Civil Engineering PE Environmental Engineering and Stormwater Management 1

Question 1

In the rational method Q = CiA, the variable i represents:

Accepted Answer

Rainfall intensity for a storm duration equal to the time of concentration

Answer

Infiltration rate in inches per hour

Answer

Impervious fraction of the watershed

Answer

Inflow rate from upstream drainage

Question 2

The NRCS Curve Number (CN) method estimates:

Accepted Answer

Direct runoff depth from storm rainfall depth

Answer

Peak discharge rate only

Answer

Evapotranspiration losses only

Answer

Groundwater recharge volume

Question 3

Time of concentration (Tc) for a watershed is defined as:

Accepted Answer

Travel time from the hydraulically most remote point to the outlet

Answer

Time from start of rainfall to peak runoff at the outlet

Answer

Duration of the design storm event

Answer

Time required to fill the detention basin to the overflow elevation

Question 4

A dry detention basin is designed primarily to:

Accepted Answer

Attenuate peak flows by temporarily storing runoff

Answer

Permanently store stormwater for irrigation reuse

Answer

Remove dissolved pollutants through biological treatment

Answer

Recharge groundwater through infiltration only

Question 5

A typical Manning's roughness coefficient (n) for a natural earthen channel is:

Accepted Answer

0.025–0.035

Answer

0.010–0.013

Answer

0.050–0.080

Answer

0.100–0.150

Question 6

Hydraulic radius R in Manning's equation is defined as:

Accepted Answer

Cross-sectional flow area divided by wetted perimeter

Answer

Half the pipe diameter

Answer

Wetted perimeter divided by cross-sectional area

Answer

The depth of flow for wide channels