Water Resources and Environmental Engineering — Quiz 1

Questions in this quiz (10)

1. A commercial area has a drainage basin of $$25\ \mathrm{acres}$$ with a runoff coefficient of $$0.65$$. During a storm event, the rainfall intensity is measured at $$4.5\ \mathrm{in/hr}$$. Using the Rational Method, determine the peak runoff rate from this drainage area.

   • $$73.1\ \mathrm{cfs}$$
   • $$112.5\ \mathrm{cfs}$$
   • $$58.5\ \mathrm{cfs}$$
   • $$48.8\ \mathrm{cfs}$$

2. Water flows through a concrete-lined trapezoidal channel with a Manning's roughness coefficient of $$0.013$$. The hydraulic radius is $$1.2\ \mathrm{m}$$ and the channel slope is $$0.002\ \mathrm{m/m}$$. Using Manning's equation, calculate the flow velocity.

   • $$2.94\ \mathrm{m/s}$$
   • $$4.85\ \mathrm{m/s}$$
   • $$3.88\ \mathrm{m/s}$$
   • $$3.12\ \mathrm{m/s}$$

3. Water flows through a pipe system. At point 1, the pressure is $$350\ \mathrm{kPa}$$, velocity is $$2.0\ \mathrm{m/s}$$, and elevation is $$5.0\ \mathrm{m}$$. At point 2, the velocity is $$4.0\ \mathrm{m/s}$$ and elevation is $$2.0\ \mathrm{m}$$. Assuming no head losses and using $$\gamma=9.81\ \mathrm{kN/m^3}$$, determine the pressure at point 2.

   • $$379.4\ \mathrm{kPa}$$
   • $$350.0\ \mathrm{kPa}$$
   • $$336.1\ \mathrm{kPa}$$
   • $$373.4\ \mathrm{kPa}$$

4. An unconfined aquifer has a hydraulic conductivity of $$15\ \mathrm{m/day}$$. Groundwater flows through a cross-sectional area of $$50\ \mathrm{m^2}$$ over a distance of $$200\ \mathrm{m}$$ with a head difference of $$3.5\ \mathrm{m}$$. Using Darcy's Law, calculate the groundwater flow rate.

   • $$26.3\ \mathrm{m^3/day}$$
   • $$13.1\ \mathrm{m^3/day}$$
   • $$5.25\ \mathrm{m^3/day}$$
   • $$52.5\ \mathrm{m^3/day}$$

5. A $$5$$-in precipitation falls on a $$300$$-ft wide and $$400$$-ft long open field in $$24$$ hours. The drainage area has a curve number of $$60$$. The run-off volume expected from the event, in $$\mathrm{ft^3}$$, is most nearly:

   • $$50000\ \mathrm{ft^3}$$
   • $$30000\ \mathrm{ft^3}$$
   • $$13000\ \mathrm{ft^3}$$
   • $$3000\ \mathrm{ft^3}$$

6. An urban watershed area consists of four types of surfaces: Asphalt pavement: $$24$$ acres, $$C=0.73$$ Concrete pavement: $$16$$ acres, $$C=0.85$$ Lawns (heavy soil): $$35$$ acres, $$C=0.22$$ Roofs: $$25$$ acres, $$C=0.90$$ Determine the composite run-off coefficient of the area.

   • $$2.7$$
   • $$0.9$$
   • $$0.7$$
   • $$0.6$$

7. The curve number $$CN$$ in the NRCS rainfall-runoff method depends on which of the following?

   • $$\text{Land cover, soil and hydrologic soil group}$$
   • $$\text{24-hour rainfall}$$
   • $$\text{100-year storm}$$
   • $$\text{Initial abstraction of the drainage area}$$

8. The NRCS Rainfall-runoff method assumes that the initial abstraction, including depression storage, evaporation, and interception losses, is most nearly:

   • $$0.00$$
   • $$10\%\ \text{of the maximum basin storage or retention capacity}$$
   • $$20\%\ \text{of the maximum basin storage or retention capacity}$$
   • $$80\%\ \text{of the maximum basin storage or retention capacity}$$

9. Which of the following is an INCORRECT statement regarding a unit hydrograph?

   • $$\text{A unit hydrograph represents 1 inch (or 1 mm) of direct runoff from one unit of effective rainfall occurring uniformly in space over a unit period of time.}$$
   • $$\text{The unit hydrographs can be superimposed, and linearity of the relation applies.}$$
   • $$\text{A unit hydrograph reflects all features of the watershed basin.}$$
   • $$\text{By using a unit hydrograph, the properties of a watershed basin can be altered.}$$

10. A combined sewer system serves a drainage area of $$50\ \mathrm{hectares}$$. A CSO storage facility is designed to capture the first $$6\ \mathrm{mm}$$ of runoff. Calculate the required capture volume.

    • $$300\ \mathrm{m^3}$$
    • $$3000\ \mathrm{m^3}$$
    • $$30000\ \mathrm{m^3}$$
    • $$1500\ \mathrm{m^3}$$