Design the drainage of a subdivision or road from rainfall to outlet. Pick or paste the IFD, lay out pits and sub-catchments, and the studio accumulates flows down the network by the rational method, checks every pipe's capacity, velocity and grade, runs the hydraulic grade line up from the tailwater with pit losses and sizes the pipes; culverts get inlet- and outlet-control headwater by FHWA HDS-5 against the road level, and detention basins are routed for a range of storm durations to hold the post-development peak below the pre-development flow — with plans, long sections, hydrographs, a 3D view, calculation sheets and Excel.
Scope & limitations
Preliminary drainage design for study and feasibility. The sample IFD tables are illustrative — use the Bureau of Meteorology design rainfall for the site and have the design checked by a qualified engineer.
What the Stormwater & Drainage Studio does
Rainfall comes from an IFD table: pick one of the illustrative samples or paste the Bureau of Meteorology design rainfall for the site; intensities are interpolated log-linearly in duration for the minor and major AEPs.
For a pit and pipe network, each pit carries its sub-catchment (area, impervious fraction, flow path and slope). Runoff coefficients follow ARR 1987 / QUDM (C10 with frequency factors), inlet times use Friend's overland flow equation, and flows accumulate down the network with travel times in the pipes. Every pipe is checked for full-bore capacity, velocity and grade, and the hydraulic grade line is run up from the outlet tailwater with friction and pit losses to check freeboard; one button sizes the pipes from the outlet upstream.
Culverts (box or pipe, any number of barrels) are checked for inlet control with the FHWA HDS-5 equations and outlet control with the energy equation, against the road level and freeboard, with the outlet velocity and a headwater–discharge curve.
Detention basins are routed by the level-pool method for a range of storm durations using modified rational hydrographs, comparing the peak outflow with the pre-development peak; the orifice can be sized automatically. Output: plans, long sections, hydrographs, IFD curves, a 3D view, PDF calculation sheets, A3 drawings and Excel.