The Export Rate model applies a fixed constituent generation rate to a functional unit (FU) to calculate total constituent load. It requires only a single parameter so is quick to use and therefore useful for exploring sensitivity.
Scale
This model is applied at the functional unit scale within a sub-catchment.
The model is a scaling factor and is independent of the basic time-step of the model. It is therefore more appropriate for estimating long term loads.
Principal developer
Cooperative Research Centre for Catchment Hydrology.
Version
Source v2.10
Availability/conditions
Export Rate is automatically installed with Source.
Flow phase
The Export Rate model is a simple area-based scaling factor for constituents from a functional unit. It defines a value between 0 and ∞, representing the physical amount of constituent exported per unit area per year.
For constituent C
| Equation 318 |
Input data
A single value representing the export rate in units of tonne/ha/year is required. Area of the FU is taken from the model.
For export rates: |
...
Generic lookup tables of export rates are available but there can be large variability
between areas, which can introduce considerable uncertainty (Fletcher et al, 2004).
Long-term data is required to derive reliable local values.
...
Parameters or settings
The parameters for this model are summarised in Table 72.
Output data
Constituent load in kg per time-step.
References
Fletcher, T, Duncan, H, Poelsma, P & Lloyd, L 2004, Stormwater flow and quality, and the effectiveness of non-proprietary stormwater treatment measures - a review & gap analysis, Technical Report 04/8, Cooperative Research Centre for Catchment Hydrology.
Table 72. Model parameters
Parameter | Description | Units | Default Min | Default Max |
|---|---|---|---|---|
exportRate | Fixed rate of export of a constituent from a land use | tonne/ha/year | 0 | ∞ |