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A link configured for lagged flow routing is treated as a series of sub-reaches or 'divisions' of equal length, with the travel time in each division equal to one time-step. Water moves through the link progressively, without attenuation. You cannot configure fluxes, constituents or ownership on a lagged flow routing link. If lateral flows are significant and/or there is dead storage in the reach, you can model lagged flow routing using storage routing and the generalised non-linear storage option, as follows:

1. Compute the number of divisions, n, by dividing the dividing average travel time (ie. wave passage time

1. ) by model time-step and round the result to a whole number. The result must be at least one (ie. n ≥ 1);
2. Configure a storage flow routing reach where:
   • n = number of divisions;
   • x = 1;
   • m = 1; and
   • k = model time-step.
3. If you need to account for lateral flows where n = 1 and the average travel time is a fraction of the model time-step (eg. a reach with a one day lag in a model with a monthly time-step), you can adjust k to

1. the smaller time step value without affecting the shape of the hydrograph.  For stability K ≤ dt/x and in this case x = 1.