Runoff

TR-55 Peak Discharge — graphical NRCS method online

Graphical peak discharge method following USDA NRCS TR-55 for estimating post-development flows and comparing pre/post scenarios.

What is TR-55 Peak Discharge Calculator?

Graphical peak discharge method following USDA NRCS TR-55 for estimating post-development flows and comparing pre/post scenarios.

When would you use this?

  • Site development studies that need a documented TR-55 style peak discharge.
  • Comparing pre- and post-development hydrology for stormwater submissions.

How Delta Hydro Studio handles it

  • Structured TR-55 workflow with clear inputs for curve numbers and time of concentration.
  • Complements other peak-flow methods available in the suite.

How to use it

  1. 1

    Launch the TR-55 calculator in the studio.

  2. 2

    Enter drainage area, runoff curve number, and rainfall distribution inputs.

  3. 3

    Provide time of concentration (or derive it using the Tc tool).

  4. 4

    Run the calculation and export the summary for your memo or report.

Methodology & references

Full equations, assumptions, and literature references appear inside the in-app methodology panels for this tool, aligned with South African guidance (SANRAL TRH, SANCOLD, DWS technical manuals) and international references (USDA NRCS, FHWA HDS) where applicable.

Outputs & exports

Export professional Word and Excel report packs, tabulated results, and GIS-friendly layers depending on the tool. Screenshots in marketing materials are refreshed as the UI evolves — the studio always reflects the latest layout.

Ready to run TR-55 Peak Discharge Calculator?

Free tier available — no credit card required to explore.

FAQ

Do I need a desktop GIS install to use TR-55 Peak Discharge Calculator? +
No. Delta Hydro Studio runs in the browser — upload inputs, run calculations, and export professional outputs without local GIS installs for most workflows.
Is there a free tier? +
You can start free on the Stream plan with credits to explore tools. Several hydraulic and delineation tools remain accessible without a paid subscription.
Where are my data and calculations stored? +
Projects live in your Delta Hydro Studio workspace. Export Word, Excel, and GIS formats when you need offline archives or submittals.

Related tools

Ship compliant studies faster

Create your workspace on the Stream plan, then open TR-55 Peak Discharge Calculator when you are ready to run production calculations.