QGIS ReFH2 to TUFLOW: Difference between revisions
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[[File:Plugin ReFH2 Menu.png|
Once the ‘Extract ReFH2 for TUFLOW’ tool has been selected, the ReFH2 to TUFLOW Dialog will appear.
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[[File:ReFH2 To TUFLOW Menu.png|
The tool has a number of data input sections with the following headings associated with them:-
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[[File:ReFH2 Location.png|
When using Catchment Descriptors, the area value from the XML file will be used. For Point Descriptors, there is no area value within the XML file, so the user is prompted to provide an area in km<sup>2</sup>. This can be user specified or can be taken from a GIS polygon specified in a later section. If specifying an urban area, also in km<sup>2</sup>, this is used with Catchment Descriptors for Urban Outputs only. For point descriptors, the urban area is used for both Rural and Urban outputs. The urban area represents the mapped urbanised area within the catchment
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[[File:ReFH2 Event Selection.png|
The user can also specify a duration and a timestep. If no duration is specified, then the ReFH2 to TUFLOW tool will use the recommended duration determined by the ReFH2 software. The recommended duration is a function of the time to peak parameter (Tp) and the catchment average annual rainfall (SAAR). Once the duration is specified, an appropriate timestep is required that meets the requirement that the duration must be an odd multiple of the timestep. Table 1 below shows some common timesteps for some common durations. Where possible it is recommended a timestep between 10% and 20% of the duration should be used.
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[[File:ReFH2 Input GIS.png|
===Output===
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As well as the option to specify Gross or Net rainfall, the user can also select the rainfall type. The options are rural and urban. The rural rainfall is the default option which would represent the situation were the subcatchment 100% rural whereas the urban rainfall allows the representation of the URBEXT2000 parameter or Urban Area if specified in the 'Location' section. Further control over the impact of urbanisation can be carried out within the ReFH2 software. Note, that this option will only affect the Net Design Rainfall, it will have no impact on the Gross Design Rainfall. The output in both cases is the Total net rain mm (ARI) which for the rural model is 100% rural and with the urban model is the sum of the Urban net rain mm (ARI) and the Rural net rain mm (ARI). When using point descriptors, it is important to specify an appropriate Urban Extent in the 'Location' section to derive the correct losses for the study area.
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[[File:ReFH2 Output.png|
The other option is to output an inflow hydrograph which can be output to TUFLOW 1D_bc, 2D_bc and 2d_sa boundaries. The user can again select the rural and urban boundary types. There is also the option to select the inflow, ReFH2 calculates the total runoff as the sum of direct runoff and base flow. The direct runoff is obtained via a soil moisture accounting approach to convert rainfall to direct runoff. The base flow model is based on the linear reservoir concept. Splitting up the runoff hydrographs allows the user to apply the direct runoff as a 2d_sa boundary to apply the flow over a region and then add the base flow as a point or line source elsewhere within the model domain. The ReFH2 to TUFLOW tool allows different combinations of hyetographs and hydrographs to be output (for example, Net Rural Rainfall hyetographs with Urban Direct Total Runoff Hydrographs).
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