The Muskingum method is a widely used hydrologic method for flood routing. This method models the storage in a river reach as a function of
- AThe elevation of the river only
- BThe inflow discharge only
- CThe outflow discharge only
- DA weighted combination of inflow and outflow dischargesCorrect
Solution
Concept
Muskingum channel flood routing storage relationship
Formula
S = K × [x × I + (1 - x) × Q]
Step-by-step solution
1. In the Muskingum flood routing method, reach storage comprises prism storage and wedge storage. 2. Prism storage is formed by a volume of constant cross section proportional to outflow Q. 3. Wedge storage is formed between inflow and outflow water profiles proportional to (I - Q). 4. Combining these gives storage as a linear weighted function of inflow and outflow: S = K[x·I + (1-x)·Q]. Answer: D
Explanation
The Muskingum flood routing method is a hydrologic routing technique for channels where storage in a river reach is modeled as a function of both prism storage (outflow-dependent) and wedge storage (inflow-outflow difference). The total reach storage is expressed as a weighted combination of inflow and outflow discharges: S = K[x·I + (1-x)·Q].
Why the other options are wrong
A) Reservoir stage-storage routing uses elevation, whereas Muskingum uses discharges. B) Inflow alone ignores wedge storage dissipation and translation. C) Linear reservoir routing depends only on outflow, not reach routing.
Shortcut
Muskingum storage = Prism (outflow) + Wedge (inflow - outflow) = Weighted I and Q.
Common mistake
Assuming Muskingum routing is a hydraulic routing method based on river stage elevation rather than hydrologic discharge routing.
Correct answer: D) A weighted combination of inflow and outflow discharges