Delta Hydro Studio
Browser-based hydrology and hydraulics calculators for practising engineers — no install, report-ready output.
Free web tool for building synthetic design-storm patterns — 560+ temporal patterns, exportable to SWMM and HMS.
World Rainfall Pattern Painter generates synthetic rainfall hyetographs in the browser: set a depth, duration and time step, pick from a library of over 560 temporal patterns spanning 190+ countries (including Gulf-region DDF tables and IDF lookup helpers), compare candidate patterns side by side, and export in formats ready for EPA SWMM, HEC-HMS and InfoWorks ICM.
It is a lightweight, freely accessible utility rather than an institutional product — useful for quickly producing regionally-shaped design storms and for comparing how pattern choice moves results. As always, confirm the governing local standard before a pattern goes into a compliance submission.
Other urban stormwater & infrastructure tools covering similar workflow stages.
Browser-based hydrology and hydraulics calculators for practising engineers — no install, report-ready output.
The public-domain engine of urban drainage: dynamic-wave pipe networks, runoff, LID and water quality.
EPA's free tool for estimating site runoff reduction from green infrastructure, with climate scenarios.
EPA's toolbox for sanitary sewer overflow planning — RDII analysis with the SWMM engine underneath.
The US land-development standard for TR-55/TR-20 hydrographs and detention pond design.
Autodesk's integrated catchment model — the heavyweight for large sewer networks and coupled 2D flooding.