Note: The new features in SWMM 5.0.021, which really are the new features in SWMM 5.0.019, 5.0.020 and 5.0.021 because of the way in which it was released. The big structural changes were made to the subcatchment, node, groundwater, infiltration and evaporation routines so that there is better continuity between the rainfall that falls on the pervious area of a watershed, the BMP/LID’s of the subcatchment (unlimited per subcatchment), evaporation, infiltration and storage nodes/ponds/lakes. A watershed or subcatchment is now simulated in layers:
· Pervious and Impervious Area surface runoff,
· Shallow Water Aquifer for Infiltration,
· Surface ponds with evaporation and infiltration,
· BMP and LID coverage under the pervious area,
· Two layer Groundwater Aquifer for flow to canals and manholes.