The direct page on the Inflows Editor page is used to specify the time history of direct
external flow and water quality entering a node of the drainage system. These inflows are
represented by both a constant and time varying component as follows:
inflow at time t = (baseline value)*(baseline pattern factor) +
(scale factor) * (time series value at time t)
The page contains the following input fields that define the properties of this relation:
| Field | Description |
| Constituent | Selects the constituent (FLOW or one of the project's named pollutants) whose direct inflow will be described. |
| Baseline | Specifies the value of the constant baseline component of the constituent's inflow. For FLOW, the units are the project's flow units. For pollutants, the units are the pollutant's concentration units if inflow is a concentration, or can be any mass flow units if the inflow is a mass flow (see Units Factor below). If left blank then no baseline inflow is assumed. |
| Baseline Pattern | An optional Time Pattern whose factors adjust the baseline inflow on either an hourly, daily, or monthly basis (depending on the type of time pattern specified). Clicking the EditBtn button will bring up the Time Pattern Editor dialog for the selected time pattern. If left blank, then no adjustment is made to the baseline inflow. |
| Time Series | The name of the time series that describes the time varying component of the constituent's inflow. If left blank then no time varying inflow is assumed. Clicking the EditBtn button will bring up the Time Series Editor dialog for the selected time series. The units of the time series values obey the same convention as described above for Baseline inflow. |
| Scale Factor | A multiplier used to adjust the values of the constituent's inflow time series. The baseline value is not adjusted by this factor. The scale factor can have several uses, such as allowing one to easily change the magnitude of an inflow hydrograph while keeping its shape the same, without having to re-edit the entries in the hydrograph's time series. Or it can allow a group of nodes sharing the same time series to have their inflows behave in a time-synchronized fashion while letting their individual magnitudes be different. If left blank the scale factor defaults to 1.0. |
| Inflow Type | For pollutants, this field selects the type of inflow data as being either a CONCENTRATION (mass/volume) or a MASS FLOW RATE (mass/time). This field does not appear for FLOW inflow. |
| Units Factor | A numerical factor used to convert the units of pollutant mass flow rate into concentration mass units per second. For example, if the inflow data were in lbs/day and the pollutant concentration was chosen as mg/L, then the conversion factor value would be (453,590 mg/lb) / (86,400 sec/day) = 5.25 (mg/sec) per (lb/day). This field does not appear for FLOW inflow, and for concentration-type inflows any value entered will be overriden to 1.0. |
More than one constituent can be edited while the dialog is active by simply selecting another choice for
the Constituent property. However, if the Cancel button is clicked then any changes made to all
constituents will be ignored.
If a pollutant is assigned a direct inflow in terms of concentration, then one must also assign a
time series inflow to flow, otherwise no pollutant inflow will occur. An exception is at submerged
outfalls where pollutant intrusion can occur during periods of reverse flow. If pollutant inflow is
defined in terms of mass, then a corresponding flow inflow is not required.