Ground Infiltration
Flow in drainage systems frequently exceeds the sum of stormwater runoff and domestic and trade inflows. This residual flow is usually attributed to infiltration, which enters the system through cracks. Unlike runoff, which responds to a rainfall event in minutes, infiltration inflows have a much slower response. There are two main types of infiltration:
- Rainfall-induced infiltration results from soil water infiltrating directly into the network. This has an effect on flow within hours or days of the storm.
- A proportion of rainfall percolates deeper into the groundwater reservoir and in the weeks or months following the storm the groundwater level may be sufficiently high to cause groundwater infiltration.
In order to include infiltration in a simulation, one or more ground infiltration records must be created for the network. Each record is identified by a Ground Infiltration ID. The record defines the infiltration data that will be applied to one or more subcatchments. Ground infiltration records are created and edited in the Ground Infiltration Grid Window of the Subcatchments Grid. A particular ground infiltration record is associated with each subcatchment by specifying the Ground Infiltration ID in the Subcatchment Grid Window of the Subcatchments Grid. A Ground Infiltration definition can be associated with more than one subcatchment.
The Ground Infiltration object defines the fixed groundwater characteristics of the subcatchment.
To include a time-varying profile for groundwater infiltration, a Ground Infiltration Event must be created. This event describes the way in which groundwater infiltration will be modelled over a period of time.
For details of the infiltration model used in InfoWorks ICM see the Ground Infiltration Model topic.
