This video describes the modelling of swales within InfoWorks ICM and CS. A swale is essentially a ‘leaky’ conduit, in much the same way that a soakaway is a leaky manhole. The shape and dimensions of the conduit, are defined in the usual way. The loss rate from the conduit is calculated, by InfoWorks, by multiplying the wetted area by the defined infiltration loss coefficient.
Two differing infiltration loss rates can be specified, one above and one below a defined ‘base height’. Differing values could be used for example where the base of the swale is rock, but the sides are grassed.
The same principles apply whether the conduit is a closed pipe, or an open channel, although a swale is much more likely to be an open channel.
There is an option within the simulation parameters ‘inflow is lateral’ which means that all inflows are applied uniformly along the length of the conduit (as would happen if flows where entering from the sides of the swale) rather than all at a node at one end of the conduit. This will however have little impact on the overall results.