No firm numbers can be given for the required amount of calibration and verification events, but six of each should provide a robust calibration and verification. Depths and velocities are also available as are summary statistics on surcharging, volumes, continuity and other quantity parameters. The Statistics Block may be used to separate hydrographs and pollutographs into storm events and then compute statistics on parameters such as volume, duration, intensity, interevent time, load, average concentration, and peak concentration. A hydraulic design routine in the Transport Block will resize conduits to pass peak flows. Either metric or U.S. customary units may be used.
Most output is tabular.
The latter includes options for dynamic plots of the hydraulic grade line produced by the Extran Block. The two user's manuals clearly explain almost all computational assumptions of the model, several of which have been mentioned in preceding paragraphs. The model performs best in urbanized areas with impervious drainage, although it has been widely used elsewhere. The biggest impediment to model usage is the user interface, with its lack of menus and graphical output. Application History SWMM has an impressive longevity.