Practice Test Geeks(CFS) Certified Floodplain Surveyor Practice Test
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Hydrologic & Hydraulic Analysis Flashcards

7 cards from real CFS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Hydrologic & Hydraulic Analysis flashcards as text

  1. A surveyor observes that a bridge creates a Class A (low chord) profile in HEC-RAS. This means the bridge is operating under which condition?

    Answer: The water surface passes below the low chord with no bridge submergence

    A Class A profile in HEC-RAS means water surface remains below the low chord of the bridge, so the bridge operates without pressure or weir flow complications.

  2. The unit hydrograph theory assumes which fundamental relationship between rainfall excess and runoff?

    Answer: Linearity and time-invariance: doubling rainfall excess doubles the hydrograph ordinates

    Unit hydrograph theory is based on the principle of linearity (proportionality) and superposition—runoff response is directly proportional to the rainfall excess depth.

  3. In floodplain modeling, what is the significance of the 'energy grade line' (EGL)?

    Answer: It represents the total energy head (velocity head + pressure head + elevation) at each cross-section

    The energy grade line represents the total specific energy (elevation + pressure head + velocity head) and slopes downward in the direction of flow due to friction losses.

  4. For an NFIP flood study, FEMA requires that base flood discharges be determined using which recurrence interval?

    Answer: 100-year (1% annual chance)

    FEMA defines the Base Flood as the 1-percent-annual-chance (100-year) flood event, which is the regulatory standard for the NFIP.

  5. Channel improvement projects that increase flow velocity can affect downstream areas by:

    Answer: Increasing peak discharge and advancing the flood hydrograph timing downstream

    Channelization moves water faster through the improved reach, which can increase peak discharge and cause earlier, higher flood peaks downstream.

  6. The SCS dimensionless unit hydrograph has a peak discharge that occurs at what fraction of the time to peak (Tp)?

    Answer: 1.0 Tp

    By definition, the SCS dimensionless unit hydrograph reaches its peak at exactly 1.0 Tp (the time to peak), then recedes symmetrically.

  7. When applying the Manning's equation in English units, what is the value of the conversion factor used?

    Answer: 1.486

    Manning's equation in English (CFS) units is Q = (1.486/n)AR^(2/3)S^(1/2), where 1.486 converts from SI metric units to English units.