The Muskingum routing method ("Figure: Muskingum Routing Edit Panel") is a linear routing method that describes the routing with three parameters: Muskingum K, Muskingum X, and Number of Subreaches.
Figure: Muskingum Routing Edit Panel
The Muskingum method computes outflow from the reach using the following equation:
O_{t} = (A-B)*I_{t-1}+(1-A)*O_{t-1}+B*I_{t}
Where:
A=\frac{2*\Delta t}{2*K*(1-X)+\Delta t}
B=\frac{\Delta t - 2*K*X}{2*K*(1-X)+\Delta t}
and: O = Outflow I = Inflow t = the current timestep ∆t = the length of the timestep K = Muskingum K X = Muskingum X
Muskingum K—The travel time for the reach, in hours; i.e., how long it takes for a drop of water that enters the reach to exit the reach.
Muskingum X—The Muskingum weighting factor or attenuation coefficient, a value from 0.0 to 0.5. X= 0.0 indicates maximum attenuation of the hydrograph through the routing reach. X=0.5 indicates no attenuation; a "direct translation" of the hydrograph through the reach.
Number of Subreaches—The travel time through any reach should be at least as long as the timestep. If the travel time is greater than the timestep, the number of subreaches should approximately equal K/∆t. If the travel time of a reach is less than half the length of the timestep, consider using Null routing.
A Rule of Thumb…The Number of Subreaches should equal K/∆t (rounded to a whole number), where: K is the travel time and ∆t is the length of the timestep (in hours).
