What's The Big Difference? - A Descriptive Analysis of Common Hydrologic Modeling Programs

Iain Gordon, EIT, Project Engineer, Timmons Group

Kelsey Redman, EIT, Project Engineer, Timmons Group

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.

Author Bio

Iain: Iain is a Project Engineer in the Stormwater Services Group. He focuses on drainage improvement projects, stormwater management design, and stream design. Iain also has experience performing hydraulic analysis for various projects. His contributions also include compiling numerous reports pertaining to existing and in-progress BMP inspections. Iain is proficient in a variety of engineering software such as CAD, GIS, and hydraulic modeling software.

Kelsey: Kelsey is a Project Engineer in the Stormwater Services Group. She focuses on urban drainage improvement projects and stormwater management design. Kelsey has performed multiple analyses to demonstrate proof of concept for implementation of proposed design alternatives using SWMM software. She also has experience compiling reports for drainage improvement and flood studies. Kelsey is proficient in other software, including Civil3D, HEC-RAS, ARC-GIS, HEC-HMS, and PondPack.