SWMM - Time Series

Time series objects are used to describe how certain object properties vary over time. Time series can be used to describe:

• Data from temperature
• Data from evaporation data
• Data from rain
• Water stage on outfall nodes
• Hydrographs of external inflow at drainage system nodes
• External input Polutographs at drainage system nodes
• Control Settings for pumps and flow regulators.

Each time series must be given a unique name and can be assigned any number of time value data pairs. Time can be specified as hours from the start of a simulation or as an absolute date and time of day. Time series data can be entered directly into the program or accessed from a user supplied time series file.

Note: For rainfall time series, it is only necessary to enter periods with non-zero rainfall amounts. SWMM interprets the precipitation value as a constant value that lasts for the specified recording interval for the rain gage using the time series. For all other types of time series, SWMM uses interpolation to estimate values at times that are between recorded values.

Note: For times outside the time series range, SWMM will use a value of 0 for the rainfall and external inflow time series and the first or last value in the series for temperature, evaporation, and stage water time series.

• 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
  • Start Date - Date when the simulation starts
  • Start Time - Time of day the simulation starts