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Processes that act on these constituents to generate and transport them can be modelled in Source and are broadly categorised as Catchment Water Quality Quality models and Storage and Link Water Quality models.
Catchment water quality models include:
- Constituent generation models - describe how constituents are generated within a functional unit (and any associated constituent sources) and the resulting concentrations or loads are delivered to the sub-catchment link
- Constituent filtering models - represent any reduction in constituents between generation within the FU and arrival at the link upstream of the sub-catchment link.
Storage and link water quality models include:
- Constituent routing models - describe the movement of constituents along a river channel network, including exchange of constituent fluxes between floodplains, wetlands, irrigation areas and groundwater. Constituent routing models are conservative, meaning that they do not alter the total mass of constituent stored in the system
- Constituent processing models - describe processes that can alter the mass of a constituent in a storage or river reach (link), such as via a decay process.
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Before using this dialog, you need to define constituents and constituent sources (as described in Defining constituents) and also either set up your catchment area using the Geographic Wizard for catchments and assigned FU areas and/or add constituents to nodes or links Then, you can use the tree menu on the left to view the filter and generation models for each sub-catchment/FU combination, the instream processing model for each storage routing link, and the storage processing model for each storage node.
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- Change the assigned model,
- Change the parameter values or input data for the assigned model,
- Filter columns based on their contents
- Sort columns in ascending or descending order; and
- For filter and generation models you can also change, add or remove constituent sources, see Configuring constituent sources.
Refer to Working with rainfall-runoff modelswith 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
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Along with flows, constituents are also transferred when using a Scenario Transfer node.
Constituents and Ownership
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Linking constituent generation or filter models
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Note: This functionality is currently under development and not all models can be linked. The description that follows is an illustration of what can be undertaken in Source. |
Constituent generation and filter models may require one or more of their parameters to originate from another generation or filter model. Source allows a constituent NDR filter model to contain parameters which depend on a parameter from another generation / filter model. The concept is similar to that of functions whereby a parameter can be set from elsewhere in the system. Functions cannot be used here because the function manager is unable to influence the running order of models in a functional unit. So instead the design has a simple parameter linking tool which allows a user to connect one parameter on one constituent model to another parameter on another. The model parameter which is to be written to must have been compiled with metadata indicating that its value should come from another constituent model’s parameter. The function described above is termed as “Define Constituent Model Linkage” in Source.
Not all models can be linked. The description that follows is an illustration of what can be undertaken in the current version of Source, where nutrient delivery to the NDR filter model can be configured to depend on, for example, available sediment derived from another filter model (typically the SDR filter model) or one of the configured constituent generation models for a particular FU/sub-catchment combination
To configure constituent model linking between models for a given sub-catchment/FU combination and an optional constituent source, assign an NDR model to the “receiving” constituent, as shown in Figure 15. In this example TN is considered the “receiving” constituent. Although other filter models have been applied, only the NDR model has an active button where a link to another modelled constituent can be defined. The link is defined in the quickflowSedimentIn column. TSS, in this example, is the “contributing” constituent. Constituents derived through a Generation model and a Filter model are available for TSS. The user selects a contributing model and associated parameter which will provide the “contributing” constituent. In this example a linkage is defined between the SDR quickflowConstistuentIn parameter and the quickflowSedimentIn parameters of the NDR model (Figure 16). Once the linkage is created, the “contributing” model (in this case an SDR model) is run before the NDR (“receiving”) model, allowing the correct flow of data at the right point in time.
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