Worked examples
See it worked through
Four real runs on app.curvenumber.com, step by step, each ending in a published link you can open. They were chosen for the cases where a figure is hard to defend: soil the survey will not rate, a practice too small for what drains to it, a hydrograph that is not the usual one, and a site too small for the land cover map. Examples 1 and 2 also run every storm, from water quality to the 100-year, in one table.
The places are real. The clients, plans and geotechnical reports are fictional, and each run says so. Every run was made under the CurveNumber Examples account, and every runoff depth for the design storm was checked by hand with the TR-55 runoff equation.
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Example 1
Commercial redevelopment on urban fill
Ballston, Arlington County, Virginia
Unrated urban soil answered from a geotechnical report, a curve number override, and an underground vault that passes every storm.
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Example 2
Residential subdivision in the woods, with bioretention
Chatham County, North Carolina
Woods to half-acre lots, the time of concentration estimate, and a bioretention area too small for most storms.
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Example 3
Special rainfall and unit hydrograph cases
Georgetown, Delaware, and Hillsboro, Oregon
The Delmarva unit hydrograph against the standard one, wetlands, dual soil groups, NOAA Atlas 2 and the Type IA storm.
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Example 4
A small lot, the aerial photograph check and a quick check
Olney, Montgomery County, Maryland
A lot too small for the land cover map, surfaces read off an aerial photograph, and the small area rule.
Before the examples
Getting started: projects, sites and the steps
Every piece of work in CurveNumber lives in a project (a client job) and its sites (each drainage area you analyze). A site moves through four steps and the report, shown across the top of the screen.
- SiteDraw the site on the map, or paste or import it. CurveNumber reads the soil survey, land cover, elevation and NOAA rainfall for it.
- TodayThe ground as it is: land cover and soils with their curve numbers, and any practice already built.
- ProposedDraw what you plan to build as land use shapes, and the practices that treat its runoff.
- ResultsCompute, then Run all storms: runoff and peak for each storm, before and after, what each practice does, and a pass or fail.
- Report and shareA printable report for the reviewer, and a fixed published link.
Each step shows its state: saved, needs review, or not started. Nothing is charged until the first run that gives a result.
Prepared by
Before your first report, fill in the Prepared by block on the Account page: your name, title, firm and website. Every report and published link prints it, labeled “as entered by the account holder”. Your sign-in email never appears on a report.
