Water Resources and Environmental Engineering — Quiz 3

Questions in this quiz (10)

1. A residential development is composed of open space, residential area, and impervious area with the following curve numbers: Open space: $$2.5$$ acres, $$CN=74$$ Residential: $$8.5$$ acres, $$CN=80$$ Impervious: $$1.5$$ acres, $$CN=98$$ For a storm producing $$7$$ inches of rainfall, determine the runoff depth.

   • $$4.8\ \mathrm{inches}$$
   • $$5.1\ \mathrm{inches}$$
   • $$5.7\ \mathrm{inches}$$
   • $$7.0\ \mathrm{inches}$$

2. A concrete-lined trapezoidal channel is used to convey water flow between Point A at a surface elevation of $$510\ \mathrm{m}$$ and Point B at a surface elevation of $$508\ \mathrm{m}$$ over a distance of $$2$$ kilometers. The surface roughness coefficient of the concrete is $$0.012$$. The flow conveyed by this channel in $$\mathrm{m^3/s}$$ is most nearly. The channel has a bottom width of $$5\ \mathrm{m}$$, water depth of $$3\ \mathrm{m}$$, and side slopes corresponding to a horizontal projection of $$4\ \mathrm{m}$$ on each side.

   • $$70\ \mathrm{m^3/s}$$
   • $$105\ \mathrm{m^3/s}$$
   • $$150\ \mathrm{m^3/s}$$
   • $$165\ \mathrm{m^3/s}$$

3. An $$8$$-foot wide rectangular channel carries $$200$$ cubic feet per second of water at a depth of $$1.5$$ feet before entering a hydraulic jump. The water depth downstream of the jump is most nearly.

   • $$2.4\ \mathrm{ft}$$
   • $$2.7\ \mathrm{ft}$$
   • $$3.4\ \mathrm{ft}$$
   • $$4.4\ \mathrm{ft}$$

4. A pump is used to lift water from a reservoir with a surface elevation of $$210$$ feet to an outlet elevation of $$235$$ feet with discharge pressure of $$50$$ psi. The pump flow is $$100$$ gallons per minute and uses a $$2.5$$-inch diameter hose with a $$C$$ value of $$135$$. The distance from the pump to the outlet is $$200$$ feet. Head loss due to fittings is approximately $$5$$ feet. Determine the required pump pressure.

   • $$20\ \mathrm{psi}$$
   • $$40\ \mathrm{psi}$$
   • $$50\ \mathrm{psi}$$
   • $$70\ \mathrm{psi}$$

5. Which of the following statements is true of viscosity?

   • $$\text{It is the ratio of inertial to viscous force.}$$
   • $$\text{It always has a large effect on the value of the friction factor.}$$
   • $$\text{It is the ratio of the shear stress to the rate of shear deformation.}$$
   • $$\text{It is usually low when turbulent forces predominate.}$$

6. A horizontal jet of water with density $$1000\ \mathrm{kg/m^3}$$ is deflected perpendicularly to the original jet stream by a plate. The jet area is $$0.01\ \mathrm{m^2}$$ and the jet speed is $$30\ \mathrm{m/s}$$. The magnitude of force required to hold the plate in place is most nearly.

   • $$4.5\ \mathrm{kN}$$
   • $$9.0\ \mathrm{kN}$$
   • $$45.0\ \mathrm{kN}$$
   • $$90.0\ \mathrm{kN}$$

7. A stormwater system is designed for a $$25$$-year return period flood. What is the probability that this design flood will be exceeded at least once during a $$20$$-year project life?

   • $$55.8\%$$
   • $$44.6\%$$
   • $$36.0\%$$
   • $$28.4\%$$

8. A water treatment plant's filtration system receives water with a turbidity of $$38$$ NTU and produces filtered water with a turbidity of $$1.2$$ NTU. Calculate the turbidity removal efficiency.

   • $$96.8\%$$
   • $$95.2\%$$
   • $$93.7\%$$
   • $$97.4\%$$

9. At a point in a pipeline, the pressure is $$180\ \mathrm{kPa}$$, the elevation is $$18\ \mathrm{m}$$ above datum, and the flow velocity is $$2.5\ \mathrm{m/s}$$. Using $$\gamma=9.81\ \mathrm{kN/m^3}$$ and $$g=9.81\ \mathrm{m/s^2}$$, calculate the elevation of the Energy Grade Line.

   • $$37.8\ \mathrm{m}$$
   • $$36.4\ \mathrm{m}$$
   • $$35.8\ \mathrm{m}$$
   • $$39.1\ \mathrm{m}$$

10. A pumping well fully penetrates an unconfined aquifer with an initial saturated thickness of $$30$$ m. The well pumps at $$0.025\ \mathrm{m^3/s}$$, the hydraulic conductivity is $$18\ \mathrm{m/day}$$, and the radius of influence is $$450$$ m. Using the Dupuit equation, calculate the drawdown at a distance of $$120$$ m from the well.

    • $$1.12\ \mathrm{m}$$
    • $$0.84\ \mathrm{m}$$
    • $$1.46\ \mathrm{m}$$
    • $$0.62\ \mathrm{m}$$