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Rainplot Instructions - Analyze the Dataset
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Topics
- Select a dataset (choose
station and date range and retrieve from your "rainfall" database)
- Quality control the dataset
- Analyze the dataset (fit data to probability distributions
and generate IDF curves)
- Create reports (generate automated
reports of your analyses)
- Show summaries (show
mean monthly, mean annual, and other summaries statistics)
- Display data on map
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1. Click the 'Analyze Dataset' button on the main menu.
The following spreadsheet will open displaying the annual (or partial
series) maximum intensities (maxima) for given durations for the retrieved
dataset. All durations are given in hours, and all depths are given in
millimeters.
Right clicking inside the spreadsheet will allow you to change the displayed
content to these options: display volume, display intensity, display date,
display storm, or remove a selected row from the analysis.
2. Use the buttons on the top right part of the window to select the
method by which the maxima will be selected, depending on your analysis
or research objectives. Maxima will be selected by annual series, partial
series using a selected cutoff value, or partial series using a selected
number of points.
Annual Series: The highest intensity that occurs during each water
year for each displayed duration. Only one value per water year is selected.
Annual Series is the default method.
Partial Series Using Cutoffs: All intensities that are greater
than the user-defined lower limit threshold. As explained below, a lower
limit threshold is defined for each duration. Multiple values are possible
within a single year and within a single storm, and there is no limit
on the number of intensities that may be selected.
To set the cutoff threshold value for each duration, click the 'Select
Durations' button at the bottom of the window. The following dialogue
will open, allowing you to edit, add ('Add New Duration'), and
delete ('Delete Durations') durations and corresponding cutoff
threshold value. Click 'Save Durations' to save your changes.
Partial Series Using Number of Points: The n highest intensities
of the dataset. As explained below, the total number of intensities to
be selected is defined by the user. Multiple values are possible within
a single year and within a single storm, and the number of intensities
that are selected is equal to the user-defined n. The following dialogue
will open when you select 'Partial Series Using Number of Points'.
Enter the number of maxima values that you would like to be selected.
3. Using the buttons at the bottom of the window, choose the way that
the retrieved maximas will be displayed. You may viewed the maxima as
a standard duration view ('Duration View') or as a database view ('Database
View').
Also, the spreadsheet may be sorted on a particular column by clicking
on the column and then clicking the 'Sort on Column' button on
the right side of the window. The spreadsheet may be printed by clicking
the 'Print Spreadsheet' button. A printable report may be displayed
by clicking the 'Display Report' button.
4. After retrieving the selected maxima, you are now ready to perform
statistical analyses on the data. The objective is to create a predictive
mathematical representation of the data. Specifically, intensity predictions
are made for selected durations by fitting the data to various probability
distributions. If multiple durations are analyzed, an Intensity Duration
Frequency (IDF Curve) model may be developed. The IDF Curve is the most
widely used and accepted product of rainfall-intensity analyses and is
used by engineers and planners a predictive tool for design decisions.
Two types of analyses are possible: 'analyze column' (analyze maximum
intensities for a single duration) and 'analyze all' (generate an intensity-duration-frequency
curve by analyzing maximum intensities for all durations).
Analyze Column - - Analyze Maximum Intensities for a Single Duration
Click on a column that corresponds to the duration of interest, and then
click 'Analyze Column'. The maximum intensities for that duration
are displayed in a pop up spreadsheet (shown below) and are graphed using
the user-defined plotting position and user-defined statistical distribution.
The first step in analyzing the single duration is to select a distribution
(a mathematical representation) to which to fit the raw data. To do this
select a Statistical Distribution from the pull-down menu. The intensity
values automatically will be updated with the new predictions based on
the distribution selected. You may test the curve fit of various distribution
types to determine the best equation for the data. A number of statistical
distribution types are available.
The next step is to select a Plotting Position from the pull-down menu
for the predicted data. Once selected, the curve fit automatically will
be applied to the distribution results. A number of plotting positions
are available.
Various distribution types and plotting positions may be tested in order
to arrive at a "best fit", and various curve-fit statistics
are provided in the lower left corner of the window.
Analyze All - - Analyze Intensities for All Displayed Durations
('Analyze All')
Click the 'Analyze All' button. The predicted maximum intensities
for each duration and return period are displayed in the spreadsheet window.
The displayed values are predicted on the basis of the user-defined statistical
distribution type and the user-defined curve fit.
(View of left panel of spreadsheet window)
As shown below, the plot of these values is shown in the right panel
of the window. At the bottom of the plot window is a check box allowing
you to display theoretical points ('prediction only') or both actual and
theoretical points ('all data').
(View of right panel of spreadsheet window)
A number of statistical distribution types are available in the 'Select
Distribution' pull down list at the top of the window.
A number of plotting positions are available in the 'Select Curve Fit'
pull down list in the center of the window.
A number of return periods are available.
| Note: Data may be pasted to the RAINPLOT spreadsheet window
in order to analyze datasets that are not stored in your "rainfall"
database (for example, flood-frequency data and others). Similarly,
data may be cut from the RAINPLOT spreadsheets and pasted into other
applications. |
5. Click the 'Display IDF Curve' button to display a report-quality
intensity-duration-frequency curve for the dataset. The exact duration
and intensity values may be determined for any point on the curve by moving
the mouse pointer over the point; the corresponding values will be displayed
in the top area of the window.
Click the 'Display Report' button to view a printable report from
your web browser.
Click 'Done' to return to the main menu.
Proceed to the next section titled 'Create
Reports' or return to the main
RAINPLOT instructions page.
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![[Thumbnail map]](../../icons/smallmapofregion.gif){kind=icon}
Middle
East Rainfall Intensity