Version 2 of the Rainfall Intensity software is now available! It corrects many of the "bugs" reported in the previous version.

Rainfall Intensity Home
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USER'S MANUAL

REQUIRED DATABASES

Create a "rainfall" database

Create a "rainfall_stats" database

Set each database as a System DSN to allow connection to the RAIN software

RAINSTART

Open the RAIN software

Log On to RAIN software programs

RAINDIGITIZER

Getting Started - Things to Do Before You Begin Digitizing

Log On

Link to your "rainfall" database

Digitize a strip chart and save as an x,y ascii file on your hard drive

QC the digitized strip charts

Load digitized ascii file(s) to your "rainfall" database

Convert digitized ascii file(s) to meaningful rainfall data (time-depth series) and store in your "rainfall" database

RAINPLOT

Select a dataset (select data to analyze)

Quality control the selected data (view raw rainfall data)

Analyze the selected data using predictive statistical curve fits (includes IDF analysis)

Create a report (automated reports showing various results)

Show monthly and seasonal summaries

Display data on map using RAINMAP

Edit hydrologic default settings (customize program settings such as "months that comprise a water year" and others)

RAINSHARE

Log On

Edit, add, or delete data in your "rainfall" database

Export or import your "rainfall" database

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Convert Digitized Ascii Files to Meaningful Rainfall (Time-Depth) Data

The last step in the digitizing process is to convert the digitized ascii file data (raw digitized x,y data) to time-depth series data. This is done using the 'Convert ASCII Data to Time-Depth Data' option as follows.

Click the 'Convert ASCII Data to Time-Depth Data' button on the main menu.

This will open a window that allows you to select the settings that you will use to convert the data.

Ensure that the settings for alpha, digitized and manual depth, minimal time lapse, and hours from GMT are appropriate for your needs. Specifically, you will select: a) whether or not to use an alpha correction factor (explained below), b) whether to prorate the data using the digitized depth or the manual (gage) depth, c) a value for the minimal time lapse between points, and d) the correction factor for Greenich Mean Time.

Correct for Skewed Plot Pen (Use Alpha Pen Skew)

Using an alpha pen skew correction factor is optional and may be used to help account for instrument drum tilt and associated strip chart skew when the program is converting from digitized x,y points to time-depth values. This step is referred to as defining alpha pen skew. Alpha is a value that represents the amount of error (skew) associated with an instrument's plot pen alignment. If the plot pen does not drop instananeously, and therefore vertically, during a siphon cycle, the resulting offset may skew the remaining data. If the amount of rainfall in a 24-hour period is large, several syphons (and potential plot skews) may occur on a single chart.

Based on the software code, only one representative alpha value is used in the equation to correct the time-depth values. An appropriate representative value of alpha should be selected on the basis of judgement and on the basis of alphas obtained from a number of other charts produced by this instrument. (The average value of all alphas produced by given instrument often is selected as the representative value to be used in the conversion process.)

To define the alpha pen skew correction factor, click 'Define ALPHA Pen Skew' in the 'Populate Database with Digitized Data' section of the main menu.

The following screen will appear. To evaluate historic alpha values, choose an instrument from the pull-down menu at the top of the screen. This will produce a window containing all historic alpha values that exist in the stored ascii files for the selected instrument.

To view the average of all alpha values, click the 'Show Average' button in the center of the window.

As shown above, a graphical display shows all alphas and their corresponding dates. To view a close up of selected alphas click and drag on the spreadsheet. Selecting four or more records will produce a display of a graph of alphas for those records. Note that only actual alphas (and not "selected alphas") are plotted and used in the "average" calculation.

After reviewing the historic record of alpha values, you may enter a representative alpha (referred to here as the 'selected alpha'). Enter a value for the selected alpha that will be written to all ascii files by typing in the text box labeled "Alpha to Use". Click 'Write Alpha to DB' to save the selected alpha value to all ascii files in the CHART_ASCII table for that instrument. The selected alpha value will now be available for use when converting the ascii files to time-depth data.

Change the Default Depth

The 'Default Depth for Computations' is set by selecting either 'Manual Depth' or 'Digitized Depth'. The depth selected will be used in the time-depth conversion calculation. If you change your mind after leaving this window you may change the 'Default Depth for Computations' by right clicking on the depth in the worksheet that will open and selecting 'Change Selected Depth to Use'. The 'Default Depth' is the depth that you consider to be most reliable and accurate.

Select a Minimal Time Lapse between Two Points

The minimal time lapse between two points is the smallest amount of time (in minutes) that may reasonably occur between two adjacent digitized points. This value is dependent upon the type of chart you are digitizing ("7-day" charts have a larger minimal time lapse than "1-day" charts). If two digitized points are closer together than this value, they will be joined and act as a single point in the computation. The default value is 0.0.

Set the Hours Reduced from Local Time to GMT

The 'Hours Reduced from Local Time to GMT' is the number of hours that the chart's start time is from GMT. The default time in the Middle East is 2 hours, depending on daylight savings time.

After each of these settings have been selected, click 'Continue' to open the conversion spreadsheet window. (There may be a delay in opening this window because the program must read all of the records from the database that are available for conversion.)

Next, select a station from the pull-down list at the top of the window. After the station is selected, all records for that station will be visible in the spreadsheet.

Some ascii files may be highlighted in red. These files contain data with a potential quality control issue. For example, a red highlight can indicate that the end time for the record spills over into the next record's start time. That is, the end date/time of the highlighted record will be greater than the start date/time of the next record. A highlighted file and the file that follows it should be converted and loaded with caution.

Before choosing the files that you wish to convert, select the conversion options in the top portion of the window that are most appropriate to your needs. Three options are available:

1. Show All Records for Instrument. After selecting an instrument, you have a choice of displaying ALL records (that is, all ascii files) contained in the Chart_Ascii table of the "rainfall" database. Simply click on the box titled 'Show All Records for Instrument' in the top right part of the window. Otherwise, only those files in the Chart_Ascii table that have not yet been converted to time-depth data and loaded into the Chart table will be displayed. Note: This feature will help you know which records in the Chart_Ascii table have already been converted and loaded into the Chart table. If records already exist in the Chart table and you attempt to reload these data, the newer records will overwrite the existing records.

2. Write to Log. You also have a choice as to whether to write the conversion results to a log file for display. Simply click on the box titled 'Write to Log' in the top right part of the window. The purpose of the log file is to view the conversion results as they are generated. The log file also shows whether Chart table records were overwritten during the conversion process (as in the case when, for example, a strip chart is redigitized, reloaded to the database, and subsequently reconverted and populated into the Chart table for a second time). Clicking this box will result in a log file being written for each record (ascii file) that is converted. Note that this will slow the conversion process.

If you attempt to convert records that have already been converted in the database, the old records will be deleted prior to the new records being populated, and the log file will show this.

3. Overwrite Existing Records without Prompting. You also have a choice as to whether or not to automatically overwrite existing records in the Chart table. Simply click on the box titled 'Overwrite Existing Records Without Prompting' in the top right part of the window. Checking this box will significantly increase the speed of the conversion process. Checking this box will result in the program overwriting, without further prompting, records that already exist in the database for the same time period and station. That is, if an ascii file already exists in your "rainfall" databasefor the same time period and station, it will be reconverted and overwritten automatically. If this box is not checked, you will be required to confirm for each record that already exists that you wish to overwrite it with the record currently in the spreadsheet.

In addition, the following options are available by right clicking on a specific record in the spreadsheet:

1. View Selected Record (raw format) - This will allow you to view the unconverted raw ascii file for this record.

2. Change Selected Depth to Use - This allows you to switch the Default Depth to use for the conversion calculation for a single record.

When you have selected the ascii files that you wish to convert, click 'Convert Ascii Files to Time-Depth Data and Populate Database' at the bottom of the screen. The program will automatically calculate time-depth values from the raw digitized points and save these data in the "rainfall" database's Chart table.

If the 'Write to Log' is checked you will be able to view a data log after the conversion is completed. The log file will allow you to see the results of the conversion calculations and may be used for quality-control purposes.

The log displays the converted start date/time, end date/time, and depth in mm for each digitized segment. Each of these records are stored in the Chart table and represent time-depth series data. Maximum rainfall intensities and rainfall summaries may be derived from the data in the Chart table.

Return to the main RAINDIGITIZER instructions page.