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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. In the Rational Method, what does the runoff coefficient 'C' represent?

    Answer: The ratio of peak runoff rate to rainfall intensity

    The runoff coefficient C is a dimensionless ratio representing the fraction of rainfall that becomes direct runoff, ranging from 0 to 1.

  2. Which hydraulic assumption underlies the HEC-RAS steady-state water surface profile computation?

    Answer: The energy equation is applied between successive cross-sections assuming gradually varied flow

    HEC-RAS steady-state profiles solve the energy equation (standard step method) between cross-sections under the gradually varied flow assumption.

  3. What is the primary purpose of a stage-discharge rating curve?

    Answer: To relate water surface elevation to flow rate at a specific channel location

    A rating curve defines the relationship between stream stage (water surface elevation) and discharge at a gauging station, enabling flow estimates from stage readings.

  4. The TR-55 graphical peak discharge method is most appropriately applied to watersheds with drainage areas up to:

    Answer: 20 square miles

    TR-55 is intended for small watersheds up to approximately 20 square miles where simplified hydrologic assumptions are reasonable.

  5. In open channel hydraulics, critical flow occurs when the Froude number equals:

    Answer: 1.0

    Critical flow is defined as the condition where the Froude number equals 1.0, representing the transition between subcritical and supercritical flow.

  6. When performing a backwater analysis in HEC-RAS for a subcritical flow regime, computations proceed in which direction?

    Answer: Downstream to upstream

    Subcritical flow profiles are computed from downstream to upstream because downstream boundary conditions control the water surface elevation.

  7. Which hydrologic loss method in HEC-HMS uses antecedent moisture condition (AMC) to adjust curve numbers?

    Answer: SCS Curve Number method

    The SCS Curve Number method adjusts CN values based on AMC-I (dry), AMC-II (average), and AMC-III (wet) antecedent soil moisture conditions.