One of the first actions when evaluating a design is to select a hydrologic modeling program that evaluates the runoff-storage relationship within a contributing watershed. Sometimes this selection is made quickly without significant consideration of the end goal, or whether model results are comparable between different hydrologic programs. In theory, modelers can employ various hydrologic modelling programs and receive similar outputs if a system is evaluated under the same input parameters.

To test this theory, a small comparative analysis was performed between common hydrologic modeling programs: HEC-HMS, PCSWMM, and Bentley PondPack. Each model analyzed the same watershed and utilized the same hydrologic input parameters. Similar output results, such as cumulative runoff volume, peak discharge, time-to-peak, etc. were evaluated. The results of this analysis may inform water resource engineers and planners regarding appropriate hydrologic modelling approaches for future projects.