Pipeline Infiltration

Infiltration-Inflow is the water that enters the system from the ground through defective pipes, pipe joints, connections, or perforated stormwater pipes.

The Explicit (SWMM), Implicit (Dynamic Wave), GVF-Convex, and GVF-Rational solvers support a user-defined infiltration flow (Flow /Additional Infiltration). Also see "Conduit-Infiltration/Inflow and Seepage" for details.

Seepage is the flow loss from the system; it is the seepage of the conduit (or channel) from its bottom and side walls into conduit's surrounding soil. Only the SWMM solver supports the conduit seepage loss calculation among the four solvers. User can specify a seepage loss rate and the solver calculates the seepage loss at each time step using the loss rate and conduit flow area (based on the length and wetted-perimeter).

To model infiltration along a pipeline, it is possible to specify infiltration as:

Pipe length
Pipe area
Pipe diameter-length
Count
Hydrograph
Pattern load

The first four types of infiltration are constant rates while the last two are time varying inflows.

Note: Infiltration loading will be ignored by the calculation engine if it is assigned to a conduit whose upstream element is a Pond Outlet Structure.

Conduit infiltration flow is injected as a piped or fixed flow at the upstream end of the conduit by the calculation engine. Therefore, when viewing flow results, you will see the entirety of the local infiltration flow accounted for already in the middle section, and not just the downstream-most end of the link.