VOSWMM

Land use

Click the Land Use button to open the Land Use Editor window.

Button Description
Add one land use
Delete selected land use. Please note to use Ctrl and Shift keys for multiple selection.
Import a group of land use
Export all the land use

General

  1. Land Use Name: This is the name assigned to the land use category, which serves as its identifier in the model.
  2. Description: An optional field where you can provide a comment or description of the land use. You can edit this field by clicking the ellipsis button or pressing Enter.
  3. Street Sweeping Interval: Specifies the number of days between street sweeping activities within the land use. Use “0” if there is no scheduled sweeping for this land use.
  4. Street Sweeping Availability: Represents the fraction of pollutant buildup within this land use that is available for removal by street sweeping.
  5. Last Swept: Indicates the number of days that have passed since the streets within this land use were last swept at the beginning of the simulation.

If street sweeping is not applicable to this particular land use, you can leave the last three properties (Street Sweeping Interval, Street Sweeping Availability, and Last Swept) blank.

Buildup

1. Function: This property defines the type of buildup function to be used for the pollutant. Options include:
• NONE: No buildup occurs.
• POW: Power function buildup.
• EXP: Exponential function buildup.
• SAT: Saturation function buildup.
• EXT: Buildup supplied by an external time series. The specific function is explained further in the “Pollutant Buildup” topic.
2. Max. Buildup: Specifies the maximum buildup that can occur for the pollutant, expressed in pounds (or kilograms) per unit of the normalizer variable. This value corresponds to the C1 coefficient used in the buildup formulas for pollutant buildup.
For the POW, EXP, and SAT buildup functions:
3. Rate Constant: Represents the time constant governing the rate of pollutant buildup. Units differ depending on the function:
• Power function: Mass per day raised to a power.
• Exponential function: 1/days.
4. Power/Sat. Constant: Applicable to both the Power and Saturation buildup functions:
• Power function: Represents the exponent C3 in the Power buildup formula.
• Saturation function: Corresponds to the half-saturation constant C2 in the Saturation buildup formula.
For the EXT (External Time Series) option:
5. Scaling Factor: A multiplier used to adjust the buildup rates specified in the time series.
6. Time Series: Refers to the name of the Time Series containing buildup rates (expressed as mass per normalizer per day).
7. Normalizer: Specifies the variable to which buildup is normalized on a per-unit basis. Choices include land area (in acres or hectares) or curb length, with consistent units across all subcatchments in the project.

When dealing with multiple pollutants, each pollutant must be selected separately from the Pollutant dropdown list, and its corresponding buildup properties should be defined accordingly.

Washoff

1. Pollutant: This field specifies the name of the pollutant for which the washoff properties are being defined.
2. Function: Defines the type of washoff function to be used for the pollutant. Options include:
• NONE: No washoff occurs.
• EXP: Exponential washoff.
• RC: Rating curve washoff.
• EMC: Event-mean concentration washoff. The specific formulas for each function are detailed in the “Pollutant Washoff” topic.
3. Coefficient: This value corresponds to C1 in the exponential and rating curve washoff formulas, or it represents the event-mean concentration, depending on the selected washoff function.
4. Exponent: Applicable to exponential and rating curve washoff functions. It specifies the exponent used in these washoff formulas.
5. Cleaning Efficiency: Indicates the street cleaning removal efficiency (in percentage) for the pollutant. It represents the fraction of the available removal amount on the land use as a whole (configured on the General page) that is actually removed.
6. BMP Efficiency: Denotes the removal efficiency (in percentage) associated with any implemented Best Management Practice (BMP). The washoff load calculated at each time step is reduced by this percentage.

To configure washoff properties for multiple pollutants, each pollutant must be selected individually from the Pollutant dropdown list, and its corresponding washoff properties should be specified accordingly.