CFM CFM Hydrology & Hydraulics 3

Question 1

A Detailed Flood Insurance Study uses the term 'Q100' to refer to:

Accepted Answer

The peak discharge of the 1% annual chance flood

Answer

Q100 denotes the peak streamflow discharge associated with the 1% annual chance (100-year) flood event, used as input into hydraulic models to compute BFE.

Question 2

Which soil hydrologic group has the highest runoff potential in the SCS method?

Accepted Answer

Group D

Answer

Hydrologic Soil Group D includes soils with very slow infiltration rates (e.g., heavy clays), resulting in the highest runoff potential when wetted.

Question 3

What is the purpose of a 'starting water surface elevation' (tailwater) in a HEC-RAS steady-flow analysis?

Accepted Answer

To define the downstream boundary condition from which water surface profiles are computed upstream

Answer

In subcritical (low-energy) flow analysis, HEC-RAS computes water surface profiles from downstream to upstream, requiring a known tailwater elevation as the starting boundary condition.

Question 4

Which of the following is the correct interpretation of a 26% probability of flooding over a 30-year mortgage period?

Accepted Answer

Approximately equivalent to a 1% annual chance flood over 30 years

Answer

A structure in the 1% annual chance floodplain has approximately a 26% cumulative probability of flooding at least once during a 30-year mortgage term.

Question 5

What is the primary distinction between a 'riverine' flood and a 'coastal' flood in NFIP mapping?

Accepted Answer

Riverine flooding is driven by overbank discharge from streams; coastal flooding includes tidal surge and wave action

Answer

Riverine flooding results from excess streamflow overtopping banks, while coastal flooding is caused by storm surge, tidal action, and wave energy from the ocean or large lakes.

CFM - Certified Floodplain Manager Practice Test

CFM - Certified Floodplain Manager Practice Test

CFM CFM Hydrology & Hydraulics 3