The links connecting source, treatment, and junction nodes may represent pipes, open channels, or natural watercourses. To enable more accurate simulation, the user may specify the routing properties of each link.
Routing Properties
You may specify No Routing or Storage (Muskingum) Routing for any link in a treatment train. If you specify no routing, you don't need any more input.
No Routing
All links are assigned No Routing by default and have the following features:
- Water enters and exits such a link in the same time step and
- There are no configuration parameters associated with No Routing links.
Storage (Muskingum) Routing
If you select Storage Muskingum Routing, enter appropriate values for the parameters k (storage constant in seconds), m (storage exponent), and x (inflow bias). Inflow bias measures the relative effect of inflow and outflow on the behavior in a reach. For more information, see Storage (Muskingum) Routing.
Lagged Flow Routing (Translation only)
Lagged flow routing only considers the average travel time of water in the link. It does not consider flow attenuation. The flow entering a link exits at multiple time-steps in the future. You can model lagged flow routing using Storage Routing as follows:
- Compute the number of divisions, n, by dividing the dividing average travel time by the model time-step and round the result to a whole number. The result must be at least one (ie. n ≥ 1);
- Configure a storage flow routing reach where:
- n = number of divisions;
- x = 1;
- m = 1; and
- k = model time-step.
- If you need to account for lateral flows where n = 1 and the average travel time is a fraction of the model time-step (eg. a reach with a one day lag in a model with a monthly time-step), you can adjust k to the smaller time step value without affecting the shape of the hydrograph. For stability K ≤ dt/x and in this case x = 1.
Outflow Components
The Outflow Components describes the outflow components represented by the Drainage Link. If using a 'Primary' drainage link, these outflow components cannot be altered. However, if using a 'Secondary' drainage link, the outflow components can be updated by checking or unchecking the appropriate tick box.