SWMM - Time Pattern

Time Patterns allow the external dry weather flow (DWF) to vary periodically. They consist of a set of adjustment factors applied as multipliers to a baseline DWF flow rate or pollutant concentration. The different types of time patterns include:

• Monthly - A monthly multiplier for each month of the year
• Daily - A daily multiplier for each day of the week
• Hourly - Every hour, a multiplier for every hour from 12:00 to 23:00
• Weekend - Weekend hour multipliers for weekend days

Each dry weather Inflow (flow or quality) can have up to four patterns associated with it, one for each type listed above.

Monthly weather patterns can also be used to adjust the baseline values of the following hydrological parameters:

• Storage of subcatchment Depression
• Roughness of the subcatchment permeable surface
• Soil infiltration recovery rate

Time patterns have the following properties:

• Identification
  • Description - Use a friendly description when the item name is not enough
  • Name - name of the item
    Avoid names that are too long, or that contain the following characters: '*', '>', '<', '/', '\', '"', ':', ';', '|', '=', '`', '#', ',', '?'
  • Priority - Information about the current state of the item. It might be:
    • Neutral: no problem
    • Critical: Some issue that prevents the item from being calculated or used
• SWMM
  • Time Pattern Data - Time Pattern Data