Storms can be generated using the '4) Create Storms' button. This will populate the Storms grid as well as calculate information relating to Areal Reduction Factors (ARFs), Initial Losses and Routing Increments.
By default, the Create Storms button will clear any existing storms in the list before creating the new storms. However, if you click the drop down arrow on the button you can add new storm to an existing storm list. This can be useful, if you would like to add combinations of Standard, Frequent and Rare Events.
The Storms grid at the bottom represents a row for each storm that will be modelled. It will include a row for each combination of AEP, classification (rare, intermediate, frequent or reference area) and duration (that is matched to a row in the Rainfall Depths table). Examples of the Storms grid for point and areal temporal patterns are shown below. If text is displayed in red, then a warning is available that can be viewed by hovering over the cell.
If multiple IFD locations are assigned to the subcatchments, they will be shown in a comma separated list in the IFD Location(s) column. The IFD Depth, Net Depth and Avg Intensity columns will also have commas separated list entries that correspond to the IFD locations.
When a row in the Storms grid is clicked, relevant reference rows in other tables (such as ARF, burst losses, IFD depths, temporal patterns etc) will be highlighted in yellow to aid in cross-referencing the source of the data.
The Storms grid can be exported to CSV, exported to TUFLOW compatible rainfall hyetographs files and other options via right click.
Areal Reduction Factors (ARFs) are automatically calculated and displayed / charted in the panel.
Areal Reduction Factors are automatically calculated. If text is displayed in red, then a warning is available that can be viewed by hovering over the cell.
Storm Burst Loss values (mm) are automatically calculated and displayed / charted in the panel. These values are based on the settings adopted.
Initial Loss Values are calculated based on the users settings
If the user selects the option to add any excess pre-burst to the first rainfall time step then pre-burst excess (where a pre-burst adjustment exceeded the initial loss) will be indicated by a negative value and shaded in blue. This rainfall depth will be added to the first time step in the rainfall hyetograph when it is injected into the model.
Recommendations for the routing increment for the rainfall runoff model for storms of varying durations are calculated in the Routing Increments table. The parameters (including target number of increments, min and max increment duration, min and max storm length) can be adjusted and used to recalculate the suggestions. The Routing Increment is also calculated to be a whole number factor of the temporal pattern timestep (TP Timestep).
The Routing Increment can also be adjusted in this form to override the recommendations.
Note: These values are only suggestions and may not be appropriate for all hydrologic models. Care should be taken in selection of these values and testing should be undertaken to ensure the hydrologic model performs well with the routing increment assigned. XP-RAFTS can be sensitive to the Routing Increment and sensitivity analysis is recommended to ensure a sufficiently low value is used to ensure the reliability of the results.
Once the storms have been generated, the hydrologic modelling run files for the preferred hydrologic model can be generated.