CPESC Hydrology & Hydraulics 2

Question 1

What is the hydraulic radius of a channel cross-section, and how is it calculated?

Accepted Answer

The ratio of flow area to wetted perimeter; A/P

Answer

The average depth of flow; calculated as total depth divided by 2

Answer

The width of the water surface; top width of flow

Answer

The maximum depth of flow in the channel cross-section

Question 2

A 2-year, 24-hour storm event is commonly used for which type of erosion and sediment control design?

Accepted Answer

Designing temporary diversion channels and sediment basins during construction

Answer

Sizing permanent retention ponds for post-construction

Answer

Computing 100-year floodplain boundaries

Answer

Determining TMDL allocations for receiving streams

Question 3

In stormwater hydrology, the term 'imperviousness' refers to:

Accepted Answer

The percentage of a watershed surface that does not allow water infiltration

Answer

The ability of soil to resist compaction under load

Answer

The depth of soil available for root zone water storage

Answer

The rate at which sediment accumulates in a basin

Question 4

Which flow regime is considered most erosive and is characterized by a Froude number greater than 1.0?

Accepted Answer

Supercritical (rapid) flow

Answer

Subcritical (tranquil) flow

Answer

Laminar flow

Answer

Transitional flow

Question 5

The unit peak discharge (qu) used in the TR-55 graphical peak discharge method is expressed in units of:

Accepted Answer

Cubic feet per second per inch of runoff per square mile (csm/in)

Answer

Cubic feet per second per acre (cfs/acre)

Answer

Gallons per minute per impervious acre

Answer

Acre-feet per hour

Question 6

Detention storage in stormwater management is designed primarily to:

Accepted Answer

Temporarily store runoff to reduce peak discharge rates to pre-development levels

Answer

Permanently retain all runoff on-site to prevent any discharge

Answer

Filter sediment from runoff through a gravel media

Answer

Promote groundwater recharge through infiltration

Question 7

Sheet flow, shallow concentrated flow, and channel flow are the three flow regimes used in calculating time of concentration. Which typically has the longest travel time per unit length?

Accepted Answer

Sheet flow across vegetated overland surfaces

Answer

Channel flow through a well-defined stream

Answer

Shallow concentrated flow over paved surfaces

Answer

Pipe flow in a storm drain system