Time of travel (time of entry, time of concentration)

Time of travel (time of entry, time of concentration)

Generally these names refer to the time required for water to flow from the farthest point on a catchment to its outlet during a storm, following flow paths dictated by natural topography and human changes.

Times of flow are complex, since they depend on the intensity of rainfall as well as surface effects, and there is really no constant time. In DRAINS, separate times are required for paved, supplementary and grassed sub-areas using Horton (ILSAX) hydrology (and for impervious and pervious areas in the Rational Method, ERM and IL-CL models).

DRAINS provides various options to calculate travel times. Time of travel is also important for bypass flows or overflows from pits. At present, the time taken for them to reach their destination can be defined as a constant value in DRAINS, and you can allow DRAINS to calculate these.