Water Resources and Environmental Engineering — Quiz 9

Questions in this quiz (10)

1. A $$5$$-ft inner diameter concrete storm drain carries $$300\ \mathrm{ft^3/s}$$. The Manning's coefficient for the drain pipe is $$0.013$$. For a design depth of $$4$$ ft, the minimum slope for the pipe line is most nearly:

   • 0.004
   • 0.014
   • 0.4
   • 1.4

2. An aquifer has a hydraulic conductivity of $$6.2\ \mathrm{m/day}$$ and a saturated thickness of $$18\ \mathrm{m}$$. Calculate the transmissivity of the aquifer.

   • 111.6 m^2/day
   • 96.2 m^2/day
   • 124.5 m^2/day
   • 72.8 m^2/day

3. A trapezoidal channel has a wetted perimeter of $$3.5$$ m with concrete lining $$\left(n=0.014\right)$$ and $$5.5$$ m with grass lining $$\left(n=0.032\right)$$. Using the linear weighted method, calculate the composite Manning's $$n$$.

   • 0.0245
   • 0.0208
   • 0.0261
   • 0.0189

4. A pump must transfer water from a reservoir at elevation $$12$$ m to a tank at elevation $$48$$ m. The friction head loss is $$7.2$$ m and minor losses total $$1.8$$ m. Calculate the total pump head required.

   • 44.0 m
   • 45.8 m
   • 37.8 m
   • 49.0 m

5. A rectangular weir with a crest length of $$3.2$$ m passes a measured discharge of $$2.2\ \mathrm{m^3/s}$$ when the head over the weir is $$0.48$$ m. Calculate the weir discharge coefficient $$C$$.

   • 1.63
   • 1.38
   • 1.82
   • 1.47

6. While using the Darcy-Weisbach equation for estimating head loss in a pipe flow, the friction factor was misjudged by $$+20\%$$. For this case, the error in estimating discharge is:

   • +10%
   • +40%
   • -40%
   • -10%

7. Which statement is true about hydraulic pumps?

   • The discharge of two pumps in series is more than one pump operating alone.
   • The pump performs at peak when it reaches its maximum operating head.
   • Cavitation can occur when the available head is more than the head required for satisfactory operation.
   • Water hammer and surge are synonymous terms.

8. Water is to be pumped at a flowrate of $$0.244\ \mathrm{m^3/s}$$ from reservoir $$A$$ to reservoir $$B$$. The water surface elevation in reservoir $$A$$ is $$150\ \mathrm{m}$$ and in reservoir $$B$$ is $$200\ \mathrm{m}$$. The pipe has length $$300\ \mathrm{m}$$, diameter $$200\ \mathrm{mm}$$, and friction factor $$f=0.003$$. Ignoring minor losses, determine the required pump head.

   • 85.45
   • 63.85
   • 51.78
   • 25.36

9. The pump shown operates at efficiency of $$85\%$$. The suction line is $$12$$ in. in diameter and $$500$$ ft long. The discharge line is $$8$$ in. in diameter and $$2200$$ ft long. Water is pumped at $$1200$$ gpm. Both pipes are cast iron, and minor losses total $$15$$ ft of headloss. The lower reservoir water surface elevation is $$320$$ ft and the upper reservoir water surface elevation is $$540$$ ft. Determine the required pump power rating.

   • 106 hp
   • 232 hp
   • 116 hp
   • 202 hp

10. A circular conduit of diameter $$600\ \mathrm{mm}$$ has Manning's $$n=0.015$$ and longitudinal slope $$S=1\%$$. Normal depth of flow occurs at a depth of $$240\ \mathrm{mm}$$. Determine the flow rate.

    • 0.2333 m^3/s
    • 0.3781 m^3/s
    • 0.0701 m^3/s
    • 0.1793 m^3/s