Rainfall Smoothing
Many rainfall definitions are based on tables of depth vs. time values. The depth at intermediate times is commonly determined by linear interpolation. However, this procedure produces "steps" in the intensity curve which may also be visible in the resulting runoff hydrographs, especially at small Tc values.
To produce a continuous (non-stepped) intensity curve, HydroCAD automatically applies a "smoothing" operation to all rainfalls that employ tabular depth values. This results in a slight delay in the depth curve. However, peak intensity and runoff are usually not effected, and the visible steps are eliminated.
 | If you prefer to have an exact match to the original depth values, you can
disable Rainfall Smoothing on the
Advanced tab of the Calculation
Settings screen. This option (added in HydroCAD
9.1) applies only to the current project. |
| For earlier versions of HydroCAD, you can add the statement "Smoothing=False" to the end of the applicable rainfall definition. Note that this will change the results for all projects that utilize this rainfall definition, so the previous option is generally preferred. (When making this change, you should add "Steps" to the end of the rainfall file name to distinguish it from the original file.) |