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tkan

Direct Rainfall Modelling

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Hi,

I have seen Bill Syme summarise the application of IL and CL for direct rainfall modelling in a 2007 post (see below).  Does the new version of TUFLOW still apply the 2d_rf attributes prior to application of IL and CL values? If so does the use of a materials.csv overcome this (as presented in the tutorial module)?


Thanks

 

2007 Post - For the direct rainfall approach the 2nd and 3rd attributes of the 2d_rf layer (see Table 4.24) are for factoring the rainfall (both are applied before the IL and CL values assigned to the materials are applied). So you could factor up the rainfall in this way. Note, though if there is a significant amount of rainfall outside the active model area, you may need to apply a 2D QT or other flow boundary where the inflow is coming in. The direct rainfall approach is really only designed for rain falling directly onto 2D cells.

Note that the direct rainfall approach is presently still considered developmental. If your ground elevations are high (>100m) you may need to trial an undocumented feature that uses real*8 for calculating water levels (sometimes real*4 precision is not sufficient when adding rainfall to the water elevation). To try this, set "Double Precision == ON" in the .tcf file. You will also need very small wet/dry depths (the new defaults are 2 and 1mm, which should suffice, but we do have models with 0.2 and 0.1 mm).

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Hi Tkan,

The 2nd and 3rd 2d_rf attributes are applied prior to the Initial Loss (IL) and Continuing Loss (CL) values in the materials.csv. The 2d_rf attributes are primarily designed to enable the representation of spatial variation in rainfall intensity across a catchment, not changes in loss parameterisation.

For example, rainfall in the headwaters of a catchment may be more intense than the lower catchment, though still use the same design event temporal pattern. The 2nd and 3rd 2d_rf attributes allow the representation of this variation within the model.

Cheers,

Chris

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