Delta Hydro Studio
Browser-based hydrology and hydraulics calculators for practising engineers — no install, report-ready output.
Virginia DEQ's official Excel workbooks for stormwater compliance via the Runoff Reduction Method.
by Virginia DEQ
Virginia's Runoff Reduction Method spreadsheets are the state's official compliance calculators: land cover in, BMP treatment train selected, phosphorus load reduction and runoff-volume credits out, per the state stormwater regulations. New development and redevelopment workbooks cover the two regulatory pathways.
They earn a listing as the archetype of a whole genre — regulator-published Excel calculators that define compliance arithmetic in many US states and beyond. If you work under a different authority, the pattern (and the pitfalls of versioned regulatory spreadsheets) transfers directly: always confirm you are on the current workbook before submitting.
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.
Python interface to the SWMM engine — step through simulations, read state, and control gates in real time.
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.