A model that mixed Horton (ILSAX) and WBNM hydrology, located at Bowral, NSW

The file for this example, Bowral Rural-Urban Example.drn, is 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.  

This example shows how DRAINS can apply two hydrological models in the same model. A small urban area is modelled using Horton (ILSAX) hydrology while the stream to which it drains is modelled using WBNM hydrology.  In the calculations both hydrological models are operated at the same time step.  The ERM and IL-CL models can also be paired with a storage routing model like RORB, RAFTS or WBNM.

Here the stream levels do not define a tailwater level for the pipe system, but this can be done by adding open channel sections into which the WBNM model flowrates can be directed.  Water levels can be calculated in these sections, defining a variable tailwater level for pipe systems.

• Related Articles

• Horton (ILSAX) hydrological model

  The Horton (ILSAX) loss and routing models were taken from the programs from which ILSAX was developed, particularly ILLUDAS and ILLUDAS-SA. All use a loss model involving depression storages and the Horton infiltration model for pervious areas, and ...

• Layout for WBNM type storage routing model

  A catchment is divided into sub-catchments that depend on junctions of streams and internal ridge lines. Nodes should be placed at the outlets of self-contained sub-catchments - those at the top of the catchment, with no streamflow from upper ...

• Horton (ILSAX) Hydrological Model property sheet

  This window enables you to enter, view or edit rainfall-runoff models. The data involved are: the name of the model (e.g. Manly Beach Model), depression storages (mm) for paved, supplementary and grassed areas, a soil type for the grassed or pervious ...

• Hydrological model dialog box

  From this window you can select the hydrological rainfall-runoff model to be used. The current default model selected for Designand Analysis runs is shown in the list box to the left. Clicking the Delete Default Model button deletes the highlighted ...

• ILSAX

  ILSAX is a public domain MS-DOS program developed from the South African ILLUDAS-SA program, which was itself a development of the American ILLUDAS program and the British Transport and Road Research Method (known as the TRRL or RRL model). It was ...