| Table of Contents | ||
|---|---|---|
|
...
| Info | ||
|---|---|---|
| ||
Note:
|
...
Figure 2. Configure constituents
| Anchor | ||||
|---|---|---|---|---|
|
There are two types of constituent routing available, Lumped and Marker routing. (Figure 2) and the choice made here will affect how constituents are routed at a link. Both of these are conservative routing models, which means that they do not change the total mass of constituent in the system.
Lumped routing (default) is the simplest and most common approach applied in Source. Constituents are routed within a link based on kinematic wave theory. Assuming fully-mixed conditions within a link, the constituent flux and concentration simply move from the top of a link to the downstream end of a link within a time step, preserving the mass balance. Constituent concentrations in a link can be altered by the addition of constituents generated from sub-catchments, external inflows, and losses defined within a reach; and
- Marker routing considers constituents as particles and tracks their movement within a link, which can be divided into divisions for hydrologic routing purposes. While available to all users this method is less commonly used. Initially, the model will start with a marker at the end of each division in every link. At every time step, a new marker for each constituent will be created for each division, and the distance a marker moves is driven by the velocity in the division over the current time step. While the flow rate is assumed constant over the timestep, the velocity within the division will change as a result of a change in reach storage. Markers will travel through the river network until they are either merged with adjoining markers or leave the river network (iei.e. via extractions, decay within the reach, evaporation, groundwater inflows/losses and rainfall). Although available to all users, this method is less commonly used. Refer to Marker routing (Particle tracking) - SRG for more information about Marker routing.
For marker routing, you must specify two additional parameters:- Minimum Marker Gap – defines the spacing between markers as either a fraction of the model time-step or fraction of the reach division. This parameter can improve model efficiency by reducing the number of markers that require processing at each model time step. The allowable range is from 0 to 1, with 0 not deleting any markers, while a value of 1 will ensure that at the end of each time-step, there is only one marker defined for each reach division; and
- Minimum volume – minimum volume required to maintain constituent mass balance within the links.
...
Refer to Working with rainfall-runoff models for more details on assigning a constituent model, adding input data and changing parameters. For more information on using filters see Working with filters in the Feature Table. There is also a sub-catchment filter to help you find sub-catchments either by name or by using the sub-catchment map, see Sub-catchment filter.
...
Figure 3. Constituent Model Configuration
| Anchor | ||||
|---|---|---|---|---|
|
...