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Preparation of ten-daily rainfall and ET0 maps for crop forecasting
Crop forecasting based on water balance calculations is usually done in a ten-day timestep. A ten day period is called a “dekad”. However, should daily weather data of good spatial and temporal extend be available, the water balance can be run in AgrometShell on a daily basis.
In order to do crop forecasting the following weather data have to be gathered:
- Actual decadal rainfall data for the running season.
- Actual decadal ET0 data for the running season
- Normal rainfall data
- Normal ET0 data
These data form indicators in itself, even without using them directly in a water balance calculation. Some examples are given below:
A simple rainfall map for the current dekad
Start the “Database-Map” function. This example will display rainfall data for a specific dekad in 2002 for Bangladesh. |
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With the world map as default, some cluttered data are shown for Bangladesh |
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Using the zoom buttons an image for just Bangladesh is selected. With the Copy-to-clipboard button this image can be copied to the clipboard and pasted into a word processor. |
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Accumulated rainfall from the beginning of the season
Excel is needed to do the accumulation.
In this example the accumulated rainfall for the season 1991-1992 is calculated. The example is for Zimbabwe where the season starts around November. The current dekad is assumed to be the second dekad of March 1992. Start the “Database-Export” function. Start a new export format |
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A list containing Zimbabwean stations is selected. |
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All stations in the list are presented. Now add columns with the Add button. |
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Specify the meteorological parameter to export. In this example 3 columns are exported added at the same time. |
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The same is done for all dekads until the current one (Dekad 2 of March 1992). When ready press next |
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Select Export to Excel |
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All data are presented in Excel |
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The totals are added using Excel formulas. |
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An accumulated rainfall image
By applying interpolation to the total rainfall amounts calculated in the previous step, an image is created.
In Excel the totals file has to be reformatted to a CSV file. This CSV file should have the column order (1)longitude (2)latitude (3)value (4)station name |
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Using the Interpolate-Inverse Distance function, the CSV file can be interpolated to an image. |
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The result is an image. This gives a much more visual picture of the cumulative rainfall. |
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