Note: This is documentation for version 4.11 of Source. For a different version of Source go to the Space Directory.
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The Percent Removal filter removes a fixed percentage of the constituent associated with the quick flow of the functional unit (FU) and a fixed percentage of the constituent associated with the baseflow.


This model is a catchment scale model.

Principal developer

Cooperative Research Centre for Catchment Hydrology


Source v4.3


Requires a constituent generation model to be assigned to the corresponding functional unit(s).


The Percent Removal filter is automatically installed with Source.

Flow phase

Each time-step, the model removes a fraction of the constituent load that was generated from the functional unit.

The constituent generation models generate both a ‘quick load’, associated with the quick flow component of runoff, and a ‘slow load’, associated with the slow flow, or baseflow, runoff component.

The quick load is reduced by the Percent Removal filter using the PercentRemovalQ parameter.


Equation 1

The same process is applied to the constituent load associated with the baseflow (the ‘Slow Load’ here), using a separate, PercentRemovalS parameter.

Equation 2

The result of the filter is the total load for the functional unit, which is the sum of the filtered quick load and the filtered slow load.

Equation 3

Input data

This model operates on the incoming constituent load, which is automatically provided to the model by Source.

Parameters or settings

Refer to Table 1.

Table 1. Parameters or settings






Slow Flow Percent Removal

A single, constant value (%) of load removed from the slow flow




Output data

The resulting filtered constituent load. These model results can be retrieved by recording the quick flow, slow flow or total flow outputs of the functional unit.