Major/Minor design for a street drainage system at Gymea, NSW, using the extended rational method
The ERM was developed to model detention basins using a method that was consistent with the rational method, since it is usually impossible to adjust an Horton (ILSAX) model to match rational method peak flows for a range of average recurrence intervals and storm durations. Flowrates calculated by Australian Rainfall and Runoff (1987) rational method procedure are routed using the same time-area procedure as the Horton (ILSAX) model. The operation of the model is almost exactly the same as that with Horton (ILSAX) hydrology. When Australian Rainfall and Runoff storm burst patterns are used, as shown below, this method produces higher peak flowrates than the rational method.
It can also run with 1987 rainfalls and synthetic rainfall patterns derived from intensity-frequency-duration relationships. Note that the 'total areas' ERM model cannot run with the 2019 data, only the 'separate areas' model.
The example Gymea Rational & ERM ARR 1987 Example - Lite.drn shows the procedure with the I-F-D-based relationship. To get an exact match it is necessary to use synthetic rainfall patterns different from the 1987 or 2019 Australian Rainfall and Runoff patterns, as shown below. The hydrological model 'Gymea ERM - Total Areas' must be selected.
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Major/Minor design for a street drainage system at Gymea, NSW, using the rational method
The files for this example are Gymea Rational & ERM ARR 1987 Example - Lite.drn and Gymea Rational & ERM ARR 2019 Example - Lite.drn, located in the folder C:\ProgramData\Drains among the Lite examples. If this folder is hidden, in File Explorer ...Major/minor design for a small street drainage system at Gymea, NSW, using an IL-CL model and Lite hydraulic calculations
The initial loss - continuing loss urban hydrological model recommended in ARR 2019 is applied in this model, along with the rainfall ensembles and median design procedure for ARR 2019. A DRAINS file for the example, named Gymea IL-CL Example - ...Major/ Minor design for a street drainage system at Gymea using the ILSAX hydrological model
The file for this example is Gymea ILSAX Example - Lite.drn, located in the folder C:\ProgramData\Drains among the Lite examples. If this folder is hidden, in File Explorer select the View tab and tick the Show Hidden Items box to make it visible. ...Major-minor methods
This name refers to design and checking procedures in urban stormwater drainage practice that use two levels of storm event. The minor event is used to determine the layout and size of pipes and other elements for convenience and safety. For street ...Gymea street drainage system run with selected individual storms
The file for this example is Gymea IL-Cl Model with Individual Storms.drn, located in the folder C:\ProgramData\Drains among the Lite examples. If this folder is hidden, in File Explorer select the View tab and tick the Show Hidden Items box to make ...