v2 - Edit Storm

v2 new feature - Edit Storm

One of the options in the Storm command is to use a pre-defined curve known as a Mass Rainfall Distribution curve. These files are given the extension *.MRD and define the fraction of rainfall depth R(t)/ Rtot as a function of ratio of elapsed time over total storm duration. Typical examples are for the various Huff storm quartiles and the SCS hyetographs.

The Edit Storm tool lets you modify an existing MRD file or construct a new one.

The above display shows the storm-editing window. In this example the 3rd quartile Huff storm has been imported by using the [Open File] command button. Alternatively, if no file is imported, the initial distribution is a straight line. The array of values must start with zero and end with 1.0 and the intermediate values must increase monotonically. The steepness of an incremental line segment defines the intensity of the resultant storm so clearly a negative slope would imply a negative rainfall intensity.

The values can be edited in two ways – by graphical manipulation or numerically.

Graphical Edits: Position the mouse pointer on one of the vertical grid lines and either above or below the red line. Each mouse click causes the numerical value in the table to increase or decrease by 0.01. By holding down the Shift key while clicking the mouse key increases the numerical change to 0.1.

Numerical Edits: Click on any cell in the grid with the exception of the 0.0 and 1.0 values and type in the desired value.

Any change in either the graphical or tabular display is reflected in the other.

The command buttons at the top of the form have the following functions:

[Open File] Load an existing MRD file.

[Accept] Accept the editing that you have done so far. This enables the [Save As] button

[Save As] Lets you save the new MRD data as a file. The first two records in the file will contain a brief description and the total number of values including the 0 and 1 values. If you have modified an existing MRD file the description will be shown in the ‘Description’ label. You will be prompted to either accept the current description or change it.

[Plot] Causes the current MRD data to be displayed as a hyetograph of rainfall intensities.This shows only the ‘shape’ of the storm and not actual intensities.

[Tabulate] Displays a table of Mass Rain Intensity values for a total rainfall depth of 1 unit. The number of intensity values is one less than the number of points in the MRD distribution.

[Insert] Insert an additional element in front of the currently highlighted cell in the grid. The new point is given a value that is the mean of the values before and after it and the ‘Number of values’ is increased by one. If the first zero value is currently highlighted no action is taken. The graphical display is updated to show the change.

[Delete] Removes the currently selected cell in the grid and reduces the number of values by one. The graph is updated.

[Undo] Reverses the last use of either the [Insert] or [Delete] command button.