Inflow to a catchment can be in the form of direct runon from another catchment or upstream stormwater subsystem. With the Explicit (SWMM) solver opt to have a link outflow onto a catchment via the 'Route to Catchment' option on an Outfall element. Alternatively, By simply declaring the Outflow Element of a catchment to be another catchment, overland flow can runon to a downstream catchment. However, this configuration is only possible amongst two catchments which each utilize the EPA-SWMM Runoff Method.