Initial Accumulation of Pollutants

The Pollutant Initial Accumulation editor is invoked by clicking the properties of the SWMM Subcatchment.

It specifies the amount of pollutant buildup existing in the subcatchment at the start of the simulation.

The spreadsheet contains the following columns:

• Pollutant - The name of the pollutant
• Accumulation Rate - The initial amount of accumulation
  If no accumulation value is provided for a pollutant, it is assumed to be 0. Accumulation units are pounds per acre when US units are in use or kilograms per hectare when SI metric units are in use.

If a non-zero value is provided for the initial buildup of a pollutant, it will override any initial rollup calculated from the parameter Swmm / Dates / Dry Days