc.
Fair, G. M., Geyer, J. C., and Okun, D. A., Elements of Water nrcs.usda.gov/wsf/, 2009.
Supply and Wastewater Disposal, John Wiley & Sons, Orlob, G. T., and Lindorf, M. R., Cost of Water Treatment in
New York, 1971. California, J. Am. Water Works Assoc., 50, 45, 1958.