This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Hydrologic Channel Routing – Set 2”.
1. What is the value of the constant exponent in the channel storage equation to obtain Muskingum equation?
a) 0
b) 0.5
c) 0.6
d) 1
View Answer
Explanation: Substituting the value of constant exponent m = 1 in the channel storage equation, we get a linear relationship of storage S in terms of inflow I and outflow Q. This is known as Muskingum equation and is given as,
S=K[x.I+(1-x).Q]
2. What is the range of the weightage factor in Muskingum equation?
a) -1 to 1
b) -0.5 to 0.5
c) 0 to 0.5
d) 0 to 1
View Answer
Explanation: The weightage factor in Muskingum equation assigns the proportion to the inflow and outflow values. If the weight of inflow is x, the weight of outflow must be (1 – x). Therefore, the range of x is between 0 and 0.5.
3. When the weightage factor is Muskingum equation is zero, the storage depends on inflow only.
a) True
b) False
View Answer
Explanation: The weighting factor is multiplied with the inflow in Muskingum equation. If it is zero, the inflow term becomes zero and the weight of outflow is (1 – 0) = 1. Hence, the storage will depend on outflow only.
4. For what value of weightage factor in Muskingum equation does storage depend on inflow only?
a) 0
b) 0.5
c) 1
d) No such value
View Answer
Explanation: The storage in a channel reach cannot depend only on inflow as the prism storage, which is a function of outflow, always exists. From the equation, the value of weightage factor is 0 to 0.5, and for all these values storage depends either on outflow only or both inflow and outflow.
5. Which of the equations represents a linear reservoir? S = storage of reservoir, I = inflow into reservoir, Q = outflow from reservoir. a, b and K are constants.
a) S=KI
b) S=KQ
c) S=K(aI+bQ)
d) S=K(Ia+Qb)
View Answer
Explanation: When the weighting factor x in Muskingum equation is zero, the inflow term becomes zero and the storage depends on the outflow only. This condition when there is no wedge storage is known as linear reservoir. From Muskingum equation,
S=K[x.I+(1-x).Q]=K[0.I+(1-0).Q]=KQ
6. When the weighting factor in Muskingum equation has its highest value, which of the following is true for channel storage?
a) It depends on inflow only
b) It depends on outflow only
c) It depends on both inflow and outflow but not equally
d) It equally depends on both inflow and outflow
View Answer
Explanation: The maximum value of weighting factor is 0.5. Substituting x = 0.5 in Muskingum equation,
S=K[x.I+(1-x).Q]=K[0.5.I+(1-0.5).Q]=K(0.5I+0.5Q)
This implies that both inflow and outflow have equal weightages of 0.5.
7. Which of the following units represents the storage-time constant in Muskingum equation?
a) seconds
b) seconds-1
c) m3/s
d) Dimensionless
View Answer
Explanation: The storage-time constant in Muskingum equation has the units of time. This can be dimensionally computed from the Muskingum equation knowing that the storage has units of m3, inflow and outflow have units of m3/s and weighting factor is unitless.
8. Which of the following most closely represents the value of storage-time constant in channel routing?
a) Time taken by flood to travel the channel reach
b) Time represented by the peak lag
c) Time taken for the flood to cause both positive and negative wedge storage
d) Time taken to reach outflow peak
View Answer
Explanation: The storage-time constant in Muskingum equation is a quantity that represents time and is approximately equal to the time taken by a flood wave to travel through the channel section.
9. How is channel routing different from level pool routing in a channel with no lateral inflow?
a) The outflow peak occurs at the intersection of inflow and outflow hydrograph
b) No peak lag
c) The outflow peak occurs after the intersection of inflow and outflow hydrograph
d) No peak attenuation
View Answer
Explanation: Unlike level pool routing in which the peak of outflow hydrograph intersects the inflow hydrograph, in channel routing the peak of outflow occurs after their intersection. However, similar to level pool routing there is a lag in outflow peak, and it is attenuated.
10. Which of the following is a correct value of Muskingum weighting factor for a natural channel?
a) 0.25
b) 0.33
c) 0.45
d) 0.5
View Answer
Explanation: For a given channel, the weighting factor and storage-time constant do not change. Generally for natural channels, the value of weighting factor lies between 0 and 0.3.
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