Deck 14: Stormwater Detention

Question 1

The usual method for computing storage volume is the elevation-area method.

Answer 1

True

Question 2

The primary purpose of an emergency spillway is to control any eventual overtopping of the detention basin by directing the flow in a harmless direction.

Answer 2

False

Question 3

The ____________________ is the volume of water temporarily stored in a detention basin during a rainfall event.

Answer 3

impoundment

Question 4

A multiple-stage outlet contains more than one outlet structure.

Question 5

Separate grassed channels are used for major detention basins with large maximum impoundments because this is the safest type of emergency spillway.

Question 6

When runoff enters a detention basin and is temporarily stored and then exits through the outlet structure, the peak rate of outflow is____________________ the peak rate of inflow.

Question 7

What is the term for computing the outflow hydrograph when the inflow hydrograph is known?

A)attenuation
C)continuity
B)routing
D)Kinematic Wave Method

Question 8

A single-stage outlet is so called because it allows water to flow through ____ opening(s).

A)one
C)three
B)two
D)four

Question 9

Impounded water in a detention basin is released quickly through the outlet structure.

Question 10

Volume for underground detention basins is computed using which method?

A)elevation-area method
C)end-area elevation method
B)average end-area method
D)average method

Question 11

What is the calculation called for a series of hypothetical water levels in an impoundment and their corresponding discharge through an orifice?

A)single-stage outlet
C)discharge rating
B)impoundment
D)berm

Question 12

The Modified Puls Method method of reservoir routing relies on the so-called ____________________, which is a statement of conservation of the mass of water entering and leaving the reservoir or impoundment.

Question 13

A rainfall event that exceeds the design storm rainfall could ____.

A)drain out the main outlet
B)cause the impoundment level to exceed maximum elevation
C)damage the outlets
D)decrease the impoundment level

Question 14

Emergency spillways consist of an additional ____________________ set at an elevation higher than all others so that water will not enter unless the impoundment level has risen higher than anticipated for the design storm.

Question 15

The primary purpose of an emergency spillway is to provide a way for excessive water in the impoundment to exit safely, thus preventing a(n) ____________________ of the berm.