SWMM5 Infiltration Lab is an interactive explorer for how EPA SWMM5 models infiltration into soil. It lets you configure and run infiltration simulations using the three methods SWMM5 itself supports: Horton's Equation, Green-Ampt, and the Curve Number method, then compare how each one responds to the same soil and rainfall inputs.
The app is a full-stack TypeScript project: a React front end renders interactive charts of the infiltration and runoff response using Recharts, while an Express backend runs the actual infiltration calculations server-side so results stay consistent across sessions. Simulation setups can be saved to a PostgreSQL database through Drizzle ORM, so a configuration you build once can be revisited later rather than re-entered from scratch. Each infiltration method also links out to its own page of technical background, for anyone who wants the theory behind the numbers rather than just the chart.
Released under the MIT License (see LICENSE).